Boosting alkaline hydrogen evolution performance by constructing ultrasmall Ru clusters/Na⁺, K⁺-decorated porous carbon composites

The construction of efficient and durable electrocatalysts with highly dispersed metal clusters and hydrophilic surface for alkaline hydrogen evolution reaction (HER) remains a great challenge. Herein, we prepared hydrophilic nanocomposites of Ru clusters (~ 1.30 nm) anchored on Na⁺, K⁺-decorated porous carbon (Ru/Na⁺, K⁺-PC) through hydrothermal method and subsequent annealing treatment at 500 °C. The Ru/Na⁺, K⁺-PC exhibits ultralow overpotential of 7 mV at 10 mA·cm⁻², mass activity of 15.7 A·mg_Ru⁻¹ at 100 mV, and long-term durability of 20,000 cycles potential cycling and 200 h chronopotentiometric measurement with a negligible decrease in activity, much superior to benchmarked commercial Pt/C. Density functional theory based calculations show that the energy barrier of H–OH bond breaking is efficiently reduced due to the presence of Na and K ions, thus favoring the Volmer step. Furthermore, the Ru/Na⁺, K⁺-PC effectively employs solar energy for obtaining H₂ in both alkaline water and seawater electrolyzer. This finding provides a new strategy to construct high-performance and cost-effective alkaline HER electrocatalyst.