Using electrochemical methods to study the promotion mechanism of the photoelectric conversion performance of Ag-modified mesoporous g-C3N4 heterojunction material

• Ultrafine Ag particles were for the first time used to modify mg-C3N4.
• Electrochemical methods were used to study the performance promotion mechanism.
• Modifying mg-C3N4 with Ag improved the photocatalytic degradation efficiency.
• Ag modification significantly increased the electron mobility of mg-C3N4.

Silver (Ag) nanoparticles are successfully modified onto mesoporous graphitic carbon nitride (mg-C3N4) by photo-assisted reduction. Modifying mg-C3N4 with Ag significantly increases the photoelectric conversion performance. The promotion mechanism is studied through electrochemical methods for the first time. Modifying mg-C3N4 with Ag also increases the conductivity and lowers the energy barrier of the interface reactions. A heterojunction electric field, forms on the interface between the modified Ag and mg-C3N4, enhances the separation efficiency of photogenerated electron–hole pairs. The enhanced separation efficiency thus prolongs the lifetime of the photogenerated electrons and significantly improves the photoelectric conversion performance of mg-C3N4. Furthermore, Modifying mg-C3N4 with Ag significantly improves the adsorption capacity and photocatalytic degradation efficiency. Smaller Ag nanoparticles are much more effective than larger ones in improving photoelectric conversion performance.

mg-C3N4 has a very high application potential in the area of the photocatalytic degradation of organic pollutants and hydrogen production from water splitting. Currently, the low electron mobility and the weak interfacial reaction ability of mg-C3N4 limited its widespread application. Modifying mg-C3N4 with noble metals, such as Ag, Au and Pd, can significantly improve its photocatalytic capability. However, few studies has performed to investigate the photocatalytic promotion mechanism. In this paper, the authors prepared Ag-modified mesoporous mg-C3N4. Flatband potential, interfacial reaction capability and electron mobility, which are closely related with photocatalytic properties, are studied and characterized using electrochemical methods for the first time. Modifying mg-C3N4 with Ag significantly increased the conductivity, lowered the energy barrier of the interface reactions and enhanced the separation efficiency of photogenerated electron–hole pairs.Figure optionsDownload as PowerPoint slide