Dual-driven charge transport enabled by S-scheme heterojunction and solid solution in CdS@N-NiCoO photocatalysts for enhanced hydrogen evolution

Abstract

The integration of S-scheme heterojunctions and solid solutions presents a dual-driven strategy for efficient charge transport, thus facilitating superior spatial separation and mobility of photogenerated carriers for overall enhanced photocatalytic behaviors. In this work, the photocatalysts of CdS@N-NiCoO (CdS@NCO) were rationally designed, by combining the ultrafine CdS nanoparticles with N-doped NiCoO (NCO) porous microrods derived from a metal organic framework (MOF) precursor. It is verified that the incorporated N dopants and Co-induced impurities could optimize the electronic structure of solid solution, thereby enhancing the charge separation and mobility of photogenerated carriers. Moreover, according to the UPS and in-situ XPS analyses, the formed S-scheme heterojunction based on n-type CdS ensures the efficient electron-hole separation with improved redox potentials. The resultant photocatalysts achieve an outstanding hydrogen (H₂) evolution rate of 4632 μmol·g⁻¹·h⁻¹, which is ∼ 26 times to that of pristine NCO, and outperforms those of most NiO- and Co₃O₄-based photocatalysts ever reported. Current work might provide some insights on exploring advanced photocatalyst for efficient and sustainable H₂ production, enabled by the synergistic effect between heterojunctions and solid solutions.