Polycrystalline CoP/CoP₂ Structures for Efficient Full Water Splitting

Transition‐metal phosphides (TMPs) have attracted extensive attention for use in the field of full water splitting. Various methods have been investigated to obtain high catalytic activity, but in these synthetic processes other active materials are inevitably introduced to modify or load onto the surface of the TMP to further improve the catalytic performance. Herein, we describe a novel approach for preparing CoP/CoP 2 structures (650 °C) by pyrolysis of a complex formed from Co ions crosslinked with phytic acid (PA) using 2‐methylimidazole (MeIM). The integration of CoP 2 and CoP in the structures can enhance the intrinsic electrical conductivity, and facilitate electron transfer from solution to the electrode. Overpotentials of only 250 and 239 mV were required to support the current densities of 10 and 20 mA cm −2 for the oxygen evolution reaction and hydrogen evolution reaction, respectively, demonstrating the potential of the novel material for practical overall water splitting.