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

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 RuO₂ counterparts, excellent reversibility and prominent long-term stability, representing a great prospect for feasible H₂ 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.