Engineering Vacancy‐Atom Ensembles to Boost Catalytic Activity toward Hydrogen Evolution

The dissociation of water is the rate‐determining step of several energy‐relating reactions due to high energy barrier in homolysis of H‐O bond. Herein, engineering vacancy‐atom ensembles via injecting oxygen vacancy (VO) into single facet‐exposed TiO2‐Pd catalyst to form VO‐Pd ensemble is proposed and implemented. The outstanding activity of as‐prepared catalyst, 1.5‐PdTVO, toward water dissociation is established with a turnover frequency of 240 min−1 in ammonia borane hydrolysis at 298 K. Density functional theory simulation suggests that the VO‐Pd ensemble is responsible for the high intrinsic catalytic activity. Water molecules tend to be dissociated on VO sites and ammonia borane molecules on Pd atoms. Those H atoms from water dissociation on VO combine with H atoms from ammonia borane on Pd atoms to generate H2. This insights into engineering vacancy‐atom ensembles catalysis provide a new avenue to design catalytic materials for important energy chemical reactions.