NiCoP nanorod arrays as high-performance bifunctional electrocatalyst for overall water splitting at high current densities

The main energy consumption of industrial water electrolysis is electric energy, which accounts for ca . 80% of the total cost of water electrolysis . Developing highly efficient bifunctional electrocatalyst for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is essential to reduce the energy consumption. Herein, nickel foam (NF)-supported NiCoP nanorod array catalyst is prepared and used for HER and OER. Not only at a small current density (10 mA/cm 2 ), but also at the commercially required high current density (≥500 mA/cm 2 ), NiCoP/NF catalyst shows excellent bifunctional properties with extremely low overpotential and high stability. Small overpotentials of 60 and 253 mV are needed to drive the current density of 10 mA/cm 2 for HER and OER, respectively, and the cell voltage of overall water splitting is only 1.55 V. At the high current density of 500 mA/cm 2 , the overpotentials are 180 and 365 mV, and the corresponding cell voltage is only 1.83 V. Furthermore, the cell voltage hardly changes within 24 h of overall water splitting test, which makes the catalyst have promising applications in the industrial water electrolysis. The high performance of NiCoP/NF outperforms the commercial RuO 2 -Pt/C couple and most of the bifunctional Ni/Co-based catalysts reported so far.