Facile synthesis of carbon-doped ZnCo2O4/ZnO p-n heterojunction via in situ carbonization of Prussian blue analogue for efficient photocatalytic hydrogen generation

Abstract

Hydrogen is recognized as a clean and efficient energy carrier, and photocatalytic hydrogen generation represents a pivotal technology for sustainable energy development. In this work, a highly active noble metal-free ZnCo₂O₄/ZnO/C composite has been successfully synthesized via in situ carbonization of a ZnCo-based Prussian blue analogue (PBA), exhibiting remarkable photocatalytic hydrogen generation activity. Under simulated solar irradiation, the optimized composite achieves a high hydrogen generation rate of 2039.3 μmol/(g·h), along with excellent stability. The significantly enhanced photocatalytic activity originates from a unique S-scheme heterojunction charge transfer mechanism and multi-component synergistic effects. Specifically, the intimate interfacial contact among graphitic carbon, ZnCo₂O₄, and ZnO facilitates efficient separation and migration of photogenerated electron–hole pairs. The S-scheme mechanism not only preserves photogenerated electrons with strong reduction capability but also enhances charge carrier utilization. Furthermore, the graphitic carbon improves the electrical conductivity and light-harvesting capability. These factors are responsible for the remarkable photocatalytic performance and good stability. This work provides a compelling demonstration of utilizing PBA-derived carbonization as a versatile platform for fabricating efficient, stable, and scalable photocatalysts for practical hydrogen production.