CsPbI3/Pt-g-C3N4 heterostructures toward efficient photocatalytic dichlorophenol removal

CsPbI 3 /Pt-g-C 3 N 4 Z-scheme heterojunction was created for efficient charge carrier separation. • 1D/2D heterostructure enhances interfacial contact and charge separation. • Pt nanocrystals act as electron mediators guiding directional charge flow. • Coupling photocatalysis with persulfate activation boosts degradation efficiency. • Singlet oxygen identified as the dominant reactive species in the system. A novel Z-scheme photocatalytic system was constructed by bridging graphitic carbon nitride (g-C 3 N 4 ) nanosheets with CsPbI 3 nanowires (NWs) via Pt nanocrystals (NCs) mediators. Comprehensive material characterization verifies that the rational combination of CsPbI 3 NWs and g-C 3 N 4 nanosheets leads to a well-defined 1D/2D heterostructure with intimate interfacial contact. Notably, Pt NCs as highly efficient electron mediators successfully establish a Z-scheme charge transfer pathway and thereby remarkably enhance the separation and migration efficiency of photogenerated carriers. Photoelectrochemical measurement confirms that g-C 3 N 4 /Pt/CsPbI 3 NW composites exhibit substantially elevated photocurrent density and remarkably reduced charge transfer resistance compared with the composites created using CsPbI 3 NCs, indicating the important role of 1D NW structure. Because of well-developed heterostructure and expanding visible light absorption, g-C 3 N 4 /Pt/CsPbI 3 NW composites revealed a degradation efficiency of 71.3% for 2,4-dichlorophenol while that of g-C 3 N 4 /Pt/CsPbI 3 NC composites is 62.9%. The degradation efficiency was further elevated to 82.8% with the introduction of persulfate, forming a coupled photocatalysis advanced oxidation process. Mechanistic studies demonstrate that the construction of Z-scheme heterojunction remarkably enhances the generation of superoxide radicals (·O 2 - ), with a resulting concentration of 12.23 × 10 –7 mol/L. These ·O 2 - species are subsequently converted into singlet oxygen, the primary active agent that works together with ·O 2 - and other radicals to synergistically degrade organic pollutants. These resultssuggest that a highly efficient and stable Z-scheme photocatalyst was created and offer important theoretical and practical guidance for advanced photocatalyst design. Download: Download high-res image (237KB) Download: Download full-size image