JP6831512B2 - Silver microsphere and its manufacturing method - Google Patents
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- JP6831512B2 JP6831512B2 JP2016215866A JP2016215866A JP6831512B2 JP 6831512 B2 JP6831512 B2 JP 6831512B2 JP 2016215866 A JP2016215866 A JP 2016215866A JP 2016215866 A JP2016215866 A JP 2016215866A JP 6831512 B2 JP6831512 B2 JP 6831512B2
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- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims description 167
- 229910052709 silver Inorganic materials 0.000 title claims description 163
- 239000004332 silver Substances 0.000 title claims description 163
- 239000004005 microsphere Substances 0.000 title claims description 90
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- FOIXSVOLVBLSDH-UHFFFAOYSA-N Silver ion Chemical compound [Ag+] FOIXSVOLVBLSDH-UHFFFAOYSA-N 0.000 claims description 51
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 claims description 41
- 229910052740 iodine Inorganic materials 0.000 claims description 41
- 239000011630 iodine Substances 0.000 claims description 41
- 238000003756 stirring Methods 0.000 claims description 36
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 28
- 239000007788 liquid Substances 0.000 claims description 20
- 239000011148 porous material Substances 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 8
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 229910045601 alloy Inorganic materials 0.000 claims description 5
- 239000000956 alloy Substances 0.000 claims description 5
- 239000006185 dispersion Substances 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 3
- 229910001316 Ag alloy Inorganic materials 0.000 claims 1
- 150000003378 silver Chemical class 0.000 description 14
- 239000002245 particle Substances 0.000 description 13
- 238000004416 surface enhanced Raman spectroscopy Methods 0.000 description 13
- 239000002994 raw material Substances 0.000 description 12
- 239000000243 solution Substances 0.000 description 12
- 239000000758 substrate Substances 0.000 description 12
- VYXSBFYARXAAKO-WTKGSRSZSA-N chembl402140 Chemical compound Cl.C1=2C=C(C)C(NCC)=CC=2OC2=C\C(=N/CC)C(C)=CC2=C1C1=CC=CC=C1C(=O)OCC VYXSBFYARXAAKO-WTKGSRSZSA-N 0.000 description 11
- 238000000479 surface-enhanced Raman spectrum Methods 0.000 description 10
- 230000004048 modification Effects 0.000 description 8
- 238000012986 modification Methods 0.000 description 8
- -1 silver-aluminum Chemical compound 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 229910000838 Al alloy Inorganic materials 0.000 description 6
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 238000009826 distribution Methods 0.000 description 6
- 238000001069 Raman spectroscopy Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000001878 scanning electron micrograph Methods 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical group II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 241000669298 Pseudaulacaspis pentagona Species 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000000349 field-emission scanning electron micrograph Methods 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 238000000879 optical micrograph Methods 0.000 description 3
- 238000004611 spectroscopical analysis Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000000026 X-ray photoelectron spectrum Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 239000012141 concentrate Substances 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000000731 high angular annular dark-field scanning transmission electron microscopy Methods 0.000 description 2
- 238000013507 mapping Methods 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 239000012299 nitrogen atmosphere Substances 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- 241000519995 Stachys sylvatica Species 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 239000005457 ice water Substances 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000001338 self-assembly Methods 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 238000002198 surface plasmon resonance spectroscopy Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
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Description
本発明は、表面増強ラマン基板や、汚染物質を電気吸着・濃縮する電極基板などに使用できる銀ミクロスフェアに関する。 The present invention relates to a silver microsphere that can be used for a surface-enhanced Raman substrate, an electrode substrate that electrically adsorbs and concentrates contaminants, and the like.
直径が数ｎｍから数十ｎｍの細孔を有する金属であるナノポーラス金属は、優れた電気伝導性、熱伝導性、および磁気特性、ならびに大きな活性表面積により、触媒反応、電気化学触媒反応、センサー、電子デバイス、および磁気記録媒体などへの応用が期待されている。ナノポーラス金属の一種であるナノポーラス銀は、金や白金のナノポーラス体と比べて低価格であるものの、銅やニッケルのような卑金属のナノポーラス体と比べると化学的に安定している。 Nanoporous metals, which are metals with pores of several nm to several tens of nm in diameter, have excellent electrical conductivity, thermal conductivity, and magnetic properties, as well as large active surface areas, which allow catalytic reactions, electrochemical catalytic reactions, sensors, etc. It is expected to be applied to electronic devices and magnetic recording media. Nanoporous silver, which is a type of nanoporous metal, is cheaper than the nanoporous bodies of gold and platinum, but is chemically stable compared to the nanoporous bodies of base metals such as copper and nickel.
銀ナノ粒子の凝集体から構成されるナノポーラス銀のスポンジ状構造体は、合金から不要な金属を選択的に溶かして銀を残す脱合金法によって得られることが知られている（非特許文献１および非特許文献２）。ナノポーラス銀は、高効率の触媒および表面増強ラマン散乱（ＳＥＲＳ）用のセンシング基板などに使用される。銀ナノ粒子の結合によって作製されたナノポーラス銀のスポンジ状構造体は、一般に強度が低く、外からの圧力や機械的な衝撃によって、または製造時の酸濃度や反応時間などによって、破壊されやすい。このため、このスポンジ状構造体は、使用時の耐久性と利便性に問題がある。 It is known that a nanoporous silver sponge-like structure composed of aggregates of silver nanoparticles can be obtained by a dealloying method in which unnecessary metals are selectively melted from an alloy to leave silver (Non-Patent Document 1). And non-patent document 2). Nanoporous silver is used in highly efficient catalysts and sensing substrates for surface-enhanced Raman scattering (SERS). Nanoporous silver sponge-like structures made by bonding silver nanoparticles are generally low in strength and are easily destroyed by external pressure, mechanical impact, acid concentration during production, reaction time, and the like. Therefore, this sponge-like structure has problems in durability and convenience during use.
本発明は上記事情に鑑みてなされたものであり、耐久性と利便性に優れた銀材料である銀ミクロスフェアを提供することを目的とする。 The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a silver microsphere, which is a silver material having excellent durability and convenience.
