Oxygen modification optimizes hydrogen/hydroxyl binding energy and interfacial water structure for enhanced hydrogen evolution and oxidation reactions
Platinum (Pt) is the benchmark catalyst for the hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR) in acidic electrolytes, but its performance in alkaline media is limited by excessively strong hydrogen binding energy (HBE). Here, we report oxygen-modified ultrasmall RuCu nanocrystals (RuCu/C-200) as an efficient catalyst for both alkaline HER and HOR. The RuCu/C-200 catalyst exhibits excellent HER activity with an overpotential of 9 mV at 10 mA cm−2 and a Tafel slope of 19.7 mV dec−1. For HOR, it achieves a 4.2-fold higher exchange current density than the unannealed sample. Mechanistic studies reveal that the optimized HBE, hydroxyl binding energy (OHBE), and strongly hydrogen-bonded interfacial water, induced by oxygen modification, are the intrinsic determinants of the improved catalytic activity. This work underscores the potential of combining nanoscale structural design with oxygen modification to develop high-performance Ru-based electrocatalysts for both alkaline HER and HOR.