Balancing catalyst-intermediate interactions: Unlocking high-performance MXene-supported catalysts for two-electron water oxidation reaction from single atoms to nanoparticles

Two-electron water oxidation reaction (2e-WOR) provides an eco-friendly and cost-efficient approach to H₂O₂ synthesis. ZnO-based catalysts exhibit outstanding H₂O₂ activity and selectivity. Exploring the relationship between the structure of different zinc-based catalysts and their 2e-WOR performance is crucial for the rational design and development of high-performance catalysts. In this work, MXene (Ti₃C₂T_x) nanosheets were employed as supports to prepare zinc single atoms, ZnO nanoclusters and nanoparticles on MXene. Structural characterization, electrocatalytic evaluation, and density functional theory (DFT) calculations revealed distinct differences in catalyst performance. Zn-SA/MXene and ZnO-NC/MXene exhibit strong interactions with OH radicals, resulting in adsorption energies that greatly exceed the optimal range of −2.4∼−1.6 eV. This excessive interaction hinders efficient hydrogen peroxide production. In contrast, ZnO-NP/MXene achieves a balanced interaction with OH, with adsorption energy approaching the optimal range, leading to superior 2e-WOR activity. These findings highlight the critical role of tuning the interaction strength between active sites and OH radicals to achieve optimal catalytic performance. This work offers valuable theoretical insights and experimental validation for designing high-performance 2e-WOR catalysts, demonstrating that neither excessively strong nor weak interactions are conducive to maximizing efficiency.