The controllable synthesis of NiO/Ni/C nanosheets via pulsed plasma in ethylene glycol solution for oxygen evolution electrocatalysis

Abstract

NiO-based composites exhibit high catalytic activity for the oxygen evolution reaction (OER). Herein, high-performance NiO/Ni/C nanosheet catalysts were obtained by liquid-phase pulsed plasma (LPP), which was generated between two nickel electrodes in ethylene glycol (EG) solution by a homemade high-voltage pulse power supply. Melted nickel nanodrops were ejected from nickel electrodes which were bombarded by the energetic plasma. Simultaneously, high-temperature nickel nanodrops promoted the decomposition of the organics which were converted in the EG solution by the catalysis of LPP and formed hierarchical porous carbon nanosheets. Due to the high surface energy of the hierarchical porous carbon nanosheets, the spherical particles of Ni/NiO were adsorbed on the surface to compose the NiO/Ni/C composites. The pore size distribution of the composites could be controlled with different EG concentrations. When the EG concentration was 10 vol% (EG30), the composites possessed a H2 + H2 + H3 type pore size distribution and maximum active site area, leading to an exceptional OER activity (289.2 mV overpotential at 10 mA cm⁻²).