1D metal-dithiolene wires as a new class of bi-functional oxygen reduction and evolution single-atom electrocatalysts

Discovering low-cost, durable and highly active electrocatalysts with reduced use of precious platinum group metals (PGM) as catalysts for the hydrogen evolution reaction (HER), the oxygen reduction reaction (ORR), and the oxygen evolution reaction (OER) is a key step for large-scale adaptation of fuel cells, electrolyzers, and metal-air batteries. Here we explore the stability and reaction mechanisms of synthesized one-dimensional transition metal dithiolene wire (TM-DWs, TM = Cr - Cu, Rh, Ir, Pt, Pd) for the ORR and the OER in acid solution by density functional theory (DFT) calculations. Our calculations reveal that CoDW intrinsically exhibits high catalytic activity for bi-functional ORR/OER with low limiting overpotentials (g) of 0.46/0.45 V via four-electron reactions. These low limiting overpotentials arise from modified scaling relations by strengthening the binding free energy of OOH* compared to OH* on TM-DWs, yielding universal minimum ORR/OER overpotentials of g = 0.28/0.22 V, remarkably decreased compared to both metal and oxide surfaces (gideal = 0.37 V). By applying uni-axial strain, the adsorption strength of reaction intermediates on TM reactive sites can be optimized due to shifts in d-band centers. Our findings provide valuable insight into rational design of non-precious metals based electrocatalysts, and demonstrate a new strategy of tuning adsorptions via uni-axial strain to develop efficient bifunctional electrocatalysts of ORR/OER under optimal conditions. (C) 2020 The Author(s). Published by Elsevier Inc.

Automated summary

In this study, we investigate the stability and reaction mechanisms of synthesized one-dimensional transition metal dithiolene wires for the oxygen reduction reaction and the oxygen evolution reaction in acid solution using density functional theory calculations. Our results show that CoDW exhibits high catalytic activity for bi-functional ORR/OER with low limiting overpotentials through four-electron reactions, and by applying uni-axial strain, the adsorption strength of reaction intermediates on transition metal reactive sites can be optimized. These findings provide valuable insights into the rational design of non-precious metal-based electrocatalysts and suggest a new strategy of tuning adsorptions via uni-axial strain to develop efficient bifunctional electrocatalysts for ORR/OER.