Electrochemical behavior of biochar, molybdenum trioxide and graphene nanocomposite for supercapacitors

• Synthesized MoO 3 /MLG/biochar (MGB 2) composites using hydrothermal technique. • MLG improves the conductivity and provide structural support to redox-active MoO 3 . • The porous biochar increases the surface area and lowers overall composite cost. • MGB 2 composite showed highest Csp of 367.8 F g -1 at 1 mVs -1 in the CV analysis. • In GCD analysis, MGB 2 exhibited the highest Csp of 385 F g -1 at 1 A g -1 . • MGB 2 delivered 16.17 Wh kg⁻¹ energy density at 1 A g⁻¹. In this research study, we report the preparation of coconut husk-based nanocomposites containing molybdenum trioxide (MoO 3 ), and multilayer graphene (MLG), using a one-pot hydrothermal technique. The ternary composite, having an optimized composition of MoO 3 , MLG, and biochar (80:10:10), exhibited a layered and porous morphology with MoO 3 nanoparticles homogenously distributed inside the layered graphene and biochar matrix. XRD analysis confirmed the formation of orthorhombic MoO 3 nanoparticles and a carbonaceous framework. The composite material was characterized by FTIR and XPS to verify its composition and chemical states. BET study further confirmed the porous surface of the nanocomposite due to the addition of coconut husk-based biochar. Surface morphology was analyzed using FESEM, and EDX results indicated the presence of Mo, O, and C in the material. Electrochemical characterization revealed a specific capacitance (C SP ) of 385.06 F g⁻¹ at 1 A g⁻¹ for the above-mentioned composite labeled as MGB 2. Moreover, CV analysis demonstrated a diffusion-type charge storage behavior of MGB 2 composite with improved rate capability, which is associated with the synergistic interaction of pseudocapacitive MoO 3 with highly conductive MLG and porous biochar. The prepared asymmetric supercapacitor device exhibited an energy density of 46.65 Wh kg -1 with a power density of 795 W kg -1 at 1 A g -1 . The device delivered 91.27% of capacitance retention after 7000 cycles. This research sheds light on the potential of using low-cost biomass-based biochar, graphene, and MoO 3 for a scalable and high-performance electrode material for supercapacitor applications.