Cu nanocrystals coupled with poly (heptazine imide) for synergistically enhanced photocatalytic CH₃SH elimination: Facet engineering strengthened electron pump effect

The efficient separation and utilization of intrinsic carriers in photocatalyst, as well as the adsorption and elimination of target pollutants, are two critical challenges in the development of photocatalytic oxidation technology. Herein, the different crystal facet of Cu (111), Cu (100), Cu (111 +100) were engineered and coupled with Poly (heptazine imide) (PHI) as an emerging photocatalyst for CH3SH elimination under simulated solar light (SSL). Cu (111)/PHI exhibited 87.8% elimination efficiency after 30 min of illumination, significantly higher than that of pure PHI (60.4%), Cu (100)/PHI (71.5%), and Cu (111 +100)/PHI (70.4%). Besides, the photocatalytic performance was maintained at 83.3% after a prolonged reaction time of up to 450 min, indicating that Cu (111)/PHI has good stability and reusability. A comprehensive characterizations study confirmed that Cu (111) exhibited the enhanced surface electron pump effect compared to Cu (100) and Cu (111 +100), facilitating the accelerated extraction and transfer of photogenerated charge carriers. Density functional theory (DFT) calculations revealed that Cu (111) surface active sites can effectively adsorb H2O, O-2, and CH3SH due to unsaturated pairing of d-orbital electrons, thus prompting the activation of H2O, O-2 into reactive oxygen species (center dot OH/center dot O-2(-)/O-1(2)) for the eliminating of adjacent CH3SH. This study presents a new facet engineering approach for the rational design of highly efficient photocatalysts for the elimination of S-VOCs.