Theoretical insights on oxygen electrode reactions of YNxC4-x@Gra with hydroxylation effect

The oxygen electrode reactions (ORR/OER) are the key to electrochemical storage and conversion technologies. In this study, the bifunctional electrocatalytic mechanisms of YNxC4-x@Gra with hydroxylation effect were discussed extensively. Firstly, the configurations with N coordination have good stability. Secondly, YN1C3/ N2C2hex@Gra with unstable coordination environment break the scale relationships between adsorption intermediates and exhibit outstanding OER performance with eta OER of 0.45 V and 0.46 V. Thirdly, YN2C2oppo/ N2C2pen/N3C1OH@Gra with stable coordination environment demonstrate excellent bifunctional activity with eta ORR of 0.48 V, 0.54 V, and 0.53 V and eta OER of 0.71 V, 0.73 V, 0.63 V. Forth, for catalysts with stable coordination environments, there are scale relationships between the adsorption of intermediates, and thus volcanic curves were constructed. Finally, the d-electron number was introduced to predict catalytic performance, saving time and computative costs for screening potential catalyst configurations. All in all, YNxC4-x@Gra catalysts are potential oxygen electrode bifunctional electrocatalysts.