Single metal atoms supported on N-doped 2D M₂C MXenes: an efficient electrocatalyst for overall water splitting

Single-atom catalysts (SACs) are widely used as catalysts for overall water splitting due to their maximum utilization of surface active sites. However, until now, efficient SACs for water splitting are still lacking. Herein, a systematic screening of the overall water splitting performance of Fe, Co, and Ni atoms anchored on M2C, nitrogen modified M2C, and Fe and N co-modification M2C MXenes is performed by using first-principles calculations. The results show that Fe/Mo2C exhibits better hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances among the studied TM/Mo2C structures, with the corresponding value of Delta GH* and eta OER being 0.03 eV and 0.66 V, respectively. In addition, there is an obvious volcanic curve relationship between the d-band center (epsilon d) of TM/M2C and the overpotential of the OER (eta OER). Low N doping concentrations (25%) can also adjust the HER and OER activity of M2C. Interestingly, N doping and Fe loading co-modification Mo2C (Fe/N-Mo2C) shows the best HER and OER properties among the studied TM/N-Mo2C structures, with the corresponding Delta GH* and eta(OER) being 0.01 eV and 0.39 V, respectively. The thermodynamics binding energy and dynamics simulation results reveal that TM/M2C and TM/N-M2C are dynamically stable at the reaction temperature. This work shows that Fe/N-Mo2C can be a potential catalyst for overall water splitting.