The development of multifunctional nanostructured catalysts with high electrochemical activity and stability is crucial for sustainable technologies. Herein, we report the synthesis of CTAB-capped NiCo₂O₄ (CNC) spinel nanostructures via a facile co-precipitation method, engineered to enhance surface activity and charge transport. The optical and structural properties of the nanocomposite were confirmed by UV-Vis and TEM analysis, and the functional group present in the composite was confirmed by FT-IR study. The cubic spinel phase of the CNC was confirmed by XRD analysis. The band gap value was determined to be 2.15 eV, which confirmed the semiconductor nature of the nanocomposite. The photocatalytic degradation efficiency was achieved up to approximately 97% against malachite green. Additionally, CNC demonstrated excellent electrocatalytic performance in non-enzymatic glucose detection, exhibiting high sensitivity and reproducibility across a broad concentration range. Hence, the CNC acted as a potent oxidant for photoelectrochemical reactions.

Carbon nanostructured materials, such as nanosheets, can be synthetically produced from various natural waste sources through carbonization and activation. Potassium hydroxide (KOH) is a well-known agent for creating porous structures and refining the micro or nanostructure of carbon. This study explores the effect of KOH, in both its solute and solid forms, on the production of carbon from groundnut shells. Using KOH activation and thermal treatment, carbon nanosheets were synthesized from groundnut shells. The surface microstructure and individual carbon nanosheets showed significant changes when treated with solute KOH compared to solid KOH. This highlights that treatment with solute KOH is an efficient and cost-effective method for carbon nanosheet production. A column study revealed that using groundnut shell carbon nanosheets (GSCNS) to treat sewage wastewater resulted in a reduction in BOD from 393 mg L-1 to 112.23 mg L-1 (71.5%) and COD from 512.70 mg L-1 to 125 mg L-1 (75.6%). Additionally, GSCN treatment led to a 40-60% reduction in the cations and anions in sewage wastewater. This study emphasizes the effective utilization of groundnut shell-derived carbon nanosheets as an eco-friendly and cost-effective solution for wastewater treatment, addressing the environmental challenges of untreated sewage discharge in underdeveloped and developing regions.

The growing demand for clean and safe water has intensified research on advanced materials capable of addressing complex wastewater contaminants. Graphene and its functionalised nano-derivatives have emerged as versatile materials in water purification due to their exceptional physicochemical properties, including high surface area, tunable surface chemistry, superior mechanical strength and excellent electronic conductivity. The high surface area, mechanical strength and chemical stability of graphene-based materials enhance their adsorption capacity and effectiveness in removing heavy metals and trapping organic contaminants, such as pharmaceuticals and benzene-related chemicals, from wastewater. The π-π stacking, electrostatic interactions and surface functional groups play critical roles in promoting adsorption processes and enhancing the efficacy of graphene-based materials for contaminant removal from wastewater streams. This review summarises recent advancements in the use of graphene and its derivatives for wastewater treatment, providing insights into the underlying mechanisms governing contaminant removal and the potential of these nanocarbon materials for global water pollution mitigation.