Cubic{ 100},tetrahedral{111},and rhombic dodecahedral{110} Ag3PO4 microcrystals were synthesized via a facile wet chemical method.Their components,structure,morphology,and photoelectrical properties were characterized by field emission scanning electron microscopy (FE-SEM),X-ray powder diffraction (XRD),ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS),photocurrent and photoluminescence (PL) analyses.The photocatalytic activity of the Ag3PO4 crystallites with different morphologies were investigated under visible illumination using rhodamine B (RhB) as a target contaminant.Meanwhile,the surface molar Gibbs free energy of the Ag3PO4 crystallites was determined by microcalorimetry via transition state theory and the thermochemical cycle principle.The corresponding values for cubic,tetrahedral,and rhombic dodecahedral microcrystals were 1.2972,0.9621,and 0.5414 kJ· mol-1,respectively.The heat effect of the in-situ photocatalytic degradation of RhB and heat flow of the stable exothermic stage over the Ag3PO4 crystallites was detected by a LED-photocalorimeter.The results showed that the catalytic activity of Ag3PO4 crystallites and the heat effect and heat flow of the stable exothermic stage were positively correlated with their molar Gibbs free energy.Additionally,the main active species for the photocatalytic degradation of RhB over Ag3PO4 crystallites were determined by trapping experiments and electron paramagnetic resonance (ESR) spectroscopy.%采用湿化学法制备了立方体{100}、四面体{111}和菱形十二面体{110}磷酸银微晶,通过场发射扫描电镜(FE-SEM),X射线粉末衍射(XRD),固体紫外可见漫反射光谱(UV-Vis DRS),光电流,光致发光(PL)对催化剂的组分、结构、形貌及光电性质进行了系统表征.以罗丹明B(RhB)为目标污染物,对不同形貌Ag3PO4微晶的可见光催化活性进行了探究.通过微热量技术结合过渡态理论和热化学循环原理对Ag3PO4的摩尔表面Gibbs自由能进行了测定,其数值分别为1.2972、0.9621、0.5414 kJ·mol-1.采用自主设计的新型LED光-微热量系统获取了Ag3PO4原位光催化降解RhB2 h的热效应和稳定放热阶段的热焓变化率,并对其热谱曲线进行了合理的解析.结果表明,Ag3PO4的催化活性与原位光催化降解RhB的热效应、热焓变化率以及摩尔表面Gibbs自由能皆呈正相关.此外,通过捕获剂实验和电子顺磁共振(ESR)确定了Ag3PO4光催化降解RhB过程的主要活性基团.
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