Computational screening and investigation of ligand effect on TM single atom catalyst for hydrogen evolution reaction

Here, we studied the stability, electronic characteristics, and HER catalytic performance of transition metal single atom catalysts, both with and without the presence of chlorine ligand. The findings indicate that all catalysts, except for Au, Au-Cl, Ag, Ag-Cl, are thermodynamically stable. We found 3d transition metals are more stable than those in the 4d and 5d series. Ag-Cl, Sc, Ag, Fe-Cl, and Cr-Cl have the poorest electrochemical stability. We found a negative Pearson correlation between Fermi energy and formation energy for TM-Cl, which is opposite to the trend observed for bare TM catalysts. The higher HER activity of chlorine bonded system for the early 3d TM suggests that the downshifting of the d-band center facilitates the activity. We also observed a periodic trend in the d-band center for both TM and TM-Cl systems. Mn-Cl, Cr-Cl, Ti-Cl, Fe-Cl, V-Cl and Zn emerged as the superior catalysts in our study series.