Controllable nanoarchitecture arrays of the transition metal selenide, supported on conductive substrates, are promising materials for high-performance electrochemical energy storage and conversion applications. Herein, Ni₃Se₂ nanowire arrays with a rich-grain-boundary are rationally grown on a nickel foam (NF) substrate by the solvothermal method. Under optimized conditions, the Ni₃Se₂ nanowire arrays prominently display high areal capacitance of 635 μA h cm⁻² at a current density of 3 mA cm⁻² and excellent rate capability. As an asymmetric supercapacitor, the Ni₃Se₂ electrode (cathode) shows a high energy density of 42.6 W h kg⁻¹ at a power density of 284.8 W kg⁻¹. When used as a two-dimensional (2D) electrode for water splitting reaction, the Ni₃Se₂ electrode exhibits high catalytic activity to achieve 100 mA cm⁻² at an overpotential of 320 mV in the oxygen evolution reaction and a low overpotential of 95 mV at a current density of 50 mA cm⁻² in the hydrogen evolution reaction in a 1.0 M KOH solution. The Ni₃Se₂ nanowire array electrode is shown to be a high-performance alkaline water electrolyzer with current density of 10 mA cm⁻² at a cell voltage of 1.62 V. The results demonstrate Ni₃Se₂ as a promising 2D highly active electrode for electrochemical energy storage and conversion applications.

The large-scale use of antibiotics is causing serious water pollution problems, and it is of great significance to develop new technologies to remove antibiotics from water. As an environmentally friendly and economical adsorption material, carbon derived from biomass is a low-cost and feasible material for removing antibiotics in sewage, but the current removal efficiencies are not high enough for large-scale practical application. In this study, poplar wood chips are used as raw material, and a magnetic biochar is prepared by co-pyrolysis of poplar wood chips and FeCl₃/CaCl₂ mixed molten salt. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N₂-isothermal adsorption and desorption, X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) techniques showed the successful synthesis of Fe₂O₃/bioC composite. In-situ formed Fe₂O₃ makes the biochar possess the characteristic of superparamagnetic, which is conducive to the recycling of biochar. Due to the etching effect of the molten salts, rough surface was formed on Fe₂O₃/bioC, resulting in a maximum norfloxacin (NOR) adsorption ability up to 38.77 mg g⁻¹ at pH 6.0. The NOR adsorption behavior on Fe₂O₃/bioC followed the pseudo second order kinetic model and the equilibrium data was best fitted the Langmuir model. In addition, the adsorption process of NOR on Fe₂O₃/bioC was thermodynamically spontaneous. The results show that this low-cost and reusable magnetic biochar has the potential for rapid and efficient removal of antibiotic from aqueous solution.