Low-temperature synthesized Mo₂C and novel Mo₂C–MnO₂ heterostructure for highly efficient hydrogen evolution reaction and high-performance capacitors

Here, a facile and cost-effective way is proposed to synthesize Mo₂C nanoparticles and Mo₂C/MnO₂ heterostructures by utilizing laboratory waste. The Mo₂C nanoparticles are well encapsulated by graphitic carbon layers, which provide high cyclic and structural stability to Mo₂C. The electrochemical hydrogen evolution reaction (HER) activity and capacitive properties of these samples are studied in detail. Mo₂C synthesized at 500 °C exhibits higher HER activity with a Tafel slope of 79 mV dec⁻¹. To further improve the HER activity of Mo₂C nanoparticles, the heterostructure of Mo₂C and MnO₂ is developed. The optimized Mo₂C/MnO₂ (2:1) heterostructure delivers a current density of 10 mA cm⁻² at a low overpotential of 58.3 mV and shows a very low Tafel slope of 36 mV dec⁻¹. It exhibited long-term cyclic stability up to 5000 cyclic voltammetry (CV) cycles. This paper describes a novel and effective method for fabricating noble metal-free HER electrocatalysts utilizing laboratory waste as a carbon precursor.