Boosting alkaline water splitting and the urea electrolysis kinetic process of a Co3O4 nanosheet by electronic structure modulation of F, P co-doping.

Abstract

Designing non-precious metal electrocatalysts for accelerated electron transfer and richer active site exposure is necessary and challenging to achieve the versatility of electrocatalysts. In this research, a self-grown nanosheet array electrocatalyst on nickel foam with high structural stability is first rationally designed through suitable anionic doping. The combined experimental and theoretical calculations reveal that the F-P-Co3O4/NF material optimizes the adsorption energy of hydrogen/water through electron coupling, and its nanosheet structure provides abundant active sites, accelerating the mass and electron transfer in the reaction process. It is worth noting that the as-developed F-P-Co3O4/NF materials exhibit outstanding catalytic activity for overpotentials of 192 and 110 mV at a current density of 10 mA cm-2 for the oxygen evolution reaction and the hydrogen evolution reaction in 1 M KOH, respectively. More notably, an assembled F-P-Co3O4/NF//F-P-Co3O4/NF alkaline electrolytic cell requires only an ultra-low cell voltage of 1.53 V to achieve a current density of 10 mA cm-2, which is one of the best activities reported so far. Furthermore, F-P-Co3O4/NF also shows excellent performance for urea electrolysis. Theoretical calculations show that the superior activity of the F-P-Co3O4/NF catalyst is attributed to the optimal electron configuration and the lower Gibbs free energy of hydrogen adsorption due to co-doping of P and F. The work provides an alternative solution for the preparation of electrocatalysts with high structural stability, high catalytic activity and multifunction for alkaline water splitting and urea electrolysis.