Constructing S-Scheme heterojunctions between ReS2 and Cu-Doped NiCo-LDH: A synergistic strategy for boosted photocatalytic hydrogen production

Ni 0.9 Cu 0.1 Co-LDH/15ReS 2 hollow nanocages was constructed. • The introduction of Cu into NiCo-LDH not only enhanced visible light absorption but also effectively suppresses the recombination of photogenerated carriers. • The BEF formed at the interface between Ni 0.9 Cu 0.1 Co-LDH and ReS 2 can facilitate the spatial separation and directional migration of photogenerated carriers. • The mechanism is explained through the complementary combination of experimental analysis and theoretical calculation. • Outstanding operational stability. The pursuit of efficient and stable photocatalysts for solar-driven hydrogen evolution is critical to addressing the global energy crisis. Herein, a novel S-scheme heterojunction is constructed by integrating ReS 2 particles onto Cu-doped NiCo-layered double hydroxide (Ni 1-x Cu x Co-LDH) hollow nanocages, synthesized via an “etch and grow” method using ZIF-67 as a template. The optimized Ni 0.9 Cu 0.1 Co-LDH/15ReS 2 composite achieves a hydrogen precipitation rate of 4.17 mmol g −1  h −1 under the illumination of visible light, which is 5.48-fold and 3.11-fold higher than those of pristine NiCo-LDH and ReS 2 , respectively. This performance improvement is attributed to the synergy of three key factors. (i) Cu doping effectively modulates the electronic structure of the LDH, introduces defect levels to narrow the bandgap (from 2.1 eV to 1.9 eV) for enhanced visible light absorption, and serves as charge balancer to suppress carrier recombination. (ii) The formation of an ordered heterostructure between Ni 0.9 Cu 0.1 Co-LDH and ReS 2 at their interface creates a built-in electric field that promotes the spatial separation and directional migration of photogenerated charge carriers, markedly reduces the likelihood of their recombination. (iii) The heterojunction exhibits a large specific surface area (109.23 m 2 /g), which effectively exposes more catalytic active sites and prolongs the light propagation path, thereby enhancing surface reaction efficiency and light utilization. The composite also exhibits outstanding stability, retaining 96% of its initial activity after four photocatalytic cycles. Combined theoretical calculations and experimental analyses confirm that the well-matched band alignment and robust interfacial interaction enable effective spatial separation of photogenerated carriers while preserving strong redox potentials. The work demonstrates a very promising strategy for designing high performance LDH-based S-scheme heterojunctions toward sustainable solar-to-chemical energy conversion.