Synergistic design of dual S-scheme heterojunction Cu2O/ Ni2Al-LDH@MIL-53(Fe) for boosting photocatalytic hydrogen evolution

The development of heterojunctions is a proven strategy to augment the photocatalytic efficiency of materials. However, the enhancement in charge transfer facilitated by a single heterojunction is inherently constrained. To overcome these limitations, we synthesized a dual S-scheme heterojunction ternary composite photocatalyst, Cu2O/Ni2Al-LDH@MIL-53(Fe), designed for efficient visible-light-driven hydrogen (H2) production. The composite catalyst demonstrated a remarkable H2 production rate of 2093.9 mu mol center dot g- 1 center dot h- 1 , which is 4.0-fold greater than that of pristine Cu2O (530.5 mu mol center dot g- 1 center dot h- 1 ), 56.7-fold higher than that of Ni2Al-LDH (36.9 mu mol center dot g- 1 center dot h- 1 ), and 5.9-fold superior to the single S-scheme heterojunction Ni2Al-LDH@MIL-53(Fe) (353.8 mu mol center dot g- 1 center dot h- 1 ). The improved photocatalytic performance is ascribed to the synergistic electrostatic forces and coordination interactions between MIL-53(Fe) and in-situ grown Ni2Al-LDH, which establish a closely contacted interface. Additionally, the incorporation of Cu2O mitigates electron transfer resistance and diminishes the recombination rate of photogenerated charge carriers. The engineered dual S-scheme heterojunction significantly increases the charge transfer pathways for photogenerated charge carriers and introduces minimal interfacial resistance, thus achieving efficient charge transfer. Comprehensive experimental characterizations and density functional theory (DFT) calculations substantiate that the migration of photogenerated electrons adheres to the dual S-scheme heterojunction mechanism. This work provides a design concept that integrates a surface in-situ growth strategy with heterojunction engineering, offering a novel approach for the fabrication of advanced photocatalytic composite materials.