Honeycomb polypore biomass-derived activated porous carbon nanosheets/graphite/nafion composite: Green and sensitive electrocatalyst for nanomolar detection of Hg2+ ions and water-splitting reactions

The electrochemical strategies with green electrocatalysts propose a selective, steady, and sensitive direction for the trace analytes sensing, hydrogen evolution reaction (HER), and oxygen evolution reaction (OER) applications. Herein, Honeycomb Polypore biomass waste-derived NaOH-activated porous nanocarbon material was synthesized, which performs as a multifunctional electrocatalyst for Hg2+ sensing and water-splitting reactions with the support of graphite and Nafion composite. The optimized nanocomposite shows high electrochemical activity for the redox reaction of Hg2+ in 0.1 M phosphate-buffered saline of 5.0 pH with a lower limit of detection value of 2.309 nM, good stability, reproducibility, and anti-interference activity. For water-splitting reactions, the optimized nanocomposite shows better overpotential values of 0.447 V (HER in 0.5 M H2SO4) and 0.305 V (OER in 0.5 M KOH) at 10.0 mA/cm2 of current density. Also, the lower Tafel slope values of 0.089 V/decade and 0.075 V/decade of the optimum electrocatalyst signify superior proficiency towards the HER and OER activities, respectively. These outcomes validate the materials’ excellent multifunctional activity for Hg2+ detection in different water samples and water-splitting reactions, boosting their potential for environmental safety and energy production. [Display omitted] •Honeycomb Polypore biomass-derived carbon material was synthesised by green method.•NaOH-HPBWPCNSs was used as multi-use tool for Hg2+ sensing, HER, and OER.•Optimum sensor shows high electrochemical activity for Hg2+ as compared to bare-sensors.•NaOH-HPBWPCNSs/GT/NFCE serves low LOD (2.309 nM) and fine recovery in water samples.•Optimal catalyst shows lower Tafel slope and overpotential values towards HER and OER.