Piezoelectric Polarization and Empty Conduction Band of Zinc Sulfide: Structure Modulation on Graphitic Carbon Nitride for Carbon Dioxide Reduction to Methane

Abstract Rapid recombination of photoinduced charges on the surface and in the bulk phase of semiconductors severely hinders the photocatalytic performance. The synchronous regulation of photocarriers at different locations is also a huge challenge. With these issues in mind, the simultaneous enhancement of surface and bulk carrier separation of g‐C 3 N 4 for highly selective reduction of CO 2 to CH 4 by coupling with dual functional ZnS is reported. The introduction of ZnS not only acts as a cocatalyst to capture the photogenerated electrons of g‐C 3 N 4 , but also forms a polarization electric field to drive the prompt migration and separation of photogenerated charges from bulk to surface. Under concurrent vibration and visible‐light irradiation, the as‐obtained ZnS/g‐C 3 N 4 demonstrates significantly enhanced piezo‐photocatalytic for CO 2 reduction, which is higher than that of photocatalytic and piezocatalytic performance, respectively. In addition, the selectivity of the reduction products is enhanced through optimization of the mass ratio of ZnS/g‐C 3 N 4 . When the ZnS content is increased to 7.95 wt%, high selectivity (95.7 %) of CO 2 reduction to CH 4 is achieved on ZnS/g‐C 3 N 4 . This work provides a means to regulate the carrier movement pathway and to enhance charge separation in the bulk phase and on the surface of the semiconductor for selective CO 2 conversion.