Engineering of bifunctional nanocomposite with enhanced redox-type energy storage and oxygen evolution reaction performance

The development of advanced energy storage and conversion devices, including supercapacitors (SCs) and oxygen evolution reactions (OER), relies heavily on innovative and multifunctional electrode materials with outstanding electrochemical properties. Herein, we design a multi-architectured NiMoO₂/C@CoFe-CHH thin hexagonal nanosheet (HNS) structures electrode using a two-step thermal and hydrothermal approach for energy storage and electrocatalyst. The composite composed of unique thin HNS architecture on biomass-derived carbon which demonstrate an efficient, highly porous structure that facilitates ion diffusion, accelerates electron transfer, and enhances the number of active sites for NiMoO₂/C and CoFe-CHH HNS. When used a redox-type electrode, the composite NiMoO₂/C@CoFe-CHH HNS electrode exhibit a high specific capacitance of 1253F g^–1 at 0.5 A g^–1 with an excellent cycling performance of 98.65 % retention after 1,00,000 charge–discharge cycles. Furthermore, the NiMoO₂/C@CoFe-CHH HNS electrode showed remarkable cycle stability and with high rate capability, which are beneficial for proto-type energy storage applications. With the NiMoO₂/C@CoFe-CHH HNS electrode as a positive electrode and biomass derived activated carbon as a capacitive-type electrode, asymmetric SC was fabricated, which showed an ultra-high energy density of 80 Wh kg⁻¹ at 785 W kg⁻¹, which are beneficial for powering light-emitting diodes (LEDs). Additionally, the NiMoO₂/C@CoFe-CHH HNS electrode demonstrates excellent performance as an OER electrocatalyst, exhibiting a low overpotential of just 226 mV at a current density of 10 mA cm^–2. Moreover, the composite electrode maintains outstanding stability for over 50 h at a current density of 100 mA cm^–2. This study provides novel ideas on the fabrication of ultrathin CoFe-CHH HNS on porous NiMoO₂/C electrocatalysts for flexible energy conversion and storage devices.