本発明の銀ミクロスフェアは、粒径１０〜２００ｎｍの銀ナノ粒子が結合されるとともに、開口径５〜５００ｎｍの細孔を備える構造を有し、直径が１０〜１０００μｍである。本発明のラマン分光測定用基板は、少なくとも表面が半導電性または導電性の基材と、基材の表面上に設けられた本発明の銀ミクロスフェアを有している。本発明の銀ミクロスフェアの製造方法は、粒径１０〜２００ｎｍの銀ナノ粒子が結合されるとともに、細孔を備える銀の凝集体を、液体と混合して、撹拌する工程を有している。 The silver microsphere of the present invention has a structure in which silver nanoparticles having a particle size of 10 to 200 nm are bonded and has pores having an opening diameter of 5 to 500 nm, and has a diameter of 10 to 1000 μm. The substrate for Raman spectroscopy of the present invention has at least a semi-conductive or conductive base material on the surface and the silver microsphere of the present invention provided on the surface of the base material. The method for producing silver microspheres of the present invention includes a step of bonding silver nanoparticles having a particle size of 10 to 200 nm and mixing silver aggregates having pores with a liquid and stirring the mixture. ..
本発明によれば、耐久性と利便性に優れた銀ミクロスフェアが得られる。また、電極に載せることによって、低濃度の計測対象物を吸着および濃縮できる銀ミクロスフェアが得られる。 According to the present invention, a silver microsphere with excellent durability and convenience can be obtained. Further, by placing it on an electrode, a silver microsphere capable of adsorbing and concentrating a low-concentration object to be measured can be obtained.
以下、本発明の銀ミクロスフェア、ラマン分光測定用基板、および銀ミクロスフェアの製造方法について、実施形態と実施例に基づいて説明する。重複説明は適宜省略する。なお、２つの数値の間に「〜」を記載して数値範囲を表す場合には、これら２つの数値も数値範囲に含まれるものとする。 Hereinafter, the silver microsphere, the substrate for Raman spectroscopic measurement, and the method for producing the silver microsphere of the present invention will be described based on embodiments and examples. Duplicate explanations will be omitted as appropriate. In addition, when "~" is described between two numerical values to represent a numerical range, these two numerical values are also included in the numerical range.
本発明の実施形態に係る銀ミクロスフェアは、粒径１０〜２００ｎｍの銀ナノ粒子が結合されるとともに、開口径５〜５００ｎｍの細孔を備える構造を有している。銀ナノ粒子の粒径および銀ミクロスフェアの細孔の開口径は、ＳＥＭ画像上で銀ナノ粒子および細孔を数個所計測したときの平均値である。本実施形態の銀ミクロスフェアは、直径が１０〜１０００μｍの球状粒子である。銀ミクロスフェアの直径も、ＳＥＭ画像上で数個所計測したときの平均値である。 The silver microsphere according to the embodiment of the present invention has a structure in which silver nanoparticles having a particle size of 10 to 200 nm are bound to each other and have pores having an opening diameter of 5 to 500 nm. The particle size of the silver nanoparticles and the opening diameter of the pores of the silver microspheres are average values when the silver nanoparticles and the pores are measured at several points on the SEM image. The silver microsphere of the present embodiment is spherical particles having a diameter of 10 to 1000 μm. The diameter of the silver microsphere is also an average value when measured at several points on the SEM image.
また、本実施形態の銀ミクロスフェアの空隙率は４０〜５０％である。銀ミクロスフェアの空隙率は、銀ミクロスフェアの外径と質量の計測値から見積もった。本実施形態の銀ミクロスフェアを構成する銀ナノ粒子の少なくとも一部は、表面がヨウ素で修飾されている。ヨウ素は、銀に対する化学親和性が強いことが知られている。ヨウ素は、銀の表面の誘電特性の調整、銀の導電性接点の改善、および銀のＳＥＲＳ感度の向上を確認するために利用されている。 The porosity of the silver microspheres of the present embodiment is 40 to 50%. The porosity of the silver microsphere was estimated from the measured values of the outer diameter and mass of the silver microsphere. The surface of at least a part of the silver nanoparticles constituting the silver microsphere of the present embodiment is modified with iodine. Iodine is known to have a strong chemical affinity for silver. Iodine has been used to adjust the dielectric properties of silver's surface, improve the conductive contacts of silver, and confirm the improvement of silver's SERS sensitivity.
本実施形態の銀ミクロスフェアは、ＳＥＲＳ検出の基板だけでなく、微量な汚染分子を電気的に濃縮する基板にも使用できる。すなわち、本発明の実施形態に係るラマン分光測定用基板は、少なくとも表面が半導電性または導電性の基材と、基材の表面上に設けられた本実施形態の銀ミクロスフェアとを有している。本実施形態のラマン分光測定用基板は、表面増強ラマン散乱効果を発現させることができる。 The silver microsphere of the present embodiment can be used not only as a substrate for SERS detection but also as a substrate for electrically concentrating a trace amount of contaminated molecules. That is, the Raman spectroscopic measurement substrate according to the embodiment of the present invention has at least a semi-conductive or conductive base material on the surface and a silver microsphere of the present embodiment provided on the surface of the base material. ing. The substrate for Raman spectroscopy of the present embodiment can exhibit a surface-enhanced Raman scattering effect.
本発明の実施形態に係る銀ミクロスフェアの製造方法は、粒径１０〜２００ｎｍの銀ナノ粒子が結合されるとともに、細孔を備える銀の凝集体（以下、銀ナノ粒子が結合されるとともに、細孔を備える銀の凝集体を「ナノポーラス銀」ということがある）を、液体と混合して、撹拌する工程を有している。本実施形態の銀ミクロスフェアの製造方法によれば、高性能で取り扱いやすい銀ミクロスフェアが簡易に得られる。ナノポーラス銀は、銀を含む合金の化学的脱合金法によって得られる。 In the method for producing silver microspheres according to the embodiment of the present invention, silver nanoparticles having a particle size of 10 to 200 nm are bonded, and silver aggregates having pores (hereinafter, silver nanoparticles are bonded and silver nanoparticles are bonded). It has a step of mixing silver aggregates having pores (sometimes referred to as "nanoporous silver") with a liquid and stirring them. According to the method for producing a silver microsphere of the present embodiment, a high-performance and easy-to-handle silver microsphere can be easily obtained. Nanoporous silver is obtained by chemical dealloying of silver-containing alloys.
