Multi-metal interaction boosts reconstructed FeCoCrCuOx@CF toward efficient alkaline water electrolysis under large current density

The dynamic process of dissolution and redeposition of the Cr element greatly enhances the HER performance of the material. [Display omitted] •FeCoCrCuOx@CF exhibited a low overpotential of 40 mV at 10 mA cm−2 for HER.•The activity strongly depends on the process of Cr ion leaching and redeposition.•FeCoCrCuOx@CF worked high-stably at 500 mA cm−2 even in 6 M KOH, under 60 °C. Electrolysis of water is one of most promising technologies for green hydrogen production. However, the green hydrogen has a market of 4 % only, as the key-component for the technology, electrocatalyst, is expensive, inefficient or unstable. Herein, we design a series of multi-metal oxides (FeCoOx@CF, FeCoCrOx@CF, FeCoCuOx@CF, and FeCoCrCuOx@CF) on cobalt foams to achieve the high efficiency, low cost, and long-term stability by a simple thermal decomposition and electrochemical activation. Among them, FeCoCrCuOx@CF shows remarkable catalytic activity with an ultra-low overpotential (40 mV at 10 mA cm−2) and Tafel slope (27.3 mV dec−1) for hydrogen evolution reaction (HER), which is superior to most reported transition-metal catalysts and comparable to commercial Pt/C, because of the synergistic effect of multiple metals and strong Cr-OH interaction on the reconstructed surface as induced by the dynamic dissolution and redeposition process in the reaction. In addition, the catalyst shows excellent long-term stabilities for HER and overall water splitting at 500 mA cm−2. Importantly, FeCoCrCuOx@CF has the excellent activity and high stability (100 h with only 2 % increment in applied voltage) in the industrial working environment (6 M KOH, ∼ 60 °C). Most importantly, only 3.18 V is needed to obtain > 30 A on a large size electrode for AWE (16.5 cm2, ∼ 1.84 A cm−2) in the industrial conditions. Our findings should provide novel strategies for the design of efficient and stable catalysts toward industrial water electrolysis.