Facile synthesis of novel Cu2NiBiX4 (X = Se, S) chalcogenides as bifunctional electrocatalysts for oxygen evolution reaction (OER) and supercapacitive performance†

There is a high requirement for very efficient catalytically active materials to produce and store sustainable fuels to fulfill global energy demand, and the design of cost-effective multifunctional electrocatalysts for the oxygen evolution reaction (OER) and supercapacitors has become prominent. Herein, quaternary chalcogenides of Cu₂NiBiS₄ and Cu₂NiBiSe₄ have been fabricated by a facile solvothermal method and applied for electrocatalytic OER and supercapacitance performance. Material characterization was undertaken with X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX), and UV-visible spectroscopy. The Cu₂NiBiSe₄ catalyst shows a low overpotential of 175 at 10 mA cm⁻² current density and a low Tafel slope of 61 mV dec⁻¹ for the OER. Whereas the Cu₂NiBiS₄ electrocatalyst retains an overpotential of 212 mV and Tafel slope of 78 mV dec⁻¹ for the OER at 10 mA cm⁻². A long-term durability test of Cu₂NiBiSe₄ for 12 h at 10 mA cm⁻² current density suggests that it may be a suitable substitute for noble-metal-based electrocatalysts for the oxidation of water in alkaline media. Moreover, Cu₂NiBiSe₄ delivers boosted supercapacitive behavior with an exceptional specific capacity of 1443 F g⁻¹ at 2.5 A g⁻¹ compared to Cu₂NiBiS₄ (1221 F g⁻¹ at 2.5 A g⁻¹). Furthermore, Cu₂NiBiSe₄ exhibits an admirable energy density of 24.3 W h kg⁻¹ at a power density of 450.7 W kg⁻¹ together with 98% retention after 100 cycles.