Oxygen‐Bridged Cobalt–Chromium Atomic Pair in MOF‐Derived Cobalt Phosphide Networks as Efficient Active Sites Enabling Synergistic Electrocatalytic Water Splitting in Alkaline Media

• Published in: Advanced science 2024-01, Vol.11 (3), p.e2306678-n/a
• Main Authors: Lv, Zepeng, Zhang, Huakui, Liu, Chenhui, Li, Shaolong, Song, Jianxun, He, Jilin
• Format: Article
• Language: English
• Subjects: bifunctional electrocatalysts; Cobalt; electrocatalysis; Etching; metal‐organic frameworks; Morphology; Nickel; Spectrum analysis; synthesis; water splitting
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.202306678

Electrochemical water splitting offers a most promising pathway for “green hydrogen” generation. Even so, it remains a struggle to improve the electrocatalytic performance of non‐noble metal catalysts, especially bifunctional electrocatalysts. Herein, aiming to accelerate the hydrogen and oxygen evolution reactions, an oxygen‐bridged cobalt–chromium (Co‐O‐Cr) dual‐sites catalyst anchored on cobalt phosphide synthesized through MOF‐mediation are proposed. By utilizing the filling characteristics of 3d orbitals and modulated local electronic structure of the catalytic active site, the well‐designed catalyst requires only an external voltage of 1.53 V to deliver the current density of 20 mA cm−2 during the process of water splitting apart from the superb HER and OER activity with a low overpotential of 87 and 203 mV at a current density of 10 mA cm−2, respectively. Moreover, density functional theory (DFT) calculations are utilized to unravel mechanistic investigations, including the accelerated adsorption and dissociation process of H2O on the Co‐O‐Cr moiety surface, the down‐shifted d‐band center, a lowered energy barrier for the OER and so on. This work offers a design direction for optimizing catalytic activity toward energy conversion. An effective strategy is suggested to greatly strengthen alkaline bifunctional activity and stability of MOF‐derived Co2P catalyst by introducing the oxygen‐bridged trivalent Cr, achieving directional and accelerated adsorption and dissociation of water molecules and a lowered energy barrier for the OER on oxygen‐bridged Cr‐Co (Co‐O‐Cr) collaborative coordination with strong electron coupling.