Enhancing electrocatalytic CO₂ reduction <i>via</i> engineering substrate–cluster interaction

Cu clusters exhibit exceptional performance in the electrocatalytic carbon dioxide reduction reaction (CO₂RR) due to their tunable size. Using first-principles calculations, we systematically investigate the CO₂RR on small Cu_<i>n</i> clusters (<i>n</i> = 3, 8, 13) anchored on a T'-WTe₂ substrate, denoted as Cu_<i>n</i>@T'-WTe₂. Given that the hydrogen evolution reaction (HER) often competes with the CO₂RR, we further investigated the competition between the CO₂RR and HER. Our results show that Cu_<i>n</i>@T'-WTe₂ outperforms pure Cu_<i>n</i> clusters as catalysts, with enhanced CO₂RR activity. The CO₂RR performance of Cu_<i>n</i>@T'-WTe₂ enhances with increasing cluster size, and surpasses the HER activity in Cu₁₃@T'-WTe₂. This enhancement stems from the substrate-cluster interactions, where the buckled "non-uniform surface" of T'-WTe₂ deforms the larger Cu₁₃ cluster, optimizing the CO₂RR efficiency. We propose a potential strategy for WTe₂-supported Cu clusters to boost CO₂RR while suppressing HER by leveraging substrate-supported Cu clusters.