Ag/Ag2WO4等离子体共振催化剂可见光催化还原CO2

转化CO₂为有机组分是缓解全球变暖和保障持续能源供给的有效方法之一.采用简易的离子交换结合水合肼还原法制备了一系列不同晶相Ag₂WO₄载银(Ag/Ag₂WO₄)的等离子共振光催化剂,并用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜-能量色散X射线光谱(SEM-EDS)、紫外-可见(UV-Vis)吸收光谱和比表面积测试对催化剂进行了表征.较之Ag₂WO₄, Ag/Ag₂WO₄在可见光催化还原CO₂生成CH₄时显示了明显提高的量子产率(QY)、能量投入产出比(EROEI)、转换数(TON),就Ag/α-Ag₂WO₄, Ag/β-Ag₂WO₄和Ag/γ-Ag₂WO₄而言,最佳催化剂为Ag/β-Ag₂WO₄,其实际最佳Ag:Ag₂WO₄摩尔比为4:96,该催化剂还原CO₂为CH₄的QY、EROEI、TON和拟一级反应速率常数分别为0.145%、0.067%、9.61和1.96×10^-6 min^-1.此外,制备的等离子共振Ag/Ag₂WO₄光催化剂在可见光辐照下进行循环反应仍能保持稳定性.局域表面等离子共振效应是强化Ag/Ag₂WO₄光催化剂活性和稳定性的主要原因.

Ag/Ag2WO4 Plasmonic Catalyst for Photocatalytic Reduction of CO2 under Visible Light

The conversion of CO₂ into organic compounds is a promising method to mitigate global warming and assist in sustaining energy resources. A series of plasmonic photocatalysts, comprised of Ag supported on Ag₂WO₄ (Ag/Ag₂WO₄) with different crystalline phases, are fabricated by a facile ion-exchange method and subsequent reduction with hydrazine hydrate. The catalysts are characterized using X-ray diffraction (XRD) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), UV-Vis absorption spectroscopy, and Brunauer-Emmett-Teller analyses. Compared with Ag₂WO₄, the Ag/Ag₂WO₄ exhibits a markedly improved quantum yield (QY), energy returned on energy invested (EROEI), and turnover number (TON) for CO₂ reduction to CH₄ under visible-light irradiation. Among Ag/α-Ag₂WO₄, Ag/β-Ag₂WO₄, and Ag/γ-Ag₂WO₄ catalysts, the highest activity for CO₂ photoreduction to CH₄ is obtained for Ag/β-Ag₂WO₄ with an actual molar composition of 4% Ag and 96% Ag₂WO₄. Correspondingly the QY, EROEI, TON, and pseudo first-order rate constant are 0.145%, 0.067%, 9.61, and 1.96×10^-6 min^-1, respectively. Moreover, the plasmonic Ag/Ag₂WO₄ photocatalysts are stable after repeated reaction cycles under visible-light irradiation. It is proposed that the localized surface plasma resonance effect of surfacedeposited Ag contributed to the enhanced activities and stabilities of the Ag/Ag₂WO₄ photocatalysts.