Deliberate Amorphization of Co‐MOF for Constructing Crystalline‐Amorphous Heterostructures Toward High‐Performance Water Electrolysis

Abstract The endowment of metal organic frameworks (MOF) with superior electrocatalytic performance without compromising their structural/compositional superiorities is of great significance for the development of renewable energy devices, yet remains a grand challenge. Herein, a deliberate partial amorphization strategy is developed to construct a heterostructured electrocatalyst consisting of crystalline Co‐MOF and amorphous Co‐S nanoflake arrays aligned on the carbon cloth (CC) substrate (abbreviated as Co‐MOF/Co‐S@CC hereafter) through a rapid sulfuration method. The simultaneous implement of crystalline‐amorphous (c‐a) heterostructure and nanoflake arrayed architecture on CC substrate renders the Co‐MOF/Co‐S@CC with abundant and tight active sites, accelerated charge transfer rate, regulated electronic structures, and reinforced structural stability. As such, the obtained Co‐MOF/Co‐S@CC electrode demonstrates outstanding electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances with the overpotentials of 64 and 217 mV at 10 mA cm −2 , respectively. Moreover, a two‐electrode electrolyzer assembled by Co‐MOF/Co‐S@CC electrodes exhibits the lower cell voltages and larger current densities than those of Pt/C and RuO 2 counterparts, excellent reversibility and prominent long‐term stability, representing a great prospect for feasible H 2 production. This adopted concept of c‐a heterostructure for electronic regulation may bring about insightful inspiration for designing high‐performance electrocatalysts for sustainable energy systems.