Nitrogen-doped TiO₂ nanotube arrays (N-TNAs) were successfully fabricated by a simple thermal annealing process in ambient N₂ gas at 450 °C for 3 h. TNAs with modified morphologies were prepared by a two-step anodization using an aqueous NH₄F/ethylene glycol solution. The N-doping concentration (0–9.47 at %) can be varied by controlling N₂ gas flow rates between 0 and 500 cc/min during the annealing process. Photocatalytic performance of as-prepared TNAs and N-TNAs was studied by monitoring the methylene blue degradation under visible light (λ ≥ 400 nm) illumination at 120 mW·cm⁻². N-TNAs exhibited appreciably enhanced photocatalytic activity as compared to TNAs. The reaction rate constant for N-TNAs (9.47 at % N) reached 0.26 h⁻¹, which was a 125% improvement over that of TNAs (0.115 h⁻¹). The significant enhanced photocatalytic activity of N-TNAs over TNAs is attributed to the synergistic effects of (1) a reduced band gap associated with the introduction of N-doping states to serve as carrier reservoir, and (2) a reduced electron‒hole recombination rate.

In this study, we provide a simple and green approach to recycle waste zinc carbon batteries for making carbon dots and porous carbon material. The carbon dots are easily synthesized by one green step, the hydrothermal treatment of a carbon rod in a mixture of DI water and pure ethanol to obtain a blue fluorescence under UV light, which can be used directly as a fluorescence ink. The as-prepared carbon dot process give typical dots with a uniform diameter from 3 to 8 nm with a strong slight blue fluorescent. The porous carbon material is also recycled from carbon powder in a waste battery via one green step annealing process without any chemical activation and with a hierarchically porous structure. This porous carbon material is demonstrated as an electrode for symmetrical solid state supercapacitors (SSCs) in a sandwich structure: porous carbon/PVA–KOH/porous carbon. The SSCs using recycled porous carbon electrodes exhibit a good energy density of 4.58 W h kg⁻¹ at a power density of 375 W kg⁻¹ and 97.6% retention after 2000 cycles. The facile one green step of hydrothermal and also that of calcination provide a promising strategy to recycle waste zinc carbon batteries, which transfers the excellent applications.

The present work shows the process for MoS₂ nanosheet production by liquid N₂-queched bulk, a novel method having highly efficient, green, and facile operation. The produced MoS₂ nanoparticles are suspended in minimum quantity cooling lubrication (MQCL)-based fluid to form nanofluid used for the hard milling of AISI D2 steel. The study aims to improve the hard-milling performance assisted by the MQCL technique using MoS₂ nanofluid. ANOVA analysis is used to evaluate the effects of three input machining variables, including nanoparticle concentration, cutting speed, and material hardness on cutting forces. The results indicate that the better cooling effect from the principle of the Ranque–Hilsch vortex tube of the MQCL device combined with the better lubricating performance from MoS₂ nanofluid brings out the sustainable alternative solution for machining difficult-to-cut material. Moreover, the experimental results provide the technical guides for the selection of proper values of nanoparticle concentration and cutting speed while ensuring the technological, economic, and environmental characteristics.

In this report, the silver Nanoparticles (AgNPs)were successfully synthesized in a simple one-pot method by the leaf and stemextract of Disporopsis longifolia as reducing, capping agents, andstabilizers for the first time. The optimal extract amount, AgNO₃concentration, reaction temperature, and time for the AgNPs synthesis wereidentified using Ultraviolet-Visible (UV-Vis) spectroscopy. X-Ray Diffraction (XRD)and Scanning Electron Microscopy (SEM) were used to characterize the structureand morphology of the as-synthesized AgNPs. In addition, the characteristicvibration of the Ag-organic functional group was confirmed using Fourier TransformInfrared (FT-IR) spectroscopy. The as-synthesized AgNPs exhibited promising MethyleneBlue (MB) photodegradation, resulting in approximately 100% removal after 240min without any substantial silver leaching under the solar light. It is foundthat the AgNPs photocatalysis activity is improved by the synergy of the Disporopsislongifolia extract solution and can efficientlyadapt to the photodegradation of organic dyes in industrial wastewater.

A novel facile combination of precipitation and plasma discharge reaction is successfully employed for one-step synthesis of an α-Fe₂O₃–Fe₃O₄graphene nanocomposite (GFs).