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Nitroaromatic compounds represent a class of highly toxic pollutants discharged into aquatic environments by various industrial activities, posing significant threats to ecological integrity and human health due to their persistent and hazardous nature. In this study, Pd-doped ZnO nanoparticles were investigated as a potential solution for the degradation of nitro organics, offering heightened photocatalytic efficacy and prolonged stability. The synthesis of Pd-doped ZnO NPs was achieved via the hydrothermal method, with subsequent analysis through XRD spectra and XPS confirming successful Pd doping within the ZnO matrix. Characterization through FESEM and HRTEM unveiled the heterogeneous morphologies of both undoped and Pd-doped ZnO nanoparticles. Additionally, UV–vis and PL spectroscopy provided insights into the optical properties, chemical bonding, and defect structures of the synthesized Pd-doped ZnO NPs. Pd doping induces a redshift in ZnO's absorption spectra, reducing the bandgap from 3.12 to 2.94 eV as Pd concentration rises from 0 to 0.2 wt.%. The photocatalytic degradation, following pseudo-first-order kinetics, achieved 90% nitrobenzene abatement (200 µg/L, pH 7) under visible light within 320 min with a catalyst loading of 16 µg/mL. The photocatalytic efficacy of 0.08 wt% Pd-doped ZnO (k = 0.058 min⁻1) exhibited a 25-fold enhancement compared to bare ZnO (k = 3.1 × 10–4 min-1). Subsequent quenching and ESR experiments identified hydroxyl radicals (OH•) as the predominant active species in the degradation mechanism. Mass spectrometry analysis unveiled potential breakdown intermediates, illuminating a plausible degradation pathway. The investigated Pd-doped ZnO nanoparticles demonstrated reusability for up to five successive treatment cycles, offering a sustainable solution to nitro organics contamination challenges. [ABSTRACT FROM AUTHOR]

The high concentration of nitrogen dioxide (NO2) gets it one of the most popular and harmful air pollutants. This work examines the NO2 gas sensing properties of palladium-doped zinc oxide (Pd-ZnO) nanorods. The Pd-ZnO nanorods were synthesized by chemical hydrothermal method with different Pd doping concentrations (0–1 wt%). The Pd-ZnO nanorods were characterized by XRD, FESEM, and XPS for their structural and morphological properties, respectively. The ZnO nanostructures show hexagonal structures, and XRD and XPS results confirmed the doping of Pd on ZnO nanostructures. The Pd (1 wt%)-ZnO nanorods-based sensor shows high response of 22.1 with response/recovery time of 67/118 s toward 100 ppm NO2, while it exhibits a response of 7 with response/recovery times of 80/145 s for 1 ppm NO2, at 200 °C. The sensor is observed very selective for NO2 compared to other gases like carbon monoxide (CO), ammonia (NH3), and hydrogen (H2). The sensor has strong stability for a longer time (35 days) in a dry and humid (RH 60%) environment. The mechanism of gas sensors is further explained by the Crowell-Sze model in Finite-Difference Time-Domain (FDTD) simulation using COMSOL Multiphysics using drift Diffusion-Poisson equations to simulate the electric potential distribution in the nanorods during the gas sensing. [ABSTRACT FROM AUTHOR]

Microbial pathogens are known for causing great environmental stress, owing to which emerging challenges like lack of eco-friendly remediation measures, development of drug-resistant and mutational microbial strains, etc., warrants novel and green routes as a stepping stone to serve such concerns sustainably. In the present study, palladium (Pd) doped manganese (II, III) oxide (Mn3O4) nanoparticles (NPs) were synthesized using an aqueous Syzygium aromaticum bud (ASAB) extract. Preliminary phytochemical analysis of ASAB extract indicates the presence of polyphenolics such as phenols, alkaloids, and flavonoids that can act as potential capping agents in NPs synthesis, which was later confirmed in FTIR analysis of pure and Pd-doped Mn3O4 NPs. XRD, Raman, and XPS analyses confirmed the Pd doping in Mn3O4 NPs. FESEM and HRTEM study reveals the mixed morphologies dominated by nanocorns appearance. Zeta potential investigation reveals high stability of the synthesized NPs in colloidal solutions. The developed Pd-doped Mn3O4 NPs were tested against two fungal phytopathogens, i.e., Sclerotinia sclerotiorum and Colletotrichum gloeosporioides, known for causing great economic losses in yield and quality of different plant species. The antifungal activity of synthesized Pd‐doped Mn3O4 NPs displayed a dose‐dependent response with a maximum of ~92%, and ~72% inhibition was recorded against S. sclerotiorum and C. gloeosporioides, respectively, at 1000 ppm concentration. However, C. gloeosporioides demonstrated higher sensitivity to Pd‐doped Mn3O4 NPs upto 500 ppm) treatment than S. sclerotiorum. The prepared NPs also showed significant antibacterial activity against Enterococcus faecalis. The Pd-doped Mn3O4 NPs were effective even at low treatment doses, i.e., 50–100 ppm, with the highest Zone of inhibition obtained at 1000 ppm concentration. Our findings provide a novel, eco-benign, and cost-effective approach for formulating a nanomaterial composition offering multifaceted utilities as an effective antimicrobial agent. [ABSTRACT FROM AUTHOR]

In the present work, hydrogen gas sensing properties of palladium-capped copper oxide (Pd/CuO) thin films have been investigated. The Pd/CuO thin films were deposited on glass substrate for different deposition times (10–30 min) using direct current magnetron sputtering. The Pd/CuO thin films were characterized by x-ray diffraction, field emission scanning electron microscopy, atomic force microscopy and x-ray photoelectron spectroscopy for their structural, morphological and compositional properties, respectively. The Pd/CuO thin film sensor deposited for 10 min presents a remarkable sensing performance with fast response/recovery time of 10 s/50 s for hydrogen gas at a concentration of (1000 ppm) and optimum operating temperature of 300°C. The sensor is observed to be highly selective towards hydrogen (H2) gas compared to the other gases such as carbon monoxide (CO) and ammonia (NH3). The sensor is stable under high humidity conditions (60% RH). The studied Pd/CuO thin film sensor can be used to design a simple and low-cost sensor to detect low concentrations of H2 gas for use in hydrogen-driven industries. [ABSTRACT FROM AUTHOR]