Co/CoP Heterojunction on Hierarchically Ordered Porous Carbon as a Highly Efficient Electrocatalyst for Hydrogen and Oxygen Evolution
Wei Li, Jing Liu, Peifang Guo, Haozhe Li, Ben Fei, Yanhui Guo, Hongge Pan, Dalin Sun, Fang Fang, Renbing Wu
Abstract
Abstract Designing non‐precious electrocatalysts to synergistically achieve a facilitated mass/electron transfer and exposure of abundant active sites is highly desired but remains a significant challenge. Herein, a composite electrocatalyst consisting of highly dispersed Co/CoP heterojunction embedded within a hierarchically ordered macroporous‐mesoporous‐microporous carbon matrix (Co/CoP@HOMC) is rationally designed through the pyrolysis of polystyrene sphere‐templated zeolite imidazolate framework‐67 (ZIF‐67) assemblies. The combined experimental and theoretical calculations reveal that Co/CoP interfaces not only provide richly exposed active sites but also optimize hydrogen/water absorption free energy via electronic coupling, while the interconnected macroporous structure enables a superior mass transfer to all accessible active sites. As a result, the as‐developed Co/CoP@HOMC composites exhibit outstanding catalytic activity with overpotentials of only 120 and 260 mV at 10 mA cm −2 for the hydrogen evolution reaction and oxygen evolution reaction in 1.0 m KOH, respectively. Moreover, an alkaline electrolyzer constructed by Co/CoP@HOMC requires an ultralow cell voltage of 1.54 V to achieve 10 mA cm −2 , outperforming that of the Pt@C||IrO 2 @C couple (1.64 V).