The development of high-performance photocatalysts is vital for combating water pollution and microbial contamination. In this study, visible-light-active Z-scheme heterojunction nanocomposites composed of Co₃O₄ and Nb₂O₅ (CNNC) were synthesized via co-crystallization and subsequent high-pressure annealing to enhance photocatalytic and antimicrobial performance. Structural and optical analyses via XRD, FESEM, TEM, XPS, and PL confirmed the heterojunction formation between porous Co₃O₄ nanoparticles (CONP) and columnar orthorhombic Nb₂O₅ nanoparticles (NONP). The CNNC exhibited significantly improved photocatalytic activity, achieving degradation efficiencies of 95.1% for methylene blue, 72.6% for tetracycline, and 90.0% for Congo red within 150 min. Kinetic studies showed that CNNC’s rate constants were 367% and 466% of those of CONP and NONP, respectively. Moreover, CNNC demonstrated a strong antibacterial effect on Staphylococcus aureus and Escherichia coli with ZOI values of 9.3 mm and 6.8 mm, respectively. Mechanistic analysis revealed that the Z-scheme charge-transfer pathway improved charge separation and reduced electron–hole recombination, contributing to the promoted photocatalytic efficiency. The nanocomposite also showed robust stability and recyclability over five times. These results highlight the promise of CNNC as a bifunctional, visible-light-driven photocatalyst for pollutant decomposition and microbial control.

In this study, copper oxide nanoparticles (CuO NPs), zinc oxide nanoparticles (ZnO NPs), and copper oxide/zinc oxide nanocomposites (CuO@ZnO NPs) were synthesized by green synthetic route where bioactive compounds inherently present in the leaf extract of Artemisia vulgaris act as stabilizing and reducing agents. Phytochemicals present in leaf extract were assessed by qualitative chemical tests and spectroscopic measurements. UV-visible spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Energy Dispersive X-ray (EDX) spectroscopy, X-ray Diffraction (XRD), and Field Emission Scanning Electron Microscopy (FESEM) were used to characterize the as-synthesized nanomaterials, i.e., CuO, ZnO, and CuO@ZnO NPs. XRD pattern revealed the crystalline nature of nanoparticles. Based on the DebyeScherrer formula, the sizes of CuO NPs, ZnO NPs, and CuO@ZnO NCs were found to be 17.24, 20.74, and 22.50nm, respectively. The band gap of the as-prepared nanomaterials was measured using the Tauc plot. Using the nanomaterials, MB degradation was studied at room temperature under exposure to UV light. The degradation efficiency of CuO, ZnO, and 2 CuO@ZnO was found to be 52, 68, and 98, respectively. Kinetic degradation process reveals that the CuO@ZnO NCs showed a better photocatalytic activity on MB dye with the degradation constant of 0.04124min⁻¹ compared to those of either constituent. Based on the findings, it was found that CuO@ZnO nanocomposites have the potential to degrade MB as an organic dye and can be used for wastewater treatment.

Efficient photocatalysts based on composite materials are essential for addressing environmental pollution and enhancing water purification. This study presents a novel BiOI/V₂O₅ nanocomposite (BVNC) with a flower-like layered structure, synthesized via a low-temperature solvothermal process followed by high-pressure annealing for visible light (VL)-driven dye degradation and antibacterial activities. Compared to individual BiOI nanoparticles (BOINP) and V₂O₅ nanoparticles (VONP), under VL, the BVNC demonstrated significantly enhanced photocatalytic and antibacterial activity. The best-performing BVNC achieved a remarkable methylene blue degradation efficiency of 95.7% within 140 min, with a rate constant value 439% and 430% of those of BOINP and VONP, respectively. Additionally, BVNC exhibited high photocatalytic efficiencies for rhodamine 6G (94.0%), methyl orange (90.4%), and bisphenol A (69.5%) over 160 min, highlighting the superior performance of the composite materials for cationic and anionic dyes. Furthermore, BVNC established outstanding antibacterial capability against Staphylococcus aureus and Escherichia coli, demonstrating zones of inhibition of 12.24 and 11.62 mm, respectively. The improved catalytic and antibacterial capability is ascribed to the presence of a robust p-n heterojunction between BOINP and VONP, which broadens the photo-absorption range, reduces bandgap energy, and facilitates the significant separation of excitons and faster release of reactive oxygen species.

Rational selection of active biomolecules in the synthesis of nanoparticles for reducing the precursor and functionalizing the nanoparticles (NPs) can offer remarkable comeback of biocompatibility and biological applicability. This work aimed at the synthesis of a cost-effective, ecofriendly, and a facile approach of silver nanoparticles (AgNPs) using methanolic leaf extract of Artemisia vulgaris. The phytochemical constituents present in the methanolic extract were characterized by qualitative chemical tests and spectroscopic measurements and employed for the reduction of silver nitrate into silver nanoparticles. Formation of AgNPs was monitored by UV-visible spectroscopic measurement. Fourier transform infrared (FTIR) spectroscopy reflected the presence of characteristic functional groups associated with the phytochemical constituents involved in the formation of nanoparticles. The crystalline phase and morphology of the NPs were assessed form X-ray diffraction (XRD) spectra and field emission scanning electron microscopy (FESEM), respectively. XRD pattern revealed the crystalline nature of nanoparticles with grain size of ∼ 28 nm based on the Debye Scherer formula. Study of antimicrobial activity of AgNPs against Gram-positive bacteria Bacillus subtili, Gram-negative bacteria Escherichia coli, and fungus Candida albicans exhibited good potential to control the bacterial and fungal growth.

For sustainable hydrogen production through water splitting, the rational engineering of economical and effective electrocatalysts/nanomaterials for the hydrogen evolution reaction (HER) is essential. In this work, we describe the logical design and in-situ development of a nickel-doped cerium metal-organic framework (Ni/Ce-BTC@NF) directly on 3D nickel foam (NF), designing a binder-free (freestanding) electrode with a distinctive three-dimensional (3D) nanopillar-like structure. The unique design of a crystalline Ce-BTC framework with evenly dispersed nickel while maintaining the intrinsic rod-like shape upon doping is confirmed by structural and morphological investigations. Electrochemical measurements reveal that Ni doping significantly enhances HER activity in alkaline medium, with Ni/Ce-BTC@NF achieving overpotentials of 108.9 mV and 196.1 mV to sustain 10 mA cm⁻² and 50 mA cm-2, respectively, outperforming pristine Ce-BTC@NF. Excellent durability is demonstrated by the material’s steady activity throughout a 24-hour time of continuous operation. The Ni/Ce-BTC@NF (−) // RuO2@NF (+) electrolysis configuration exhibits competitive total water-splitting performance requiring 1.67 V (cell voltage) at 10 mA cm-2. This research offers a viable method for designing cerium MOFs-based electrocatalysts with hierarchical topologies and modulated electronic structures for effective hydrogen generation.