ナノポーラス銀と混合する液体は、混合後の撹拌によってナノポーラス銀が分散する液であれば特に制限がない。このような液体として、メタノールやエタノールなどのアルコールが例示される。この液体は、ヨウ素を含んでいることが好ましい。ナノポーラス銀を構成する銀ナノ粒子の少なくとも一部の表面をヨウ素で修飾できるからである（以下、ナノポーラス銀を構成する銀ナノ粒子の少なくとも一部の表面をヨウ素で修飾したものを「ナノポーラス銀のヨウ素修飾体」ということがある）。ナノポーラス銀のヨウ素修飾体は、銀ナノ粒子部分の自己組織化によって強固に密着し、細孔を有する球状の集合体である本実施形態の銀ミクロスフェアになりやすい。ヨウ素を含んでいる液体としては、ヨウ素のアルコール溶液などのヨウ素の溶液が例示される。 The liquid to be mixed with the nanoporous silver is not particularly limited as long as it is a liquid in which the nanoporous silver is dispersed by stirring after mixing. Examples of such a liquid include alcohols such as methanol and ethanol. This liquid preferably contains iodine. This is because at least a part of the surface of silver nanoparticles constituting nanoporous silver can be modified with iodine (hereinafter, at least a part of the surface of silver nanoparticles constituting nanoporous silver is modified with iodine. It is sometimes called "iodine modifier"). The iodine-modified form of nanoporous silver adheres tightly due to the self-assembly of the silver nanoparticle portion, and tends to become the silver microsphere of the present embodiment, which is a spherical aggregate having pores. Examples of the liquid containing iodine include a solution of iodine such as an alcohol solution of iodine.
ヨウ素溶液を用いて銀ミクロスフェアを製造する場合、ナノポーラス銀は、予めこれを分散させた分散液を超音波処理した後に、ヨウ素溶液と混合することが好ましい。ナノポーラス銀をさらに微粒子化することで、ヨウ素による反応が十分に進行するとともに、粒子間の衝突も十分に行われ、ミクロスフェアのような集合体を形成しやすいからである。ナノポーラス銀の分散媒は、混合するヨウ素溶液の溶媒と同じであることが好ましい。溶解したヨウ素でナノポーラス銀を効率よく処理できるからである。ナノポーラス銀と液体の混合物は、２時間以上撹拌することが好ましい。銀ミクロスフェアの生成率を上げられるからである。ナノポーラス銀と液体の混合物は、２４時間以上撹拌することがより好ましい。銀ミクロスフェアの生成率が極めて高くなるからである。 When silver microspheres are produced using an iodine solution, it is preferable that the nanoporous silver is mixed with the iodine solution after the dispersion liquid in which the silver microsphere is dispersed is sonicated in advance. This is because by further micronizing the nanoporous silver, the reaction with iodine proceeds sufficiently, and collisions between the particles are sufficiently performed, so that an aggregate such as a microsphere is easily formed. The dispersion medium of nanoporous silver is preferably the same as the solvent of the iodine solution to be mixed. This is because nanoporous silver can be efficiently processed with dissolved iodine. The mixture of nanoporous silver and liquid is preferably stirred for at least 2 hours. This is because the production rate of silver microspheres can be increased. The mixture of nanoporous silver and liquid is more preferably stirred for 24 hours or longer. This is because the production rate of silver microspheres is extremely high.
本実施形態の銀ミクロスフェアの製造方法の具体的手順を以下に示す。まず、高純度の銀粉およびアルミニウム粉を、所定の物質量比（いわゆるｍｏｌ比）で混合する。つぎに、この混合粉を板状に加圧成形する。そして、この板状混合物を焼成・アニールした後、急冷する。こうして、ナノポーラス銀の原料である銀−アルミニウム合金が得られる。つぎに、気体が発生しなくなるまでこの銀−アルミニウム合金を酸に浸し（脱合金法）、その後、洗浄と乾燥を行ってナノポーラス銀から構成されるスポンジ状構造体が得られる。 The specific procedure of the method for producing the silver microsphere of the present embodiment is shown below. First, high-purity silver powder and aluminum powder are mixed at a predetermined substance amount ratio (so-called mol ratio). Next, this mixed powder is pressure-molded into a plate shape. Then, this plate-shaped mixture is fired and annealed, and then rapidly cooled. In this way, a silver-aluminum alloy, which is a raw material for nanoporous silver, is obtained. Next, the silver-aluminum alloy is immersed in an acid (dealloying method) until no gas is generated, and then washed and dried to obtain a sponge-like structure composed of nanoporous silver.
そして、このスポンジ状構造体を崩して得られた様々な大きさのナノポーラス銀を液体（例えばエタノール）に分散させる。つぎに、得られたナノポーラス銀の分散液を超音波処理する。さらに、この分散液を撹拌しながら、ヨウ素を含む液体（例えばヨウ素のエタノール溶液）を滴下する。そして、滴下終了後もしばらく撹拌を続ける。２時間以上撹拌することが好ましく、２４時間以上撹拌することがより好ましい。銀ミクロスフェアの収率が高くなるからである。 Then, nanoporous silver of various sizes obtained by breaking this sponge-like structure is dispersed in a liquid (for example, ethanol). Next, the obtained dispersion of nanoporous silver is ultrasonically treated. Further, while stirring the dispersion, a liquid containing iodine (for example, an ethanol solution of iodine) is added dropwise. Then, stirring is continued for a while even after the dropping is completed. Stirring for 2 hours or more is preferable, and stirring for 24 hours or more is more preferable. This is because the yield of silver microspheres is high.
最後に、遠心分離し、乾燥して銀ミクロスフェアが得られる。なお、ナノポーラス銀を構成する銀ナノ粒子の表面をヨウ素で修飾しない場合には、ヨウ素を含む液体の滴下工程を省略すればよい。銀ミクロスフェアの製造過程で、銀と脱合金法で溶かす金属の混合比、原料のナノポーラス銀と液体の混合比、ヨウ素の添加量、撹拌時間などを適宜調整することによって、粒径１０〜２００ｎｍの銀ナノ粒子が結合され、開口径５〜５００ｎｍの細孔を備え、直径が１０〜１０００μｍである本実施形態の銀ミクロスフェアが得られる。 Finally, centrifuge and dry to give silver microspheres. When the surface of the silver nanoparticles constituting the nanoporous silver is not modified with iodine, the step of dropping the liquid containing iodine may be omitted. In the manufacturing process of silver microspheres, the particle size is 10 to 200 nm by appropriately adjusting the mixing ratio of silver and the metal to be melted by the dealloying method, the mixing ratio of the raw material nanoporous silver and the liquid, the amount of iodine added, the stirring time, etc. The silver microspheres of the present embodiment are obtained by combining the silver nanoparticles of the present embodiment with pores having an opening diameter of 5 to 500 nm and a diameter of 10 to 1000 μm.
