不同形貌Ag_3PO_4的表面自由能及原位光催化过程的热力学和动力学参数

Thermodynamic and Kinetic Parameters of in-situ Photocatalytic Process with Different Morphologies of Ag_3PO_4 and Their Free Energy

目前，在利用表面能研究纳米催化剂形貌效应时，多以催化剂表面原子排布或不同晶面的夹角与密勒指数间的关系来定性描述表面能高低，或利用密度泛函理论对表面能进行理论计算，但其数值可能会因计算方法和模型不符而与真实值存在偏差，而表面能的实验测定至今仍无精确、可靠、通用的方法．因此发展一种准确获取表面能的普适性方法并与材料的催化性能相关联非常必要．微量热技术能对体系变化过程进行实时监测，通过体系变化过程的热力学和动力学参数获取纳米材料的表面能．将光化学与微量热技术结合，可同时获得光催化原位过程热量及热焓变化率的详细信息，从而实现催化过程热效应与催化降解速率的关联与统一．

A self-designed photomicrocalorimeter was applied to obtain in-situ thermodynamic and kinetic information on photocatalysis degradation of methylene blue （ MB ） over different morphologies of Ag3PO4. The molar surface Gibbs free energies（Gm^s） of the prepared Ag3PO4 were obtained based on the thermokinetic theory and microcalorimetry. The acquired in-situ thermodynamic and kinetic information of the photocatalytic process was successfully associated with Gm^8 and catalytic performance of the prepared Ag3O4 catalyst with different morphologies. The results revealed that the heat effect and enthalpy change rate of the tetrapod, cube and dodecahedron Ag3PO4 increased in order, whereas the Gm^s and catalytic performance of the tetrapod, cube and dodecahedron Ag3PO4 decreased in order.