RESUMO
Innovative bimetallic materials provide more possibilities for further improving the performance of oxygen evolution reaction (OER) electrocatalysts. However, it is still a great challenge to rationally design bimetallic catalysts because there is not a practical way to decouple the factors influencing the intrinsic activity of active sites from others, thus hindering in-depth understanding of the mechanism. Herein, we provide a rational design of bimetallic Ni, Co two-dimensional polymer model OER catalyst. The well-defined architecture, identical density of active sites and monolayer characteristic allow us to decouple the intrinsic activity of active sites from other factors. The results confirmed that the relative position and local coordination environment has significant effect on the synergistic effect of the bimetallic centres. The highest electrocatalytic activity with the turnover frequency value up to 26.19â s-1 was achieved at the overpotential of 500â mV.
RESUMO
Spinel oxides are promising low-cost catalysts with manifold and controllable physicochemical properties. Trial and error strategies cannot achieve the effective screening of high-performance spinel catalysts. Therefore, unraveling the structure-performance relationship is the foundation for their rational design. Herein, the effects of cations in tetrahedral and octahedral sites on the electronic structures of spinels were systematically investigated using GGA + U calculations based on ACr2O4 (A = Mn, Fe, Co, Ni, and Zn) and Zn/LiB2O4 (B = Cr, Mn, Fe, Co and Ni). The results indicate that the octahedrally coordinated B cations have notable influence on the electronic structures of spinels. The Jahn-Teller active ions Fe2+, Ni2+, Mn3+, Ni3+, Cr4+ and Fe4+ can remarkably reduce the band gaps of spinels and even change their electroconductibilities. These results will provide theoretical insights into the electronic properties of 3d transition metal spinels.