Developing sustainable carbon materials from agricultural waste offers promising solutions to both energy-storage and water-treatment challenges. This study reports the synthesis of a nitrogen-doped Tondolo-derived activated carbon (N-TAC), an underexplored African wetland sedge whose fibrous morphology directs pore architecture. Rather than conventional dry mixing, K₂CO₃ and urea were co-dissolved and intimately blended with the finely reduced Tondolo precursor. This reagent-level homogeneity enabled a single pyrolysis at 700 °C in which carbonisation, chemical activation, and nitrogen doping proceeded concurrently. The N-TAC Near-surface nitrogen functionalities (pyridinic, pyrrolic, and graphitic) proved decisive in enhancing both electrochemical and adsorptive performance. Three-electrode characterization in 1 M NaNO₃ revealed coexisting EDLC and pseudocapacitive mechanisms, with a low ESR of 2.05 Ω and relaxation time constant of 0.87 s confirming rapid ion diffusion kinetics. Trasatti deconvolution and Dunn's method reveal that pyridinic and pyrrolic sites selectively amplify pseudocapacitive contributions (63–71%) in the positive potential window, a window-dependent asymmetry not previously reported for neutral-electrolyte biomass carbons. The assembled symmetric device delivered 12.1 Wh kg⁻¹ with 94% capacitance retention after 10 000 cycles. For water remediation, N-TAC achieved 99.9% methylene blue removal at 50 ppm with an adsorption capacity of 557.6 mg g⁻¹, governed by chemisorption via electrostatic and π–π interactions, best described by pseudo-second-order kinetics (R² = 0.97) and the Temkin isotherm (R² = 0.958). These results position N-TAC as a competitive sustainable material at the water–energy nexus, with future perspectives including binder-free electrode fabrication, electrochemical degradation coupling, and regenerable architectures for long-term sustainability.

Bioengineering of bimetallic oxides is a significant requirement for both social and environmental applications. In this work, bimetal oxide nanomaterials, Zinc orthotitanate Zn₂TiO₄ was produced using a green process which utilizes natural extract of Hibiscus sabdariffa. More accurately, natural extract/phyto-compounds of Hibiscus sabdariffa was validated as an effective chelating agent at room temperature and atmospheric pressure. A variety of techniques were applied to analyse their physicochemical properties and verify the production of the Zn₂TiO₄ nanoparticles. The XRD analysis illustrated the crystalline structure of the Zn₂TiO₄ nanocomposites. The SEM analysis showed the morphology of the compounds Zn₂TiO₄ to be highly porous. The EDS analysis validated the presence of elements such as Ti, and Zn while FTIR analysis indicated the existence of multiple functional groups, including O-H, C-H, C=O, Ti-O, and Zn-O bonds in the compound. The PL peaks identified at 240 and 450 nm are attributed to the charge transfer characteristics present in the surface state of the resulting product. The single phase crystals of the bio-engineered Zn₂TiO₄ were found to be within the nanoscale while exhibiting a significantly elevated photocatalytic efficacy in decomposing Methylene Blue reaching a threshold of about 94.1% efficacy at about 120 min. From the electrochemistry viewpoint, the bioengineered Zn₂TiO₄ nanomaterial demonstrated enhanced redox activity and stability, exhibiting 94.2% current retention after 20 cycles. Cyclic voltammetry (CV) studies confirmed a diffusion-controlled process, while electrochemical impedance spectroscopy (EIS) revealed a 10-fold reduction in charge transfer resistance ®_ct), from 5.48 to 0.53 KΩ. This significant acceleration in electron transfer kinetics is corroborated by a nearly 2-fold increase in interfacial admittance (Y_o), indicating an expanded electroactive surface area. These results demonstrate the applicability and potential for Zn₂TiO₄ nanomaterial in advanced electrochemical applications. From the antibacterial perspective, Zn₂TiO₄ nanomaterial showed limited activity in the agar-disc diffusion assay, with no meaningful inhibition against most tested Gram-positive and Gram-negative strains and only a marginal response against K. pneumoniae. These results suggest that any antibacterial potential of the Zn₂TiO₄ nanomaterial may likely to be strongly dependent on assay format, nanoparticle dispersion, contact conditions, and possible light-driven ROS generation.