Point-to-face Z-scheme junction Cd0.6Zn0.4S/g-C3N4 with a robust internal electric field for high-efficiency H2O2 production

Abstract

Photocatalytic H₂O₂ evolution has ignited a remarkable spark by virtue of its outstanding strengths of safety, greenness and low cost, while severely hindered by the grievous photoinduced carriers' recombination and sluggish charge migration. Here, we anchored the Cd_0.6Zn_0.4S solid solution nanoparticles on ultrathin g-C₃N₄ for constructing a point-to-face configurated Z-scheme junction via an in situ growth strategy. Such a unique point-to-face structure not only benefits fast interfacial charge migration, but also hinders the agglomeration of Cd_0.6Zn_0.4S nanoparticles. In situ Kelvin-probe force microscopy (KPFM) results and density functional theory (DFT) calculations along with other advanced characterization studies collectively unfold the presence of a strong internal electric field (IEF) between Cd_0.6Zn_0.4S nanoparticles and ultrathin g-C₃N₄, derived from the band potential difference and intimate contact, which serves a robust driving force to markedly accelerate direct Z-scheme charge transfer and carriers' separation. The Z-scheme junction also favors maintaining a strong redox potential, and effectively inhibits the recombination of photoinduced carriers. Thus, point-to-face Z-scheme junction Cd_0.6Zn_0.4S/ultrathin g-C₃N₄ exhibits a remarkable photocatalytic H₂O₂ yield of 1098.5 μmol g⁻¹ h⁻¹, exceeding the majority of CN-based and sulfide-based photocatalysts. This study puts forward promising ideas in manufacturing a Z-scheme junction with a powerful IEF for high-performance photocatalytic H₂O₂ generation.