Exploring efficient Pd-based single-atom catalyst on Sc2CO2 MXene by strain engineering

MXenes have exhibited significant potential in energy storage and conversion technologies for their superior structural stability, rich active sites, and metallic conductivity. We investigated the structural stability and electrocatalytic activity of Pd-doped Sc 2 CO 2 MXene under biaxial strain by density functional theory. Negative formation energies and surface free energies of all configurations confirm their structural stability. Pd-Sc 2 CO 2 monolayers under 4% and 6% strains have better electrocatalytic activity with the overpotential of oxygen evolution reaction (OER) comparable with the benchmark in acidic media. In alkaline media, Pd-Sc 2 CO 2 under tensile strains are promising electrochemical catalysts, especially for Pd-Sc 2 CO 2 under +6% strain with an overpotential lower than the benchmarks. Pd-Sc 2 CO 2 under strain also exhibits excellent catalytic activity of hydrogen evolution reaction (HER), with the overpotential close to 0 V under −6% strain. The origin of electrocatalytic performance is further explored by crystal orbital Hamiton population (COHP), charge state, and the adsorption energies of intermediates under strain. This work can help to design and develop high-performance electrocatalysts based on MXenes for energy applications.