Competitive Adsorption: Reducing the Poisoning Effect of Adsorbed Hydroxyl on Ru Single-Atom Site with SnO 2 for Efficient Hydrogen Evolution.

Ruthenium (Ru) has been theoretically considered a viable alkaline hydrogen evolution reaction electrocatalyst due to its fast water dissociation kinetics. However, its strong affinity to the adsorbed hydroxyl (OH ad ) blocks the active sites, resulting in unsatisfactory performance during the practical HER process. Here, we first reported a competitive adsorption strategy for the construction of SnO 2 nanoparticles doped with Ru single-atoms supported on carbon (Ru SAs-SnO 2 /C) via atomic galvanic replacement. SnO 2 was introduced to regulate the strong interaction between Ru and OH ad by the competitive adsorption of OH ad between Ru and SnO 2 , which alleviated the poisoning of Ru sites. As a consequence, the Ru SAs-SnO 2 /C exhibited a low overpotential at 10 mA cm -2 (10 mV) and a low Tafel slope of 25 mV dec -1 . This approach provides a new avenue to modulate the adsorption strength of active sites and intermediates, which paves the way for the development of highly active electrocatalysts.