Amorphous/crystalline nanostructured Co–FeOOH/CoCe-MOF/NF heterojunctions for efficient electrocatalytic overall water splitting†

Hydrogen production by electrocatalytic water splitting is considered to be an effective and environmental method, and the design of an electrocatalyst with high efficiency, low cost, and multifunction is of great importance. Herein, we developed a amorphous Co–FeOOH/crystalline CoCe-MOF heterostructure (defined as Co–FeOOH/CoCe-MOF/NF) though a convenient cathodic electrodeposition strategy as a high-efficiency bifunctional electrocatalyst for water electrolysis. The Co–FeOOH/CoCe-MOF/NF nanocrystals provide remarkable electronic conductivity and plenty of active sites, and the crystalline/amorphous heterostructure with generates synergistic effects, providing plentiful active sites and efficient charge/mass transfer. Benefiting from this, the designed Co–FeOOH/CoCe-MOF/NF displays ultralow overpotentials of 226 and 74 mV to achieve 10 mA cm⁻² for oxygen evolution reaction and hydrogen evolution reaction, and also shows the superior performance for overall water splitting with a low voltage of 1.55 V at 10 mA cm⁻² in 1 M KOH. The work reveals a design of superior activity, cost-effective and multifunctional electrocatalysts for water splitting.