Mn-doped Ru/RuO2 nanoclusters@CNT with strong metal-support interaction for efficient water splitting in acidic media

Abstract

Preparation of low-cost, highly activity and stable bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic media has great challenges. Here, a series of M-Ru/RuO2@CNT (M = Mn, Cd, Cu) bifunctional catalysts were synthesized by doping and strong metal-support interaction (SMSI) strategies to improve the activity and stability of the catalysts. The experiment results show that the optimized Mn–Ru/RuO2@CNT catalyst with ultra-small particle size (2.5 nm) has the best catalytic performance, and the OER and HER tests at 10 mA cm−2 in 0.5 M H2SO4 solution show excellent overpotentials of 177 mV and 30 mV respectively, which are better than most of the catalysts reported recently. In addition, current densities of 10 mA cm−2 and 100 mA cm−2 can be obtained at 1.43 V and 1.51 V when measuring water splitting and can last up to 100 h at a current density of 100 mA cm−2. And this is the first time to achieve the stability of acid water splitting of Ru-based catalyst under large current density. Density functional theory (DFT) calculations show that after manganese doping, the electronic structure is changed by charge redistribution between doped ions and ruthenium-based catalysts containing heterojunctions, and the binding energy of intermediates is optimized to improve the catalytic activity; the stability of the catalyst is improved by increasing the formation energy of ruthenium vacancy and preventing the formation of ruthenium vacancy.