Hollow Bimetallic Cobalt-Based Selenide Polyhedrons for Efficient Hydrogen Production in Practical PEM Electrolysis

The development of efficient, stable, and cost-effective electrocatalysts for hydrogen evolution reactions is of utmost importance in order to replace expensive Pt-based catalysts in proton exchange membranes (PEMs) and advance the storage and conversion of hydrogen energy. Herein, a novel electrocatalyst, NixCo1–xSe2 N-doped carbon hollow polyhedrons (NCHP), was prepared by employing a ZIF-8@67 core–shell composite precursor and implementing a pyrolysis–selenylation process. In particular, Ni0.1Co0.9Se2/NCHP demonstrated a remarkable performance for the HER in a wide pH range. It exhibited a low overpotential of 89.8 mV and a small Tafel slope of only 48.3 mV dec–1 at a current density of 10 mA cm–2 in 0.5 M H2SO4. It could also exhibit exceptional properties in 0.1 M PBS and 1.0 M KOH conditions simultaneously. The PEM electrolyzer, incorporating Ni0.1Co0.9Se2/NCHP as the cathode, exhibited remarkably high critical current density (1.83 V@500 mA cm–2) and outstanding stability (500 mA cm–2@100 h). The microscopic characterization and theoretical calculation revealed that the evaporation of inner zinc effectively mitigated element agglomeration, while the incorporation of an appropriate amount of nickel atoms into CoSe2 induced favorable adsorption–desorption behavior. This modification accelerated the kinetics of the HER, thereby enhancing the electrocatalyst's intrinsic catalytic activity and stability.