High-spin transition metal atoms drive acidic oxygen evolution reactions

Synthesizing transition metal catalysts to replace precious metal ones such as IrO2 and RuO2, achieving efficient acidic oxygen evolution reaction while balancing intrinsic activity, stability, and cost-effectiveness always been a dream pursued by scientists and industrialists, but still remains a challenge. Here, we present an efficient catalytic system formed by graphdiyne-induced high-spin state cobalt-based oxide (HSS-CoOx/GDY) for enhancing the activity and stability of the acidic oxygen evolution reaction. Experimental and theoretical results demonstrate that the bonding of electron-rich sp-hybridized carbon and Co atoms initiates the Jahn-Teller effect of CoO6 octahedra, which regulates the occupied d-orbital of Co atoms and generates the high-spin Co3+. Such spin occupancy breaks the spin-forbidden effect and optimizes the adsorption/desorption ability of HSS-CoOx/GDY toward key reaction intermediates, thereby promoting the coupling of O-O bonds and the evolution of oxygen gas. The proton exchange membrane water electrolyzers constructed based on this catalyst achieve a current density of 1.0 A cm−2 at a low cell voltage of 1.80 V. This research indicates that graphdiyne has the ability to manipulate the electronic spin states of electrocatalysts. Developing non-precious-metal oxygen evolution reaction catalysts to replace precious metal components is a promising strategy to reduce the cost, yet it remains a challenge. Herein, the authors report a catalyst system with high-spin Co3 + , achieving efficient acidic water oxidation.