贵金属负载TiO_2对光催化还原CO_2选择性的影响

Effect of noble metals loaded TiO_2 on the selectivity of photocatalytic CO_2 reduction

利用光沉积方法在TiO2表面分别负载1%(质量分数)Pt、Pd、Au和Ag助催化剂。用TEM、XRD、UV-vis等技术对催化剂进行了表征,并利用连续瞬态电流时间响应和线性扫描伏安法等电化学方法,对贵金属负载的TiO2光催化剂在光照条件下的电流响应强度及电催化析氢电位等特性加以测试。分析了贵金属助催化剂对光催化还原CO2性能的差异。结果表明,负载贵金属助催化剂能显著加速光生电子空穴的分离,降低复合率;另外,助催化剂对还原CO2选择性的顺序为Ag>Au>Pd>Pt。贵金属助催化剂还原CO2的加氢选择性和析氢过电位存在相关性,即越不利于析氢过程的助催化剂,其催化CO2加氢还原产物的选择性越高。

The TiO2 photocatalyst loaded with 1% Pt,Pd,Au,Ag have been prepared by photo deposition method. The catalysts are characterized with X-ray diffraction（XRD）, transmission electron microscopy（TEM）,and UV-vis spectrometer. The electro-catalytic performance for hydrogen production and photo electrochemical performance are investigated by using linear sw eep voltammetry method and continuous transient current-time response method. The performance of photocatalytic CO2 reduction on TiO2 loaded with different noble metals are discussed. The results show that loading noble metal on TiO2 can significantly accelerate the separation of photo production electron and hole and reduce the recombination rate. Furthermore,the sequence of cocatalysts selective reduction for CO2 is Ag Au Pd Pt. A negative correlation betw een the selectivity of CO2 hydrogenation and hydrogen production has been discovered. The cocatalyst which has advantage to hydrogen evolution process goes against the selectivity of CO2 hydrogenation.