An efficient and sustainable gas diffusible OER anode toward industrial alkaline water-splitting is fabricated by simply immersing Ni foam in ethanolic FeCl ₃ etchant, which produces a microporous Ni backbone decorated with nanocatalysts.

A high activity of a two-dimensional (2D) copper oxide (CuO) electrocatalyst for the oxygen evolution reaction (OER) is presented. The CuO electrode self-assembles on a stainless steel substrate via chemical bath deposition at 80 °C in a mixed solution of CuSO₄ and NH₄OH, followed by air annealing treatment, and shows a 2D nanosheet bundle-type morphology. The OER performance is studied in a 1 M KOH solution. The OER starts to occur at about 1.48 V versus the RHE (η = 250 mV) with a Tafel slope of 59 mV dec⁻¹ in a 1 M KOH solution. The overpotential (η) of 350 mV at 10 mA cm⁻² is among the lowest compared with other copper-based materials. The catalyst can deliver a stable current density of >10 mA cm⁻² for more than 10 hours. This superior OER activity is due to its adequately exposed OER-favorable 2D morphology and the optimized electronic properties resulting from the thermal treatment.

This work reports on the concurrent electrochemical energy storage and conversion characteristics of granular copper oxide electrode films prepared using reactive radio-frequency magnetron sputtering at room temperature under different oxygen environments. The obtained films are characterized in terms of their structural, morphological, and compositional properties. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscope studies reveal that granular, single-phase Cu₂O and CuO can be obtained by controlling the oxygen flow rate. The electrochemical energy storage properties of the films are investigated by carrying out cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy tests. The electrochemical analysis reveals that the Cu₂O and CuO electrodes have high specific capacitances of 215 and 272 F/g in 6 M KOH solution with a capacity retention of about 80% and 85% after 3000 cycles, respectively. Cyclic voltammetry and chronoamperometry are used to study the electrochemical energy conversion properties of the films via methanol electro-oxidation. The results show that the Cu₂O and CuO electrodes are electro-catalytically active and highly stable.

Zn-doping populates the catalytically active Ni ³⁺ -OOH sites, and subsequently prevents the detrimental competition between the UOR and OER. Consequently, Zn@Ni-MOF demonstrates an outstanding ultra-high UOR current density.