Structure-Function Relationship of p-Block Bismuth for Selective Photocatalytic CO₂ Reduction

Area of Science:

• Materials Science
• Catalysis
• Photochemistry

Background:

• Selective photocatalytic reduction of carbon dioxide (CO2) to methane (CH4) is crucial for producing high-mass-energy density fuels.
• Current p-block materials face challenges in CH4 selectivity due to suboptimal adsorption of the *CHO intermediate and an undefined structure-function relationship.

Purpose of the Study:

• To elucidate the key reaction steps in CO2 reduction to CH4.
• To establish a structure-function relationship for enhanced CH4 selectivity using p-block materials.
• To develop novel p-block materials for efficient and selective photocatalytic CO2 conversion.

Main Methods:

• Investigated the photocatalytic CO2-to-CH4 conversion mechanism using p-block Bi elements.
• Engineered Bi-oxygen vacancy heterosites to tune the p-band center and electronic structure.
• Analyzed the adsorption energy of the *CHO intermediate and its correlation with CH4 selectivity.

Main Results:

• Discovered a volcano-type structure-function relationship for CO2-to-CH4 conversion, linked to the p-band center of Bi.
• Bi-oxygen vacancy heterosites with a p-band center of -0.64 demonstrated high CH4 selectivity (95.2%) and productivity (17.4 μmol g⁻¹ h⁻¹).
• The heterosites facilitate *CHO adsorption and C-H/C=O bond activation, leading to efficient multielectron transfer for CH4 production.

Conclusions:

• The synergistic effect in Bi-oxygen vacancy heterosites optimizes Gibbs free energy for the *CO-*CHO process.
• This engineered material provides a new strategy for developing p-block elements for selective photocatalytic CO2 conversion.
• The findings offer a new perspective for designing advanced catalysts for sustainable fuel production.