Bond-Competition-Driven Enhancement of Surface Basicity and Interfacial Interaction to Boost Photocatalytic Syngas...

The adsorption and photocatalytic conversion of CO₂ molecules to mitigate atmospheric greenhouse gas concentrations and manufacture value-added chemicals require efficient CO₂ reduction reaction catalysts. In this study, a surface bond competition approach was developed to obtain high-performance CO₂ adsorbents and syngas production photocatalysts via the sulfurization-driven enhancement of surface basicity and interfacial interaction. The heat treatment of Mg-Al-layered double hydroxide nanosheets under a flow of CS₂ yielded sulfur-doped MgO/MgAl₂O₄S_x nanosheets. The sulfur-doping-induced enhancement of surface basicity originated from the increased electron density on oxygen through competition with covalent metal-sulfur bonds, substantially enhancing the CO₂ adsorptivity. The sulfur-doped MgO/MgAl₂O₄S_x nanosheets acted as effective hybridization matrices for ZnIn₂S₄ nanoplates, boosting their activity for photocatalytic syngas production (i.e., ≈3.3 mmol g^-1 h^-1 with the ratio of CO/H₂ = 2.2). Density functional theory calculations revealed that hybridization with MgO/MgAl₂O₄S_x nanosheets was effective in lowering both the adsorption energy of CO₂ and the energy barrier for the conversion of *COOH to *CO. Systematic in situ spectroscopic investigations highlighted that the hybridization with MgO/MgAl₂O₄S_x enhanced Lewis acid-base interaction between ZnIn₂S₄ and absorbed CO₂, and the contribution of associative pathways, which were attributed to sulfur-doping-assisted reinforcement in interfacial electronic coupling between hybridized components.