Transition metal single-atom electrocatalysts (SACs) with metal-nitrogen-carbon (M-N-C) configurations have shown great potential in oxygen evolution reactions (OER), and modulating the spin configuration in M-N-C to enhance the spin-sensitive OER energy level is imperative, but it is still a great challenge. Based on this,Professor Hou Yanglong of Peking University, Professor Zhao Yufeng of Shanghai University, Professor Wang Jing of Yanshan University (co-corresponding author) and othersThe local field distortion of the low- and medium-spin transitions caused by the introduction of the main group elements (Mg) into the Fe-N-C structure is reported, and the potential origin of the enhanced OER activity is revealed.
It is found that the large ionic radius mismatch between Mg2+ and Fe2+ causes the deformation of the square local field in the Fen4 plane, which triggers the Fe2+ spin from it (dxy2dxz2dyz1dz21,296 b) to low spin (dxy2dxz2dyz2,0.).95b), thus modulating the thermodynamics of the primitive step by Gibbs free energy. The obtained Mg Fe two-site catalyst exhibits excellent OER activity, with an overpotential of 224 mV at 10 mA cm-2 and an electrolytic voltage of only 1542 V, which is better than the most advanced transition metal SAC available.
In this paper, the local geometric symmetry can be significantly adjusted through the design of metal dual sites and carbon and nitrogen synergistic strategies, and the obtained low-spin Fe2+ exhibits good binding energy to the key reaction intermediate *O, thereby reducing the overpotential of 4E-Oer. This work proposes a promising strategy for manipulating iron spin to improve the electrocatalytic performance of single-atom catalysts, opening up a broad field for exploring low-cost, high-performance catalysts.
improving electrocatalytic oxygen evolution through local field distortion in mg/fe dual-site catalysts. angew. chem. int. ed.,, doi: 10.1002/anie.202314303.