（銀−アルミニウム合金の製造）
純度９９.９９％の銀粉と、純度９９.９９％のアルミニウム粉を、１：４の物質量比で混合した。この混合粉を直径１ｃｍの円板状容器に入れ、６０ＭＰａで油圧プレスした。窒素雰囲気で、得られた成形体を６００℃で２時間焼結した。窒素雰囲気で、この焼結体を５４６℃で１２時間アニールした。その後、氷水で約３℃に急冷して、銀−アルミニウム合金を得た。
(Manufacturing of silver-aluminum alloy)
Silver powder having a purity of 99.99% and aluminum powder having a purity of 99.99% were mixed in a substance amount ratio of 1: 4. This mixed powder was placed in a disk-shaped container having a diameter of 1 cm and hydraulically pressed at 60 MPa. The obtained molded product was sintered at 600 ° C. for 2 hours in a nitrogen atmosphere. The sintered body was annealed at 546 ° C. for 12 hours in a nitrogen atmosphere. Then, it was rapidly cooled to about 3 ° C. with ice water to obtain a silver-aluminum alloy.
図１は、各種試料のＸ線回折パターンであり、（ａ）は成形体、（ｂ）は焼結体、（ｃ）はアニール後の合金をそれぞれ示している。なお、○はＡｇ、△はＡｌ／α−Ａｌ（Ａｇ）、◇はＡｇ2Ａｌ、◆はＡｇＡｌ3にそれぞれ起因するピークである。図１（ａ）から図１（ｃ）に示すように、この合金製造工程により、結晶相は、α−Ａｌ（Ａｇ）と様々な金属間化合物（Ａｇ2Ａｌ２Ｈ、Ａｇ3Ａｌ２０Ｃ、ＡｌＡｇ3２０Ｐ）の混合物から、純度約１００％のα−Ａｌ（Ａｇ）型の固溶体相に変化した。 1A and 1B show X-ray diffraction patterns of various samples, in which FIG. 1A shows a molded product, FIG. 1B shows a sintered body, and FIG. 1C shows an alloy after annealing. In addition, ◯ is the peak caused by Ag, Δ is the peak caused by Al / α-Al (Ag), ◇ is the peak caused by Ag 2 Al, and ◆ is the peak caused by Ag Al 3 . As shown in FIGS. 1 (a) to 1 (c), due to this alloy manufacturing process, the crystal phase is α-Al (Ag) and various intermetallic compounds (Ag 2 Al2H, Ag 3 Al20C, AlAg 3 20P). ) Was changed to an α-Al (Ag) type solid solution phase having a purity of about 100%.
（銀−アルミニウム合金の脱合金）
上記工程で得た銀−アルミニウム合金を、５％塩酸に３０分間浸漬して、アルミニウムを選択的に溶かして脱合金化し、さらに、気体が発生しなくなるまで１％塩酸に浸漬し、その後水で数回洗浄して、銀色光沢のナノポーラス銀のスポンジ状構造体を得た。このスポンジ状構造体は、ピンセットで刺したり、超音波で処理したりすることによって、様々な大きさの粒子となる。
(Dealloying of silver-aluminum alloy)
The silver-aluminum alloy obtained in the above step is immersed in 5% hydrochloric acid for 30 minutes to selectively dissolve aluminum to dealloy it, and further immersed in 1% hydrochloric acid until no gas is generated, and then with water. After washing several times, a silver-gloss nanoporous silver sponge-like structure was obtained. This sponge-like structure becomes particles of various sizes by being stabbed with tweezers or treated with ultrasonic waves.
図２は、各種試料のＳＥＭ画像または光学顕微鏡画像であり、（ａ）から（ｃ）はナノポーラス銀のＳＥＭ画像である。図２（ａ）から図２（ｃ）に示すように、このナノポーラス銀は、銀ナノ粒子が集まった線状の集合体が、さらに鎖状につながった構造を有している。図３は、ナノポーラス銀を構成する銀ナノ粒子の筋状体の大きさ、または銀ミクロスフェアを構成する銀ナノ粒子の筋状体の大きさを示すヒストグラムで、（ａ）は銀ナノ粒子の筋状体の全体的な大きさの分布を示している。図３（ａ）に示すように、図２（ａ）から図２（ｃ）のナノポーラス銀の筋状体の大きさは、７５〜８０ｎｍであった。 2A and 2B are SEM images or optical microscope images of various samples, and FIGS. 2A to 2C are SEM images of nanoporous silver. As shown in FIGS. 2 (a) to 2 (c), this nanoporous silver has a structure in which linear aggregates in which silver nanoparticles are gathered are further connected in a chain shape. FIG. 3 is a histogram showing the size of the streaks of silver nanoparticles constituting nanoporous silver, or the size of streaks of silver nanoparticles constituting silver microspheres, and FIG. 3A is a histogram of silver nanoparticles. It shows the distribution of the overall size of the streaks. As shown in FIG. 3 (a), the size of the streaks of nanoporous silver in FIGS. 2 (a) to 2 (c) was 75 to 80 nm.
（銀ミクロスフェアの製造）
以下の手順によって、ナノポーラス銀から４種類の銀ミクロスフェアを製造した。まず、ビーカー内で、約５０〜１００ｍｇのナノポーラス銀の破片と、５〜１０ｍＬのエタノールを混合し、２分間超音波処理した。つぎに、０.１ｍＭのヨウ素のエタノール溶液を撹拌しながら、１５分間以上かけて、このビーカー内に約８〜１６ｍＬ滴下した。そして、ビーカー内を２時間、６時間、１２時間、２４時間磁気撹拌した。つぎに、ビーカー内の分散液を遠心分離し、得られた固形分を６０℃で２時間真空乾燥して、銀ミクロスフェアを得た。
(Manufacturing of silver microsphere)
Four kinds of silver microspheres were produced from nanoporous silver by the following procedure. First, in a beaker, about 50 to 100 mg of nanoporous silver fragments and 5 to 10 mL of ethanol were mixed and sonicated for 2 minutes. Next, about 8 to 16 mL was added dropwise to the beaker over 15 minutes or more with stirring an ethanol solution of 0.1 mM iodine. Then, the inside of the beaker was magnetically stirred for 2 hours, 6 hours, 12 hours, and 24 hours. Next, the dispersion in the beaker was centrifuged, and the obtained solid content was vacuum dried at 60 ° C. for 2 hours to obtain silver microspheres.
