Blue-light hydrogen production via CdS/g-C3N4 heterojunctions†

Abstract

This study introduced advanced photocatalytic heterojunctions by integrating CdS nanofibers with defect-rich polymeric carbon nitride (g-C₃N₄-V₀). Two g-C₃N₄-V₀ variants (CN1 and CN2) with varying nitrogen vacancy concentrations were synthesized, which enhanced visible and near-infrared light absorption. Eight heterojunctions with different CN1 and CN2 contents (5–20 wt%) were prepared and tested for the hydrogen evolution reaction (HER) in ethanol–water solutions without a Pt co-catalyst. Under optimized conditions (photocatalyst mass: 0.0125 g L⁻¹, light intensity: 10 mW cm⁻²), the CS/CN1-15 and CS/CN2-10 heterojunctions achieved HER rate of 4.43 and 5.25 mmol h⁻¹ g⁻¹, respectively—doubling the efficiency of comparable systems. Their superior performance was attributed to enhanced light absorption, efficient charge separation, and reduced charge transfer resistance. The CS/CN2-10 heterojunction also demonstrated long-term stability, emphasizing its promise for sustainable hydrogen production.