Herein, a facile green synthesis route was reported for the synthesis of Ag–ZnO nanocomposites using potato residue by simple and cost effective combustion route and investigated the photocatalytic degradation of methylene blue (MB) dye. In the preparation potato extract functioned as a biogenic reducing as well as stabilizing agent for the reduction of Ag + , thus eliminating the need for conventional reducing/stabilizing agents. Ag–ZnO nanocomposites with different Ag mass fractions ranging from 2 to 10% were characterized by using XRD, FT-IR, XPS, SEM, TEM, and UV–Vis spectroscopy. XRD analysis revealed that the as prepared Ag–ZnO nanocomposites possessed high crystallinity with hexagonal wurtzite structure. TEM and SEM images showed that the Ag–ZnO nanocomposites in size ranging from 15 to 25 nm have been obtained, and the particle size was found to increase with the increase in percentage of Ag. FTIR results confirmed the characteristics band of ZnO along with the Ag bands. XPS analysis revealed a pair of doublet with peaks corresponding to Ag and a singlet with peaks corresponding to ZnO. With the increase of concentration of Ag in ZnO, the intensity of NBE emission in the PL spectra was observed to be decrease, resulted to the high photocatalytic activity. Photocatalytic properties of Ag–ZnO nanocomposites evaluated against the MB dye under visible-light irradiation showed superior photodegradation of ~ 96% within 80 min for 2% Ag–ZnO nanocomposites. The apparent reaction rate constant for 2% Ag–ZnO nanocomposites was higher than that of other nanocomposites, which proved to be the best photocatalyst for the maximum degradation of MB. Furthermore, various functional parameters such as dosing, reaction medium, concentration variation were performed on it for better understanding. The enhancement in photocatalytic degradation might be due to the presence of Ag nanoparticles on the surface of ZnO by minimizing the recombination of photo induced charge carriers in the nanocomposites.

The construction of a UV-Vis and direct sunlight functioning photocatalyst is a puzzling task for organic pollutant removal.

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In this study, we report the fabrication of graphitic carbon nitride doped zinc oxide nanocomposites, g-C3N4/ZnO, (Zn-Us) by using different amount of urea. They were further characterized by X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Raman, UV-vis, Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM) techniques. The prepared nanocomposites were used as photocatalysts for the mineralization of the light sensitive dyes Methylene Blue (MB) and Rose Bengal (RB) under UV light irradiation, and corresponding photo-mechanism was proposed. Benefiting from these photocatalytic characteristics, urea derived g-C3N4/ZnO photocatalysts have been found to have excellent photodegradation activity against the MB and RB for 6 h and 4 h, respectively. Under the given experimental conditions, the degradation percentage of fabricated Zn-Us were shown ~90% for both model dyes. Compared to cationic MB dye, anionic RB dye is more actively degraded on the surface of prepared photocatalysts. The results obtained can be effectively used for future practical applications in wastewater treatment

In this work, NaOH-activated Aerva javanica leaf (NAJL) powder was successfully developed as a cost-effective adsorbent for removal of crystal violet (CV) from an aqueous environment. The prepared adsorbent was characterized using FTIR, SEM, and their surface area was determined by BET technique. Different parameters affecting the adsorption of CV dye such as pH solution, adsorbent dose, equilibrium time, initial CV concentration, and temperature were investigated. The results revealed that the best-optimized values were found as pH-9, dose-20 mg, time-30 min, temperature-25 °C . The adsorption experimental data exhibited excellently fitted well to the nonlinear Langmuir isotherm and Pseudo-first-order kinetic models. The maximum monolayer adsorption capacity of CV dye was 315.2 mg/g. The experimental parameters of thermodynamic analysis exhibited that the CV dye adsorption onto NAJL powder was exothermic and spontaneous. