Harnessing the Cobalt-Catalyzed Hydrogen Evolution Reaction through a Data-Driven Approach

Abstract

The design of cobalt complexes for the hydrogen evolution reaction (HER) has garnered significant attention over the past few decades. To address the limitations of the traditional trial-and-error method, we introduced the strategy of a simplified mechanism-based approach with data-driven practice (SMADP) in this study. Our results indicate that the polypyridyl cobalt complexes of the DPA-Bpy family (DPA-Bpy = N,N-bis(2-pyridinylmethyl)-2,2′-bipyridine-6-methanamine) generally follow the electron transfer (E)–chemical proton transfer (C)–electron transfer (E)–chemical proton transfer (C) pathway in HER. However, the involvement of proton-coupled electron transfer (PCET) in the formation of the [Co^II(L)–H]⁺ intermediate has been observed in the PY₅Me₂ family (PY₅Me₂ = 2,6-bis(1,1-di(pyridin-2-yl)ethyl)pyridine). Furthermore, the hydricity of the [Co^II(L)–H]⁺ intermediate (ΔG_H^–) and the Co^III–H/Co^II–H reduction potential (E_Red^°) are found to be the active descriptors in the cobalt-catalyzed HER. Excellent two-parameter regression models (ΔG_H^– and E_Red^°) for the formation of the H₂ molecule have been obtained (R² = 0.9429 for the DPA-Bpy family and R² = 0.9854 for the PY₅Me₂ family). Our results demonstrate that the SMADP strategy is a groundbreaking method for delineating active descriptors in the cobalt-catalyzed HER. This data-driven approach could also accelerate the design of novel polypyridyl cobalt complexes for enhanced HER.