Immobilizing Bimetallic RuCo Nanoalloys on Few-Layered MXene as a Robust Bifunctional Electrocatalyst for Overall Water Splitting

Doping Co atoms into Ru lattices can tune the electronic structure of active sites, and the conductive MXene can adjust the electrical conductivity of catalysts, which are both favorable for improving the electrocatalytic activity of the catalyst for water splitting. Here, ruthenium-cobalt bimetallic nanoalloys coupled with exfoliated Ti₃C₂T_x MXene (RuCo−Ti₃C₂T_x) have been constructed by ice-templated and thermal activation. Due to the strong interaction between the RuCo nanoalloys and conductive MXene, RuCo−Ti₃C₂T_x not only exhibits an excellent hydrogen evolution reaction (HER) performance with a low overpotential and Tafel slope (60 mV, 34.8 mV dec⁻¹ in 0.5 M H₂SO₄ and 52 mV, 38.7 mV dec⁻¹ in 1 M KOH), but also good oxygen evolution reaction (OER) performance in an alkaline electrolyte (266 mV, 111.1 mV dec⁻¹ in 1 M KOH). The assembled RuCo−Ti₃C₂T_x||RuCo−Ti₃C₂T_x electrolyzer requires a lower potential (1.56 V) than does the Pt/C||RuO₂ electrolyzer at 10 mA cm⁻². A boosted catalytic HER activity from immobilizing the RuCo nanoalloys on MXene was unveiled by density functional theory calculations. This study provides a feasible and efficient strategy for developing MXene-based catalysts for overall water splitting.