Microwave-Induced Plasma Synthesis of Defect-Rich, Highly Ordered Porous Phosphorus-Doped Cobalt Oxides for Overall Water Electrolysis

Porous materials have emerged as promising candidates for electrocatalytic water splitting due to their abundant reaction sites, interconnected diffusion channels, and facile gas bubble dissipation. The presence of surface defects on electrocatalysts promotes conductivity and diffusion coefficient, thus improving electrochemical performance. Here, an efficient way is described for generating defect-rich, highly ordered macroporous phosphorus-doped cobalt oxides catalysts (Co:Pi/CoOx/CP) by an in situ template assembly strategy followed by a fast microwave-induced plasma (MIP). The obtained three-dimensional (3D) Co:Pi/CoOx/CP exhibits an ordered honeycomb-like porous structure with superhydrophilicity, high surface area, and abundant surface defects, and is highly active for catalyzing the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). In situ Raman and ex situ spectroscopic and microscopic characterizations reveal a large number of surface defects and cobalt phosphate formation induced by MIP and elucidate their significant effects on the excellent catalytic performance of 3D Co:Pi/CoOx/CP.