The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we desi...The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we designed and constructed a 2D/2D/2D layered heterojunction photocatalyst with cascaded 2D coupling interfaces.Experiments using electron spin resonance spectroscopy,ultraviolet photoelectron spectroscopy,and in-situ irradiation X-ray photoelectron spectroscopy were conducted to confirm the 2D layered CdS/WO_(3) step-scheme(S-scheme)heterojunctions and CdS/MX ohmic junctions.Impressively,it was found that the strong interfacial electric fields in the S-scheme heterojunction photocatalysts could effectively promote spatially directional charge separation and transport between CdS and WO_(3) nanosheets.In addition,2D Ti_(3)C_(2) MXene nanosheets with a smaller work function and excellent metal conductivity when used as a co-catalyst could build ohmic junctions with Cd S nanosheets,thus providing a greater number of electron transfer pathways and hydrogen evolution sites.Results showed that the highest visible-light hydrogen evolution rate of the optimized MX-Cd S/WO_(3) layered multi-heterostructures could reach as high as 27.5 mmol/g/h,which was 11.0 times higher than that of pure CdS nanosheets.Notably,the apparent quantum efficiency reached 12.0% at 450 nm.It is hoped that this study offers a reliable approach for developing multifunctional photocatalysts by integrating S-scheme and ohmic-junction built-in electric fields and rationally designing a 2D/2D interface for efficient light-to-hydrogen fuel production.展开更多
文摘The rapid recombination of photo-generated electron-hole pairs,insufficient active sites,and strong photocorrosion have considerably restricted the practical application of Cd S in photocatalytic fields.Herein,we designed and constructed a 2D/2D/2D layered heterojunction photocatalyst with cascaded 2D coupling interfaces.Experiments using electron spin resonance spectroscopy,ultraviolet photoelectron spectroscopy,and in-situ irradiation X-ray photoelectron spectroscopy were conducted to confirm the 2D layered CdS/WO_(3) step-scheme(S-scheme)heterojunctions and CdS/MX ohmic junctions.Impressively,it was found that the strong interfacial electric fields in the S-scheme heterojunction photocatalysts could effectively promote spatially directional charge separation and transport between CdS and WO_(3) nanosheets.In addition,2D Ti_(3)C_(2) MXene nanosheets with a smaller work function and excellent metal conductivity when used as a co-catalyst could build ohmic junctions with Cd S nanosheets,thus providing a greater number of electron transfer pathways and hydrogen evolution sites.Results showed that the highest visible-light hydrogen evolution rate of the optimized MX-Cd S/WO_(3) layered multi-heterostructures could reach as high as 27.5 mmol/g/h,which was 11.0 times higher than that of pure CdS nanosheets.Notably,the apparent quantum efficiency reached 12.0% at 450 nm.It is hoped that this study offers a reliable approach for developing multifunctional photocatalysts by integrating S-scheme and ohmic-junction built-in electric fields and rationally designing a 2D/2D interface for efficient light-to-hydrogen fuel production.
