Ag_3PO_4形貌和晶面对Ag/Ag_3PO_4等离子体催化剂光催化还原CO_2的影响

采用简单的离子交换-光还原法制备了3种表面暴露的晶面分别为单一{110}、{100}和{111}晶面的Ag/Ag3PO4等离子体光催化剂,利用X射线衍射、扫描电子显微镜、紫外-可见漫反射光谱、X射线光电子能谱和比表面积测试等技术分别对3种样品的晶相组成、微观形貌和吸光度等进行了表征。所制备催化剂用于可见光照射下光催化还原气相中的CO2生成碳氢化合物,考察了催化剂暴露的晶面与催化还原CO2活性的关系,并探讨Ag/Ag3PO4光催化还原CO2的机理。研究表明,{111}晶面暴露的四面体Ag/Ag3PO4具有最大的光催化还原CO2生成CH3OH的光量子效率、能量投入产出比和转换数。CO2可通过CO2→·CO-2→HCOOH→HCHO→CH3OH途径还原。

Effect of morphology and exposed facets of Ag3PO4 on photocatalytic reduction of CO2 to CH3OH over Ag/Ag3PO4 plasmonic photocatalysts

Different morphology of Ag/Ag₃PO₄ plasmonic photocatalysts enclosed with single {110}, {100} and {111} facets were synthesized by a facile ion-exchang method followed by light-induced reduction. The X-ray powder diffraction, scanning electron microscopy, UV-visible absorption spectra, X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller measurements were employed to investigate the phase structure, micro morphology and absorbance of Ag/Ag₃PO₄ powders. The correlation between photocatalytic activities and exposed facet as well as the mechanism of photocatalytic reduction of CO₂ under visible-light were explored. The results indicated that tetrahedral Ag/Ag₃PO₄ with exposed {111} facets exhibited the superior quantum yield, the ratio of the energy returned on energy invested and the turnover number. CO₂ could be reduced through the process CO₂ → ·CO₂^- → HCOOH → HCHO → CH₃OH.