物理化学学报 >> 2017, Vol. 33 >> Issue (2): 399-406.doi: 10.3866/PKU.WHXB201611092

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Ag3PO4表面热力学性质及光催化原位过程热动力学的晶面效应

肖明1,黄在银1,2,3,*(),汤焕丰1,陆桑婷1,刘超1   

  1. 1 广西民族大学化学化工学院,南宁530006
    2 广西民族大学,广西林产化学与工程重点实验室,南宁530006
    3 广西高校食品安全与药物分析化学重点实验室,南宁530006
  • 收稿日期:2016-09-08 发布日期:2017-01-12
  • 通讯作者: 黄在银 E-mail:huangzaiyin@163.com
  • 基金资助:
    国家自然科学基金(21273050,21573048)

Facet Effect on Surface Thermodynamic Properties and In-situ Photocatalytic Thermokinetics of Ag3PO4

Ming XIAO1,Zai-Yin HUANG1,2,3,*(),Huan-Feng TANG1,Sang-Ting LU1,Chao LIU1   

  1. 1 College of Chemistry and Chemical Engineering, Guangxi University for Nationalities, Nanning 530006, P. R. China
    2 Key Laboratory of Forest Chemistry and Engineering, Guangxi University for Nationalities, Nanning 530006, P. R. China
    3 Guangxi Colleges and Universities Key Laboratory of Food Safety and Pharmaceutical Analytical Chemistry, Nanning 530006, P. R. China
  • Received:2016-09-08 Published:2017-01-12
  • Contact: Zai-Yin HUANG E-mail:huangzaiyin@163.com
  • Supported by:
    the National Natural Science Foundation of China(21273050,21573048)

摘要:

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RhB 2 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。

关键词: 磷酸银, 表面热力学, 原位光量热, 光催化, 晶面效应

Abstract:

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.

Key words: Ag3PO4, Surface thermodynamics, In-situ photocalorimeter, Photocatalysis, Facet effect

MSC2000: 

  • O642