Engineering the Local Electronic Microenvironment via Interfacial Chelation for Efficient CO₂ Photoreduction Toward CH₄.

Abstract

The photocatalytic conversion of CO₂ into hydrocarbons using sustainable solar energy offers a promising strategy to address the global energy crisis and achieve carbon neutrality. However, conventional p-block photocatalysts are often limited by inefficient electron transfer, which restricts the reaction to a two-electron reduction pathway, primarily yielding CO and impeding the formation of high-value hydrocarbons like CH₄. Herein, we construct a novel BiOCl-BiO(HCOO) heterostructure (denoted as BiOCH), which features interfacial chelating interactions between the [Bi₂O₂]² ⁺ and [HCOO]^- layers within the BiO(HCOO) component, for efficient photocatalytic CO₂ reduction to CH₄. This unique heterostructure broadens the light absorption spectrum and facilitates the separation of photoinduced charges. More importantly, the interfacial Bi─O chelation in BiO(HCOO) modulates the local electronic microenvironment of Bi sites. Mechanistic studies reveal that this modulation enhances the coupling between the C-2p orbital of the ^*CHO intermediate and the Bi-p orbital, thereby lowering the Gibbs free energy barrier for the critical ^*CO-to-^*CHO step and promoting CH₄ generation. Consequently, the optimized BiOCH catalyst achieves a remarkable CH₄ production rate of 42.95 µmol·g^- ¹·h^- ¹ with a high electron selectivity of 95.38%. This work provides a novel design strategy of organic-inorganic hybrid layered structures for steering photocatalytic CO₂ reduction toward value-added hydrocarbons.