Development of a Direct S‐Scheme 2D/2D g‐C ₃ N ₄ /Co–Al LDH Heterojunction with Integrated CdCO ₃ Nanoparticles for Improved Photocatalytic Hydrogen Generation

Developing visible‐light‐responsive photocatalysts is crucial for sustainable hydrogen production. In this study, a CdCO 3 ‐integrated 2D/2D g‐C 3 N 4 /Co–Al layered double hydroxide (LDH) S‐scheme heterostructure was designed to achieve efficient charge separation and enhanced light utilization. X‐ray photoelectron spectrocopy (XPS), ultraviolet photoelectron spectroscopy, and electron spin resonance analyses confirmed the formation of an S‐scheme junction between g‐C 3 N 4 and Co–Al LDH, while photocurrent and photoluminescence studies revealed improved charge mobility and reduced recombination. The incorporation of CdCO 3 nanoparticles as a cocatalyst further accelerated interfacial electron transfer and strengthened redox activity. Consequently, the optimized heterostructure achieved a 16.1‐fold increase in hydrogen evolution compared with pure g‐C 3 N 4 , demonstrating a strong synergistic effect between S‐scheme charge migration and cocatalyst‐induced modulation. The structure also exhibited excellent stability under visible‐light irradiation. This work presents an effective strategy for constructing advanced multijunction photocatalysts with engineered interfaces, offering valuable insight for next‐generation solar‐to‐hydrogen conversion systems.