Unlocking the Potential of Sub-Nanometer Pd Catalysts for Electrochemical Hydrogen Peroxide Production

The utilization of nanoscale catalysts represents a valuable and promising strategy for augmenting catalytic performance while mitigating the reliance on expensive noble metals. Nevertheless, a significant knowledge gap persists regarding the intricate interplay between catalyst size, physical properties, and catalytic behavior in the context of the oxygen reduction reaction. In this study, the synthesis of precisely controlled palladium catalysts is presented, spanning a wide range from individual atoms to metal clusters and nanoparticles, followed by a comprehensive evaluation of their performance in acidic conditions. The results show a significant increase in H2O2 selectivity of up to 96% with decreasing catalyst size and strategic approaches are identified to eliminate unselective sites, facilitating the attainment of active and selective catalysts. The enhanced selectivity of the catalysts highlights the potential of single atom catalytic sites and can be adapted to improve the performance of various catalytic processes. In this research, size-controlled Pd catalysts are synthesized and their oxygen reduction reaction performance in acidic media evaluated. The findings indicate that decreasing catalyst size leads to a significant increase in H2O2 selectivity of up to 96%. With increasing size, oxygen reduces via a 4 e- pathway. By exploiting the irreversibility of CO adsorption on extended surfaces, individual Pd atoms' intrinsic catalytic activity and selectivity are identified.image