Enhanced Oxygen Reduction Reaction Via Oxygen Vacancy‐Rich Silica‐Supported Ag/Pd Nanoshells

Herein, we demonstrated the fine‐tuning of catalysts’ active phase by employing AgPd nanoshells with distinct Ag/Pd ratios synthesized via a galvanic replacement method for the oxygen reduction reaction (ORR). However, more interestingly, the subsequent immobilization of such Ag/Pd ratios onto silica further influenced the support characteristics, creating an increasing concentration of oxygen vacancies in this typically inert support — a surprising and unparalleled outcome attested by electrochemical impedance spectroscopy, electron paramagnetic resonance, and theoretical calculation. Such a phenomenon promoted obtaining an optimized electro/photocatalyst with exceptional activity, facilitating not just the ORR but also the photochemical water‐splitting reaction. Curiously, adjusting the Ag/Pd ratio also affected the ORR mechanism, which was switched from a 2‐electron to a 4‐electron after optimization. Finally, Ag38Pd62/SiO2, the catalyst with the best proportion, exhibited a remarkable hydrogen production rate of 1039.8 μmol/gcatalyst during 300 minutes of water splitting, surpassing the performance of the conventional Degussa TiO2 P25 catalyst. This study highlights the fine‐tuning of catalysts for the oxygen reduction reaction (ORR) by synthesizing AgPd nanoshells with varying Ag/Pd ratios through a galvanic replacement method. When these ratios were immobilized on silica, an unexpected increase in oxygen vacancies occurred, enhancing the catalyst's activity. The optimized Ag38Pd62/SiO2 catalyst also demonstrated superior hydrogen production in water‐splitting.