Facet reorientation in MOF-derived Co₃O₄-NC induced by In_2.77S₄ nanosheet: Unveiling the active centre at p-n heterojunction for efficient CO₂ reduction

Photocatalytic conversion of carbon dioxide (CO₂) to clean fuels or value-added chemicals is one of the most appealing strategies to solve the energy shortage and environmental issues. Herein, we established a highly efficient p-n heterojunction by epitaxially growing nonstoichiometric ultrathin In_2.77S₄ nanosheets over the surface of ZIF-67-derived Co₃O₄-NC under controlled hydrothermal conditions. The resulting Co₃O₄-NC/In_2.77S₄ (COIS-NC) nanocomposite exhibits well-defined high-indexed (004) facet re-orientation in Co₃O₄-NC, due to the lattice-guided epitaxial alignment, which was efficiently used for photocatalytic CO₂ reduction. Such facet alteration, combined with an N-doped carbon matrix and the formation of oxygen vacancies, results in an increased number of low-coordinated Co sites and accelerates interfacial charge dynamics. The prepared COIS-NC heterostructure exhibited remarkable photocatalytic performance for the selective reduction of CO₂ to CO and H₂ under visible light irradiation, via the *COOH intermediate. The COIS-NC nanocomposite displayed an improved CO production rate of 200 μmol g⁻¹ h⁻¹ under illuminated visible light, which was 5.7, 3.6, and 2.3-fold higher than that of pure Co₃O₄, In_2.77S₄, and Co₃O₄-NC materials. The synergy between regulating the electronic structure, defect engineering and heterojunction stimulates redox kinetics and product selectivity. This work offers a simple and effective method for creating effective MOF-derived heterojunction photocatalysts for CO₂ reduction and sustainable carbon-neutral fuel production.