なお、用いたナノポーラス銀の破片の質量、用いたエタノールの質量、滴下したヨウ素のエタノール溶液の体積、およびビーカー内の撹拌時間は、それぞれ次のとおりである。撹拌時間２４時間では、高収率で銀ミクロスフェアが生成した。また、撹拌時間２時間、６時間、および１２時間でも銀ミクロスフェアが生成するものの、その割合は高くなかった。
１００.８ｍｇ、 ６.１０８７ｇ、 １５.６７ｍＬ、 ２時間
４９.３ｍｇ、 ６.１６１６ｇ、 ７.８８ｍＬ、 ６時間
５０.０ｍｇ、 ６.１６００ｇ、 ７.８８ｍＬ、 １２時間
５０.０ｍｇ、 ６.１４９５ｇ、 ７.８８ｍＬ、 ２４時間
The mass of the nanoporous silver fragments used, the mass of ethanol used, the volume of the added ethanol solution of iodine, and the stirring time in the beaker are as follows. At a stirring time of 24 hours, silver microspheres were produced in high yield. In addition, although silver microspheres were formed even when the stirring time was 2, 6, and 12 hours, the proportion was not high.
100.8 mg, 6.1087 g, 15.67 mL, 2 hours 49.3 mg, 6.1616 g, 7.88 mL, 6 hours 50.0 mg, 6.1600 g, 7.88 mL, 12 hours 50.0 mg, 6.1495 g, 7.88 mL, 24 hours
図２（ｄ）から図２（ｇ）は、撹拌時間２４時間で得られた銀ミクロスフェアのＦＥ−ＳＥＭ画像を示している。また、図２（ｈ）は、両面導電性炭素テープを介して、銀ミクロスフェアをＦＴＯ電極上に接着したときの光学顕微鏡画像である。また、図３（ｂ）は、撹拌時間２時間で得られた銀ナノ粒子の筋状体の全体的な大きさの分布を示している。図３（ｃ）は、撹拌時間２４時間で得られた銀ミクロスフェアを構成する銀ナノ粒子の筋状体の大きさの分布を示している。なお、図３（ｃ）の柱のうち、前面のドット状柱は銀ナノ粒子の筋状体の隙間が多い部分の筋状体の大きさの分布を、背面の黒色柱と前面の柱に挟まれた中間の柱は銀ナノ粒子の筋状体が密集している部分の筋状体の大きさの分布を、背面の黒色柱は、前面と中間の柱を合わせた銀ナノ粒子の筋状体の全体的な大きさの分布をそれぞれ示している。 2 (d) to 2 (g) show FE-SEM images of silver microspheres obtained with a stirring time of 24 hours. Further, FIG. 2 (h) is an optical microscope image when the silver microsphere is adhered onto the FTO electrode via the double-sided conductive carbon tape. In addition, FIG. 3B shows the distribution of the overall size of the streaks of silver nanoparticles obtained with a stirring time of 2 hours. FIG. 3C shows the size distribution of the streaks of silver nanoparticles constituting the silver microspheres obtained with a stirring time of 24 hours. Of the pillars in FIG. 3 (c), the dot-shaped pillars on the front side have the distribution of the size of the streaky bodies in the portion where there are many gaps between the streaky bodies of silver nanoparticles, and the black pillars on the back side and the pillars on the front side. The intervening pillars are the distribution of the size of the streaks in the part where the streaks of silver nanoparticles are dense, and the black pillars on the back are the streaks of silver nanoparticles that combine the front and middle pillars. The distribution of the overall size of the shape is shown.
また、図４は、ヨウ素のエタノール溶液中で、ナノポーラス銀を各種時間撹拌して得られた試料のＦＥ−ＳＥＭ画像である。なお、図４（ａ）、図４（ｃ）、図４（ｅ）、および図４（ｆ）の白色の目盛棒は３０μｍを表しており、図４（ｂ）、図４（ｄ）、および図４（ｈ）の白色の目盛棒は１μｍを表しており、図４（ｇ）の白色の目盛棒は５００μｍを表している。 Further, FIG. 4 is an FE-SEM image of a sample obtained by stirring nanoporous silver for various times in an ethanol solution of iodine. The white scale bar of FIGS. 4 (a), 4 (c), 4 (e), and 4 (f) represents 30 μm, and FIGS. 4 (b), 4 (d), and FIG. And the white scale bar of FIG. 4 (h) represents 1 μm, and the white scale bar of FIG. 4 (g) represents 500 μm.
図２（ｄ）から図２（ｈ）および図４に示すように、この撹拌によって、銀ナノ粒子のヨウ素修飾体を含むマイクロサイズの粒子が、ヨウ素のエタノール溶液中で浮いている状態になり、これらの粒子が徐々に集まって、直径が数百μｍの銀ミクロスフェアになることがわかった。この銀ミクロスフェアは、原料の銀ナノ粒子の凝集体と比べて銀ナノ粒子が密集していた。また、この銀ミクロスフェアは、ピンセットでつまんで電極基板に接着したり、電極基板からはがしたりするのに十分な強度があった。この銀ミクロスフェアは、開口径が数十〜２００ｎｍの細孔を備え、空隙率が４０〜５０％であった。 As shown in FIGS. 2 (d) to 2 (h) and FIG. 4, this stirring causes micro-sized particles containing an iodine-modified form of silver nanoparticles to float in an ethanol solution of iodine. It was found that these particles gradually gathered to form a silver microsphere with a diameter of several hundred μm. In this silver microsphere, silver nanoparticles were denser than the aggregate of silver nanoparticles as a raw material. In addition, this silver microsphere was strong enough to be pinched with tweezers and adhered to or peeled off from the electrode substrate. This silver microsphere had pores with an opening diameter of several tens to 200 nm and a porosity of 40 to 50%.
磁気撹拌によるナノポーラス銀の粒子間の機械的衝突は、粒子間の捻じれ合いや絡み合いを生じさせやすくする。これが、銀ミクロスフェアの形成に重要な役割を果たしていると考えられる。また、銀ナノ粒子をヨウ素で表面修飾することによって、銀ナノ粒子同士の密集が促進できた。また、ナノポーラス銀をヨウ素で処理すると、分離した多数の銀ナノ粒子がナノポーラス銀の表面に析出した（図２（ｆ）および図２（ｇ）参照）。図２（ｆ）および図２（ｇ）では、ナノポーラス銀が白いスポットとして現れている。 Mechanical collisions between particles of nanoporous silver due to magnetic agitation tend to cause twisting and entanglement between the particles. This is considered to play an important role in the formation of silver microspheres. Further, by surface-modifying the silver nanoparticles with iodine, the density of the silver nanoparticles could be promoted. Further, when the nanoporous silver was treated with iodine, a large number of separated silver nanoparticles were precipitated on the surface of the nanoporous silver (see FIGS. 2 (f) and 2 (g)). In FIGS. 2 (f) and 2 (g), nanoporous silver appears as white spots.
