The enhanced catalytic performance of the self-supported CoxB-[0.2]P-O electrodes is characterized by a very low overpotential of 33 mV (Fig. B, Fig. ) at the standard geometric current density (η@ 10 mA cm -2 ). It shows outstanding electrocatalytic performance compared to reported self-supported cobalt-based catalysts (e.g. cobalt-boride-phosphide, cobalt phosphide spheres/cobalt hydroxide nanosheets, cobalt phosphide, cobalt boride, cobalt hydroxide, and cobalt pyrophosphate, cobalt oxide, and other cobalt catalysts ) for HER in alkaline solution to achieve η@ = 10 mA cm -2 (Fig. ). The control sample (Co(OH)2) and the NF substrate required relatively similar values (208 mV for Co(OH)2 and 306 mV for NF at η@ = 10 mA cm -2 ) as previously reported ones of 228 mV and 182 mV for Co(OH)2, and 252 mV for NF, respectively (Table ).