Facile syntheses and in-situ study on electrocatalytic properties of superaerophobic CoxP-nanoarray in hydrogen evolution reaction

Transition metal phosphides (TMPs) have drawn considerable attention as a result of their high catalytic activities for the hydrogen evolution reaction (HER). In this work, a three-dimensional (3D) porous CoxP ordered nanoarray structure was successfully deposited on nickel foam (denoted as NF@CoxP, 1 <_ x <_ 2) via a strategy involving facile gamma ray irradiation and annealing without the use of reducing agent. By modulating the annealing temperature in the synthetic process for NF@CoxP, 3D porous ordered nanoarray composites exhibiting inherently superhydrophilic and superaerophobic properties were produced, the physical properties were confirmed with the use of various in-situ test techniques. The superhydrophilic properties of NF@CoxP help to increase the rate of ion transfer between the CoxP and the electrolyte. Additionally, in-situ verification of the superaerophobic properties showed that they are beneficial for quick release of the generated H2 bubbles from the surface of NF@CoxP electrode, which was analyzed by coupling a 3D confocal microscope with an electrochemical workstation for the first time. As expected, when the resulting NF@CoxP composites were employed as catalyst electrodes for the HER in a 1 M KOH electrolyte, the 3D porous ordered nanoarray structure exhibited an overpotential of 272 mV at the current density of 200 mA cm-2, which was much higher than those of commercial 20%Pt/C catalysts. Therefore, the synthetic strategy for producing NF@CoxP composites with 3D porous ordered nanoarray structures showed high potential for application in the HER.

Automated summary

Transition metal phosphides (TMPs) have attracted attention for their high catalytic activities in the hydrogen evolution reaction (HER). By depositing a three-dimensional porous CoxP nanoarray structure on nickel foam, the NF@CoxP composites exhibited superhydrophilic and superaerophobic properties, benefiting the ion transfer rate and quick release of H2 bubbles during the HER process.