N-doped porous carbon-supported CoxPy/NixPy catalyst with enhanced catalytic activity for hydrogen evolution reaction in alkaline solution and neutral seawater

Achieving an efficient electrochemical hydrogen evolution reaction (HER) implies continuous development of new electrocatalysts for reducing the electrolytic energy consumption with the improvement of the stability and economical preparation in commercial applications. In this article, a binary transition-metal (Co/Ni) phosphide incorporated with an N-doped porous carbon (NPC) carrier was synthesized via a homogeneous polymerization followed by a high-temperature carbonizing and phosphating process, which was characterized by various techniques such as XRD, XPS, SEM, and EDS. The binary metal-based phosphide material (CoxPy/NixPy-NPC) exhibits high efficient catalytic activity for HER with low overpotential of 126 mV and 203 mV at 10 mA mg−1 in 1.0 M KOH and seawater with KOH added, respectively. Also, it exhibits satisfactory stability for a 10 h continuous test in the alkaline electrolyte. Furthermore, CoxPy/NixPy-NPC has good HER performance in natural seawater electrolyte with a potential difference of 110 mV (based on Pt/C at 10 mA mg−1), which is superior or close to that of other metal phosphides reported in literature. The excellent catalytic performance can be attributed to the synergistic effects of CoxPy and NixPy nanoparticles, protecting the effect of NPC to CoxPy and NixPy from aggregation. This work may provide an economic and convenient method to produce carbon-supported bimetallic phosphides as electrocatalytic materials.