Encapsulation of cobalt prussian blue analogue-derived ultra-small CoP nanoparticles in electrospun N-doped porous carbon nanofibers as an efficient bifunctional electrocatalyst for water splitting

Transition metal phosphides have been considered as prospective bifunctional electrocatalysts for overall water splitting due to high activity and excellent stability. In this work, we report a facile strategy for synthesizing high-dispersion cobalt Prussian blue analogue-derived CoP nanoparticles that are decorated on N-doped electrospun porous carbon nanofibers (denoted as CoP@CNF). The CoP@CNF is obtained using electrospinning, subsequent carbonization, and phosphatization treatment. Due to the high conductivity, abundance of electrocatalytic active sites, and the synergistic effect between ultra-fine CoP nanoparticles and porous N-doped electrospun carbon nanofibers, the prepared CoP@CNF catalyst exhibits remarkable activity with low overpotentials (127 and 300 mV) at 10 mA cm−2, and small Tafel slopes (73.4 and 73.8 mV dec−1) for hydrogen evolution reaction and oxygen evolution reaction in alkaline electrolyte, respectively. A water electrolyzer cell fabricated by applying CoP@CNF as both anode and cathode catalysts needs 1.64 V to achieve 10 mA cm−2, and exhibits remarkably long-term stability. This work provides useful guidance for the preparation of bifunctional nanocomposite electrocatalysts and further extends the application of Prussian blue analogues in the field of energy conversion.