図５（ａ）および図５（ｂ）は、撹拌時間２時間で得られた銀ナノ粒子の凝集体の画像である。すなわち、撹拌時間２時間で得られた生成物のうち、銀ミクロスフェア部分以外の銀ナノ粒子の凝集体の画像である。図５（ａ）は、ＨＡＡＤＦ−ＳＴＥＭ画像である。図５（ｂ）は、図５（ａ）の画像にヨウ素と銀の元素マッピングを施した画像である。図５（ｃ）は、銀ミクロスフェアの原料であるナノポーラス銀、撹拌時間２時間で得られた銀ナノ粒子の凝集体、および撹拌時間２４時間で得られた銀ミクロスフェアの銀の３ｄＸＰＳおよびヨウ素の３ｄＸＰＳスペクトルである。図５（ｂ）では、主に小さな銀ナノ粒子の表面にヨウ素が観測された。 5 (a) and 5 (b) are images of aggregates of silver nanoparticles obtained with a stirring time of 2 hours. That is, it is an image of an aggregate of silver nanoparticles other than the silver microsphere portion among the products obtained with a stirring time of 2 hours. FIG. 5A is a HAADF-STEM image. FIG. 5B is an image obtained by subjecting the image of FIG. 5A to elemental mapping of iodine and silver. FIG. 5 (c) shows 3dXPS and iodine of nanoporous silver, which is a raw material of silver microspheres, agglomerates of silver nanoparticles obtained with a stirring time of 2 hours, and silver of silver microspheres obtained with a stirring time of 24 hours. 3d XPS spectrum of. In FIG. 5 (b), iodine was mainly observed on the surface of small silver nanoparticles.
図５（ｃ）に示すように、銀の３ｄＸＰＳピーク位置が３６８.１ｅＶと３７４.１ｅＶであること、および図１（ｅ）と図１（ｆ）に示すＸＲＤの結果から、ナノポーラス銀の主な構造は、ゼロ価銀の面心立方構造であることがわかった。また、図５（ｃ）に示すように、撹拌時間２４時間で得られた銀ミクロスフェアを構成するナノポーラス銀には、ヨウ素が含まれていた。なお、撹拌時間２４時間で得られた銀ミクロスフェアのヨウ素ピークの位置がわずかに低結合エネルギー側にシフトしており、ヨウ素化された銀の増量を示唆している。 As shown in FIG. 5 (c), the 3dXPS peak positions of silver are 368.1 eV and 374.1 eV, and the XRD results shown in FIGS. 1 (e) and 1 (f) show that the main nanoporous silver. The structure was found to be a face-centered cubic structure of zero-valent silver. Further, as shown in FIG. 5 (c), iodine was contained in the nanoporous silver constituting the silver microsphere obtained with a stirring time of 24 hours. The position of the iodine peak of the silver microsphere obtained with a stirring time of 24 hours was slightly shifted to the low binding energy side, suggesting an increase in the amount of iodinated silver.
図３（ｃ）に示すように、ヨウ素修飾された銀ミクロスフェアの密集部分のナノポーラス銀の筋状体の大きさは、ヨウ素修飾された銀ミクロスフェアの隙間が多い部分のナノポーラス銀の筋状体の大きさと比べて、小さい領域に多く分布している。このため、銀ミクロスフェアを構成するナノポーラス銀の筋状体の平均的な大きさは、原料のナノポーラス銀の筋状体の平均的な大きさより小さい。銀ミクロスフェアの原料のナノポーラス銀とヨウ素の反応によって、ナノポーラス銀を構成する銀ナノ粒子の表面が擦れて、分離した銀ナノ粒子が形成され、そして、この分離した銀ナノ粒子が、銀ミクロスフェアを構成する筋状の銀ナノ粒子の表面上に付着したと考えられる。 As shown in FIG. 3 (c), the size of the nanoporous silver streaks in the dense portion of the iodine-modified silver microspheres is the nanoporous silver streaks in the gaps of the iodine-modified silver microspheres. It is widely distributed in small areas compared to the size of the body. Therefore, the average size of the nanoporous silver streaks constituting the silver microsphere is smaller than the average size of the raw material nanoporous silver streaks. The reaction between nanoporous silver, which is the raw material of silver microspheres, and iodine rubs the surface of the silver nanoparticles that make up nanoporous silver to form separated silver nanoparticles, and these separated silver nanoparticles are used as silver microspheres. It is considered that it adhered to the surface of the streaky silver nanoparticles constituting the.
ナノポーラス銀の局在表面プラズモン共鳴（ＬＳＰＲ）の特性は、紫外可視吸収スペクトルで表わせる。図６は、銀ミクロスフェアの原料の銀粉（Ａｇ ｐｒｅｃｕｒｓｏｒ）、銀ミクロスフェアの原料のナノポーラス銀（０ｈ）、撹拌時間２時間、６時間、および１２時間で得られた銀ミクロスフェアの生成途中の銀ナノ粒子の凝集体（２ｈ、６ｈ、１２ｈ）、ならびに撹拌時間２４時間で得られた銀ミクロスフェア（２４ｈ）の紫外可視拡散反射分光スペクトルである。銀粉と銀ミクロスフェアの原料のナノポーラス銀は、ヨウ素修飾前の銀である。撹拌時間２〜２４時間で得られた銀ナノ粒子の凝集体または銀ミクロスフェアは、ヨウ素修飾後の銀である。図６に示すように、ヨウ素修飾前後の全ての銀が、銀のプラズマ端に対応する波長３１７ｎｍの光の吸収を示した。 The characteristics of the localized surface plasmon resonance (LSPR) of nanoporous silver can be represented by an ultraviolet-visible absorption spectrum. FIG. 6 shows silver powder (Ag precursor) as a raw material for silver spectroscopy, nanoporous silver (0h) as a raw material for silver spectroscopy, and silver spectroscopy obtained during stirring time of 2, 6, and 12 hours. It is an ultraviolet visible diffuse reflection spectroscopic spectrum of agglomerates of silver nanoparticles (2h, 6h, 12h) and silver microspheres (24h) obtained with a stirring time of 24 hours. Nanoporous silver, which is the raw material for silver powder and silver microspheres, is silver before iodine modification. The aggregate or silver microsphere of silver nanoparticles obtained with a stirring time of 2 to 24 hours is silver after iodine modification. As shown in FIG. 6, all silver before and after iodine modification showed absorption of light at a wavelength of 317 nm corresponding to the plasma edge of silver.
