Visible-light-driven solar fuels: efficient gas-phase CO2 reduction and H2 production with g-C3N4/CoxNi1−xWO4 nano-heterostructures

Abstract

Herein, CoWO₄/g-C₃N₄, NiWO₄/g-C₃N₄, and Co_xNi_1−xWO₄/g-C₃N₄ (x = 0.66, 0.5, 0.33) nanostructures are synthesized via hydrothermal and calcination methods. The structural, electrochemical, and morphological characteristics of each nano-carrier are systematically analyzed. The fabricated heterostructures exhibit promising activities towards photocatalytic gas-phase CO₂ reduction and photoelectrochemical (PEC) water splitting under visible light illumination, where the type II heterostructure interface plays a crucial role by enhancing the number of active sites and improving the charge-transfer efficiency, leading to a modified charge transfer pathway. Among the synthesized heterostructures, Co_0.66Ni_0.33WO₄/g-C₃N₄ exhibits the lowest band gap compared to other catalysts, demonstrating superior photocatalytic performance for gas-phase CO₂ conversion, achieving CO selectivity of 3.1% and H₂ production rates of 651 µmol m⁻² s⁻¹ under visible light illumination. Optimal Co loading enhances H₂ production and the solar-to-hydrogen conversion efficiency via PEC solar water splitting, while excessive Ni content may hinder process performance. These findings highlight the potential of the developed materials for solar fuel production via photo(electro)chemical processes.