MnO₂/Co₃O₄ with N and S co-doped graphene oxide bimetallic nanocomposite for hybrid supercapacitor and photosensor applications

This report presents the synthesis of MnO₂/Co₃O₄ with N and S co-doped graphene oxide (GO) hybrid composite by hydrothermal route for supercapacitor and photosensor applications. MnO₂/Co₃O₄ nanoflakes and nanoparticles were directly grown on dual N and S doped GO sheets, where doping was achieved using a single reagent thiourea in one-pot synthesis. Individual Co₃O₄ and MnO₂ electrodes have poor reversibility and cycling properties due to electrolytic instability and low electrical conductivities. However, the hybrid provides good catalytic properties, and combined with highly conducting two-dimensional GO it can reduce mismatching properties due to high conductivity and layered structure. The incorporated composite sheet-like structure provides good mechanical strength with high conductivity, permitting easy ion penetration into the electrode, and providing considerably more active surfaces. Thus, the proposed hybrid material delivers significantly improved performance for supercapacitor and/or photosensor applications, achieving 614 F.g⁻¹ specific capacitance at 1 Ag⁻¹, and exceeding 95% retention up to 10 000 cycles. This composite material also shows good photosensing with 1 order of increased current under visible light.