The first row transition metal-corrole complexes as a single atom catalyst for electrochemical hydrogen evolution reaction: A DFT insight

The electrocatalytic hydrogen evolution reaction, a half-cell reaction (reduction) in water splitting to produce H2 gas, is considered a green and sustainable way to replace the conventional fossil fuels. Developing a highly conductive, robust, and efficient non-precious hydrogen evolution reaction (HER) catalyst is a key step in the hydrogen economy. Therefore, herein, we have evaluated metallocorroles as single-atom catalysts (SAC) for HER. All calculations of M-Corrole (M represents Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) have been carried out by using state-of-the-art density functional theory computations. The thermal and electrochemical stability of metallocorroles is manifested by the calculation of interaction energy and ionization potential (IP), respectively. Using the Gibbs free energy (Delta GH*) of adsorbed hydrogen as the primary descriptor, the efficiency of catalysts has been studied. According to the Sabatier principle (Delta GH* approximate to 0), titanium anchored in the corrole central cavity (Ti@Corrole) shows the best result having Delta GH* of -0.02 eV for Volmer step. This outcome is further analyzed by charge transfer analysis (NBO analysis), and interactions are studied using the quantum theory of atoms in molecules (QTAIM analysis), and noncovalent interactions (NCI analysis). Ab initio molecular dynamics (AIMD) calculations were done to check temperature stability and indicated that the structure is stable on a range of temperatures. In addition to this, mechanistic study is done, which indicates that Ti@corrole and Sc@corrole follow Volmer-Heyrovsky pathway, whereas Cr@corrole and Sc@corrole follow Volmer-Tafel step for hydrogen evolution process.