ヨウ素修飾前の銀で観測された波長３８０ｎｍの非対称の吸光ピークは、粒径約７５ｎｍの銀ナノ粒子の筋状体のプラズモン共鳴に起因する。この非対称性は、銀ナノ粒子の筋状体の形状異方性（細長い形状）に起因する。ヨウ素修飾量の増加に伴って、この波長３８０ｎｍの吸光ピークが赤色側に徐々にシフトし、筋状体中の銀ナノ粒子がより密集したことを示唆した。ナノポーラス銀のヨウ素修飾によって、銀ナノ粒子の凝集が起こり、さらに凝集体中の銀ナノ粒子の表面と析出した銀ナノ粒子島の間で活性部が増え、また、凝集体中の銀ナノ粒子の表面が粗面化し、ＬＳＰＲの特性をさらに向上させることができた。このＬＳＰＲの特性向上は、ローダミン６Ｇ色素のＳＥＲＳ信号により確認された。 The asymmetric absorption peak at a wavelength of 380 nm observed in silver before iodine modification is due to the plasmon resonance of the streaks of silver nanoparticles with a particle size of about 75 nm. This asymmetry is due to the shape anisotropy (elongated shape) of the streaks of silver nanoparticles. As the amount of iodine modification increased, the absorption peak at a wavelength of 380 nm gradually shifted to the red side, suggesting that the silver nanoparticles in the streaks became more dense. Iodine modification of nanoporous silver causes agglomeration of silver nanoparticles, further increasing active parts between the surface of the silver nanoparticles in the agglomerates and the precipitated silver nanoparticle islands, and of the silver nanoparticles in the agglomerates. The surface was roughened, and the characteristics of LSPR could be further improved. This improvement in the characteristics of LSPR was confirmed by the SERS signal of the rhodamine 6G dye.
図７は、実施例の各種試料のＳＥＲＳスペクトルである。図７（ａ）は、撹拌時間２〜２４時間で得られた銀ナノ粒子の凝集体または銀ミクロスフェアにローダミン６Ｇを載せたときのＳＥＲＳスペクトル（２ｈ、６ｈ、１２ｈ、２４ｈ）、銀ミクロスフェアの原料のナノポーラス銀にローダミン６Ｇを載せたときのＳＥＲＳスペクトル（０ｈ）、撹拌時間２時間で得られた銀ナノ粒子の凝集体に水を載せたときのＳＥＲＳスペクトル（２ｈ，ｗａｔｅｒ）、および銀ミクロスフェアの原料のナノポーラス銀に水を載せたときのＳＥＲＳスペクトル（０ｈ，ｗａｔｅｒ）である。 FIG. 7 is a SERS spectrum of various samples of the example. FIG. 7A shows the SERS spectra (2h, 6h, 12h, 24h) when Rodamine 6G is placed on an aggregate of silver nanoparticles or silver microspheres obtained with a stirring time of 2 to 24 hours, and silver microspheres. SERS spectrum (0h) when Rhodamine 6G was placed on the raw material nanoporous silver, SERS spectrum (2h, water) when water was placed on the aggregate of silver nanoparticles obtained with a stirring time of 2 hours, and silver. It is a SERS spectrum (0h, water) when water is placed on nanoporous silver which is a raw material of microspheres.
図７（ａ）に示すように、銀ミクロスフェアの原料のナノポーラス銀に弱い測定レーザー出力（０.１５ｍＷ）を印加したとき、ローダミン６Ｇに基づくわずかな信号が観察された。しかし、ＳＥＲＳ信号は、撹拌時間の増加とともに徐々に増加し、撹拌時間２４時間で得られた銀ミクロスフェアでは高水準に達した。さらに、ナノポーラス構造中の銀ナノ粒子が強固であるため、銀ミクロスフェアは、標的分子を電気的に濃縮や吸着する電極基材上に、簡単に貼り付けることができる。 As shown in FIG. 7 (a), when a weak measurement laser output (0.15 mW) was applied to nanoporous silver, which is a raw material of silver microspheres, a slight signal based on Rhodamine 6G was observed. However, the SERS signal gradually increased with increasing stirring time and reached a high level in the silver microspheres obtained with a stirring time of 24 hours. Furthermore, since the silver nanoparticles in the nanoporous structure are strong, the silver microspheres can be easily attached onto the electrode substrate that electrically concentrates or adsorbs the target molecule.
図７（ｂ）は、撹拌時間２４時間で得られた銀ミクロスフェアにローダミン６Ｇを載せたときのＳＥＲＳスペクトル（「＋０.４Ｖ，Ｉ2」と「０Ｖ，Ｉ2」）、ヨウ素を含まないエタノールで２４時間撹拌して得られた銀ミクロスフェアにローダミン６Ｇを載せたときのＳＥＲＳスペクトル（＋０.４Ｖ，ｎｏ Ｉ2）、および撹拌時間２４時間で得られた銀ミクロスフェアに水を載せたときのＳＥＲＳスペクトル（＋０.４Ｖ ｉｎ ｗａｔｅｒ，Ｉ2）である。 FIG. 7B shows the SERS spectra (“+ 0.4V, I 2 ” and “0V, I 2 ”) when Rhodamine 6G was placed on the silver microsphere obtained with a stirring time of 24 hours, and did not contain iodine. The SERS spectrum (+ 0.4V, no I 2 ) when Rhodamine 6G was placed on the silver microsphere obtained by stirring with ethanol for 24 hours, and water was placed on the silver microsphere obtained with a stirring time of 24 hours. The SERS spectrum of the time (+0.4 V in water, I 2 ).
