A 1D/2D S-scheme graphitic carbon nitride homojunction for enhancing photocatalytic hydrogen evolution

Abstract

Graphitic carbon nitride (g-C₃N₄) is a promising photocatalyst for visible-light-driven hydrogen evolution, yet its activity is limited by rapid charge recombination, low surface area, and insufficient light absorption. To overcome these bottlenecks, we designed and prepared an S-scheme g-C₃N₄ homojunction photocatalyst by compositing one-dimensional (1D) g-C₃N₄ nanotubes (TCN) with two-dimensional (2D) sulfur-doped g-C₃N₄ nanosheets (SCN). The optimized 1D/2D composite (TSCN-50) exhibits efficient interfacial charge transfer, as evidenced by XPS, and a prolonged fluorescence lifetime (8.73 ns) compared to SCN (3.94 ns) and TCN (4.80 ns), indicating suppressed carrier recombination. Under visible light irradiation, TSCN-50 exhibits an outstanding hydrogen evolution rate of 3025.7 µmol g⁻¹ h⁻¹, which is 3.0 and 3.6 times higher than those of SCN and TCN, respectively, with excellent stability. Electron spin resonance (ESR) measurements further reveal a charge transfer pathway consistent with the S-scheme homojunction, which preserves and utilizes strongly reducing electrons. This work presents a novel non-metallic 1D/2D S-scheme homojunction strategy to boost the performance of g-C₃N₄-based photocatalysts.