Single‐Site Mn‐Doped Ru/RuO₂ Heterostructure for Acidic Overall Water‐Splitting

Abstract Acidic overall water‐splitting driven by consistent electricity is an efficient and economical method for producing green hydrogen. However, developing highly active and durable bifunctional electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER) in acidic conditions remains a challenge. Here, single‐atom Mn sites are introduced into Ru/RuO₂ heterostructures (Mn(SAs)‐Ru/RuO₂) as bifunctional electrocatalysts, achieving low overpotentials of 39 and 158 mV at 10 mA cm⁻² for HER and OER, respectively, while maintaining long‐term durability for overall water‐splitting over 500 h at 1.47 V in 0.5 m H₂SO₄. It outperforms most previously reported bifunctional electrocatalysts. Theoretical calculations show that the charge redistribution caused by single‐site Mn dopants optimizes the adsorption of OOH^* and H^* at Ru sites, significantly boosting electrochemical kinetics for both OER and HER. This work presents an effective single‐site metal doping strategy to optimize the charge distribution of bifunctional electrocatalysts for acidic overall water‐splitting.