図７（ｂ）に示すように、作用電極に正のバイアス電圧（＋０.４Ｖ）を印加したとき、ヨウ素修飾された銀ミクロスフェアに付着したローダミン６ＧのＳＥＲＳ強度は、バイアス電圧を印加しないときのＳＥＲＳ強度の６.５倍であった。この結果は、正に帯電した銀ミクロスフェアが、短時間（１分間）で溶液中のローダミン６Ｇアニオンを引き付けて濃縮するのに有効であることを示している。また、＋０.４Ｖのバイアス電圧を印加したとき、ヨウ素修飾された銀ミクロスフェアのＳＥＲＳ強度は、ヨウ素修飾されていない銀ミクロスフェアのＳＥＲＳ強度と比べて１６倍であった。これは、ヨウ素修飾がＳＥＲＳ強度の向上に寄与していることを示している。なお、バイアス電圧の印可は、CHI インスルメント製のModel 760AC型電気化学ステーションを使用し、白金をカウンター電極、Ａｇ/ＡｇＣｌを参照電極にした三極式を採用した。 As shown in FIG. 7 (b), when a positive bias voltage (+0.4 V) is applied to the working electrode, the SERS intensity of Rhodamine 6G adhering to the iodine-modified silver microsphere is when no bias voltage is applied. It was 6.5 times the SERS intensity of. This result shows that the positively charged silver microsphere is effective in attracting and concentrating the rhodamine 6G anion in solution in a short time (1 minute). Further, when a bias voltage of +0.4 V was applied, the SERS intensity of the iodine-modified silver microsphere was 16 times higher than that of the iodine-modified silver microsphere. This indicates that iodine modification contributes to the improvement of SERS strength. For the application of the bias voltage, a Model 760AC electrochemical station manufactured by CHI Instrument was used, and a three-pole system was adopted in which platinum was used as a counter electrode and Ag / AgCl was used as a reference electrode.
図７（ｃ）は、撹拌時間２４時間で得られた銀ミクロスフェアにローダミン６Ｇを低濃度で載せたときのＳＥＲＳスペクトルで、作用電極に正のバイアス電圧（＋０.４Ｖ）を印加したときとしなかったときのものである。図７（ｃ）に示すように、バイアス電圧を印加しないとき、ローダミン６ＧのＳＥＲＳがほとんど検出できないが、正のバイアス電圧を印加すれば、弱い測定レーザー出力（０.１５ｍＷ）でも９.９×１０-12Ｍの低濃度のローダミン６Ｇを精度よく検出できた。したがって、ヨウ素修飾された銀ミクロスフェアは、ローダミン６Ｇの検出感度をさらに高めるために、電気的にローダミン６Ｇを吸着・濃縮するときに好適に利用できる。 FIG. 7 (c) shows the SERS spectrum when Rhodamine 6G was placed at a low concentration on the silver microsphere obtained with a stirring time of 24 hours, and it was assumed that a positive bias voltage (+0.4 V) was applied to the working electrode. It was when it wasn't there. As shown in FIG. 7 (c), the SERS of Rhodamine 6G can hardly be detected when the bias voltage is not applied, but when a positive bias voltage is applied, even a weak measurement laser output (0.15 mW) is 9.9 ×. Rhodamine 6G with a low concentration of 10-12 M could be detected accurately. Therefore, the iodine-modified silver microsphere can be suitably used when electrically adsorbing and concentrating rhodamine 6G in order to further increase the detection sensitivity of rhodamine 6G.
ヨウ素修飾が銀ミクロスフェア形成過程に及ぼす影響をさらに明確にするため、ヨウ素を含まないエタノールでナノポーラス銀を処理した。形成速度は下がるものの、銀ミクロスフェアが形成された。ヨウ素を含まないエタノールで１０ｍｇのナノポーラス銀から構成される破片を撹拌処理した結果、ヨウ素修飾されていない銀ミクロスフェアの収率（約６１％）は、ヨウ素修飾された銀ミクロスフェアの収率（９５％以上）より少なかった。また、ヨウ素修飾されていない銀ミクロスフェアの大きさ（約２００ｎｍ）は、ヨウ素修飾された銀ミクロスフェアの大きさ（約５００ｎｍ）より小さかった。 To further clarify the effect of iodine modification on the silver microsphere formation process, nanoporous silver was treated with iodine-free ethanol. Although the formation rate decreased, silver microspheres were formed. As a result of stirring the debris composed of 10 mg of nanoporous silver with iodine-free ethanol, the yield of iodine-unmodified silver microspheres (about 61%) was the yield of iodine-modified silver microspheres (about 61%). It was less than 95%). Moreover, the size of the iodine-modified silver microsphere (about 200 nm) was smaller than the size of the iodine-modified silver microsphere (about 500 nm).
本発明の銀ミクロスフェアは、低濃度の汚染物質を検出する表面増強ラマン散乱用のセンシング基板、直接メタノール型燃料電池等のミニ反応場、および各種マイクロデバイスなどに応用できる。 The silver microsphere of the present invention can be applied to a sensing substrate for surface-enhanced Raman scattering that detects low-concentration contaminants, a mini reaction field such as a direct methanol fuel cell, and various microdevices.
Claims (6)
前記銀の凝集体を、液体と混合して、撹拌する工程と、
を有する銀ミクロスフェアの製造方法。 A step of immersing an alloy of silver and an acid-soluble metal in the acid, removing the acid-soluble alloy to bond silver nanoparticles, and obtaining a silver aggregate having pores.
The aggregate of the silver, is mixed with a liquid, a step of stirring,
A method for manufacturing silver microspheres.
前記液体がヨウ素溶液である銀ミクロスフェアの製造方法。 In claim 1 ,
A method for producing silver microspheres in which the liquid is an iodine solution.
前記銀の凝集体を予め分散させた分散液を超音波処理した後に、前記ヨウ素溶液と混合する銀ミクロスフェアの製造方法。 In claim 2 ,
A method for producing silver microspheres, in which a dispersion liquid in which silver aggregates are dispersed in advance is ultrasonically treated and then mixed with the iodine solution.
前記銀の凝集体と前記液体の混合物を２時間以上撹拌する銀ミクロスフェアの製造方法。 In any of claims 1 to 3 ,
A method for producing silver microsphere, in which a mixture of the silver aggregate and the liquid is stirred for 2 hours or more.
前記銀の凝集体と前記液体の混合物を２４時間以上撹拌する銀ミクロスフェアの製造方法。 In claim 4 ,
A method for producing silver microspheres, in which a mixture of the silver aggregate and the liquid is stirred for 24 hours or more.
前記液体がアルコールを含有する銀ミクロスフェアの製造方法。 In any of claims 1 to 5 ,
A method for producing silver microspheres in which the liquid contains alcohol .
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