Copper species-loaded hydrophobic Bi2WO6 for photocatalytic reduction of carbon dioxide with water to methane

Abstract

Bi₂WO₆ is a promising material for photocatalytic CO₂ reduction with water due to its favorable band structure; however, its hydrophilic surface often limits catalytic activity. To address this, we developed a hydrophobic copper species loaded Bi₂WO₆ catalyst, featuring exposed copper species nanoparticles and hydrophobic 2-aminoterephthalic acid-modified regions. This catalyst demonstrates exceptional performance, with apparent quantum yield (AQY) and internal quantum efficiency (IQE) 5.2 and 1.8 times higher, respectively, than pristine Bi₂WO₆, alongside methane selectivity exceeding 50%. The hydrophobic agent prevents water molecules from occupying CO₂ adsorption sites, enhancing CO₂ diffusion to active sites and improving conversion efficiency. Meanwhile, water molecules readily access exposed Cu species, dissociating to produce proton intermediates and oxygen. These protons interact with CO₂-derived intermediates on adjacent Bi₂WO₆ surfaces, promoting methane formation. Additionally, the Cu_xO–Bi₂WO₆ p–n junction facilitates electron migration from Cu_xO to Bi₂WO₆ under irradiation, enhancing CO₂ reduction, while holes migrate to Cu_xO, driving water oxidation. The key innovation lies in the controlled growth of the hydrophobic agent on Bi₂WO₆, ensuring copper species remain exposed to water while hydrophobic regions shield Bi₂WO₆. This design optimizes the reactivity of both CO₂ and water active sites, offering valuable insights for developing efficient photocatalysts for CO₂ reduction.