銀/鉑奈米島狀薄膜於電漿子增強的光催化產氫應用
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2021
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近年來全球對於環保課題逐漸重視，積極發展對於環境友善的綠色能源，使得氫能受到廣泛注意。由於產氫反應(Hydrogen evolution reaction, HER)的動力學相當緩慢，需要開發具有良好效率的催化劑，以促進反應發生。貴金屬鉑(Pt)被證實是最佳的產氫催化材料，但其價格高昂並且地球含量稀少限制其發展應用，因此需開發出鉑負載量低且高活性的催化劑。本實驗利用金種誘導生長法，結合金種和多侖試劑(Tollens’ ragent)，在ITO導電玻璃上製作銀奈米島狀薄膜(Ag nanoisland film, Ag-NIF)。通過調控Ag前驅物(AgNO3)、Ag+穩定劑(NH4OH)和還原劑(glucose)的濃度與生長時間等參數來調整島與島間隙(Gap)。接著在溴化十六烷基三甲銨 (CTAB)、抗壞血酸 (AA)、60℃環境下，以銀島狀結構做為模板，利用賈凡尼置換反應(Galvanic replacement)，將鉑還原至銀表面形成銀/鉑奈米島狀薄膜(Ag/Pt-NIF)，利用SEM圖研究奈米結構表面的變化，並利用感應偶合電漿質譜儀(ICP-MS)進行元素定量分析，最後將此材料應用在光催化產氫反應。結果顯示，催化效果最好的樣品Ag/Pt-NIFs (500 μM)置換比例為10:1(Ag: Pt)，鉑含量僅有0.01396 mg/cm2；此外，當Ag/Pt-NIFs置換比例為70:1時，Gap distance約為15.2 nm其光催化產氫增強效果最好，僅需0.00264 mg/cm2鉑負載量，在電流密度為-10 mA/cm2時，與沒照光相比，照光後過電位降低約96 mV。由於銀奈米島狀結構具有強烈的表面電漿共振(Longitudinal surface plasmon resonance, LSPR)效應，其吸收光譜可以從可見光到近紅外光的範圍，實驗結果證明我們的銀/鉑奈米島狀薄膜在光催化可提升產氫的表現。
In recent years, global environmental protection has received great attention, which has promoted the development of green energy, including the hydrogen evolution reaction (HER). Since the kinetics of HER is relatively slow, it is necessary to develop a catalyst with good efficiency to promote the reaction. Platinum (Pt) has been demonstrated to be the best catalytic material for HER. However, the high price and scarcity limit its development and application. A good HER catalyst should have low platinum loading and high activity. In this study, the seed-mediated growth method was used to prepare the Ag-NIFs by combining gold seeds and Tollens’ reagent. The gap distances of the Ag-NIFs can be controlled by adjusting the amount of silver precursor (AgNO3), silver stabilizer (NH4OH) and reducing agent (glucose). For the preparation of Ag/Pt-NIFs, the as-prepared Ag-NIFs were used as the templates to carry out the galvanic replacement reaction in a solution containing CTAB and AA at 60℃. SEM images were used to provide the information of surface changes on the nanostructures, and ICP-MS was used for quantitative analysis of elements. Then, the Ag-NIFs and Ag/Pt-NIFs were used for photocatalytic HER. According to the results, photocatalytic HER of the Ag/Pt-NIFs showed the best plasmon-enhancement, when the gap distance was 15.2 nm. In addition, the platinum loading was 0.00264 mg/cm2. Comparing the results of AM 1.5G irradiation and non-irradiation, at the current density of -10 mA/cm2, the applied overpotential decreased about 96 mV. Based on the LSPR of silver nanostructures, the absorption spectrum can range from visible light to near-infrared light. Our results demonstrated that our Ag/Pt-NIFs reveal the capability of plasmon-enhanced photocatalytic HER.
In recent years, global environmental protection has received great attention, which has promoted the development of green energy, including the hydrogen evolution reaction (HER). Since the kinetics of HER is relatively slow, it is necessary to develop a catalyst with good efficiency to promote the reaction. Platinum (Pt) has been demonstrated to be the best catalytic material for HER. However, the high price and scarcity limit its development and application. A good HER catalyst should have low platinum loading and high activity. In this study, the seed-mediated growth method was used to prepare the Ag-NIFs by combining gold seeds and Tollens’ reagent. The gap distances of the Ag-NIFs can be controlled by adjusting the amount of silver precursor (AgNO3), silver stabilizer (NH4OH) and reducing agent (glucose). For the preparation of Ag/Pt-NIFs, the as-prepared Ag-NIFs were used as the templates to carry out the galvanic replacement reaction in a solution containing CTAB and AA at 60℃. SEM images were used to provide the information of surface changes on the nanostructures, and ICP-MS was used for quantitative analysis of elements. Then, the Ag-NIFs and Ag/Pt-NIFs were used for photocatalytic HER. According to the results, photocatalytic HER of the Ag/Pt-NIFs showed the best plasmon-enhancement, when the gap distance was 15.2 nm. In addition, the platinum loading was 0.00264 mg/cm2. Comparing the results of AM 1.5G irradiation and non-irradiation, at the current density of -10 mA/cm2, the applied overpotential decreased about 96 mV. Based on the LSPR of silver nanostructures, the absorption spectrum can range from visible light to near-infrared light. Our results demonstrated that our Ag/Pt-NIFs reveal the capability of plasmon-enhanced photocatalytic HER.
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表面電漿共振, 銀/鉑奈米島狀薄膜, 賈凡尼置換反應, 產氫反應, Surface plasmon resonance, Ag/Pt nanoisland films, Galvanic replacement reaction, Hydrogen evolution reaction