Enhanced selective reduction of CO₂ to CH₄ over MoS₂/HNb₃O₈ via induced confined coordination-unsaturated MoS active...

The selective conversion of CO₂ into CH₄ poses a significant challenge, primarily attributed to the ultra-stable OCO structure and the multi-electron-accompanied proton reduction process. In this study, we design and synthesize a photocatalyst, MoS₂ rich in S defects modified HNb₃O₈ (DR MoS₂/HNb₃O₈), with an in-plane interface. This configuration involves the homogeneous attachment of S-deficient MoS₂ nanosheets to ultrathin HNb₃O₈ nanosheets. The 2D/2D interface proves advantageous for facilitating electron transfer from HNb₃O₈ to DR MoS₂, thereby promoting the multi-electron conversion process. Simultaneously, the coordination-unsaturated Mo and edged S in DR MoS₂ serve as efficient activation sites for H₂O and CO₂, respectively. The confined active units play a crucial role in generating COOH* intermediates, subsequently leading to a thermodynamically favorable route for CH₄ production. Consequently, the well-designed confined active units in MoS₂ enhance the photocatalytic CO₂ conversion activity, emphasizing selectivity for CH₄ over HNb₃O₈. The optimized sample (DR MoNb-300) attains a remarkable selectivity of 76.8 % for CH₄, with a production rate of 8.6 μmol g^-1 h^-1, surpassing that of defect-free counterparts. This work offers insights into the rational design of active sites, influencing reaction pathways for selectively reducing CO₂.