Ternary nanocomposite ReMIL-CN (ReSe2@MIL-53(Fe)@g-C3N4) for energy storage and electroactive integrated H2O2 sensor application.

Integrated electrochemical systems capable of simultaneous charge storage and biochemical sensing response have gained prominence in modern materials science and biomedical engineering by offering multifunctionality for next-generation smart devices. The present comprehensive study is focused on the synthesis and characterization of a ternary nanocomposite material, focusing on its applications in integrated electrode systems for BHSCs and hydrogen peroxide (H2O2) sensing. The synthesized ReMIL-CN (ReSe2@MIL-53(Fe)@g-C3N4) nanocomposite exhibits an average crystallite size of 27.27 nm, a specific surface area of 154 m2 g-1, and a specific pore volume of 0.022 cm3 g-1. The ReMIL-CN electrode offers maximum specific capacities (Q s) of 1925.5 C g-1 in a three-electrode testing setup and 423 C g-1 in a ReMIL-CN//AC full-cell setup. The values of the oxidation and reduction diffusion coefficients (D oxidation and D reduction) of the ReMIL-CN compound are 4.59 × 10-8 m2 s-1 and 1.45 × 10-8 m2 s-1, respectively. The highest obtained values of the energy density (E d) and power density (P d) are 50 Wh kg-1 and 2060 W kg-1, respectively. The ReMIL-CN//AC hybrid device demonstrates high stability response, with 95% capacity retention, 90% columbic efficiency, and 90% and 84% charge-discharge time retention over a prolonged period of 10 000 repeated cycles. The measured b-values of 0.59, 0.68, and 0.70 suggest the hybrid-natured operational mechanism of the ReMIL-CN//AC device. Moreover, the present composite-based electrode exhibits a sensitivity of S = 0.185 μA μM-1 cm2 with a linear operational range of 50-1000 μM for the H2O2 detection system. The device maintains 95% signal stability after 1000 cycles, with an LOD of 0.1 μM, a linear regression value of R 2 = 0.998, and a minimal response time of less than 3 seconds, demonstrating the excellent selectivity of the device. The outstanding electrochemical charge storage and sensing capabilities of this ternary nanomaterial enable its integration into real-time, self-powered bioelectrochemical monitoring for next-generation portable and wearable bioelectronics.