Metal-Doped C3B Monolayer as the Promising Electrocatalyst for Hydrogen/Oxygen Evolution Reaction: A Combined Density Functional Theory and Machine Learning Study

The development of high-efficiency electrocatalysts forhydrogenevolution reduction (HER)/oxygen evolution reduction (OER) is highlydesirable. In particular, metal borides have attracted much attentionbecause of their excellent performances. In this study, we designeda series of metal borides by doping of a transition metal (TM) ina C3B monolayer and further explored their potential applicationsfor HER/OER via density functional theory (DFT) calculations and machinelearning (ML) analysis. Our results revealed that the |& UDelta;G (*H)| values of Fe-, Ag-, Re-, and Ir-doped C3B are approximately 0.00 eV, indicating their excellent HERperformances. On the other hand, among all the considered TM atoms,the Ni- and Pt-doped C3B exhibit excellent OER activitieswith the overpotentials smaller than 0.44 V. Together with their lowoverpotentials for HER (<0.16 V), we proposed that Ni/C3B and Pt/C3B could be the potential bifunctional electrocatalystsfor water splitting. In addition, the ML method was employed to identifythe important factors to affect the performance of the TM/C3B electrocatalyst. Interestingly, the results showed that the OERperformance is closely related to the inherent properties of TM atoms,i.e., the number of d electrons, electronegativity, atomic radius,and first ionization energy; all these values could be directly obtainedwithout DFT calculations. Our results not only proposed several promisingelectrocatalysts for HER/OER but also suggested a guidance to designthe potential TM-boron (TM-B)-based electrocatalysts.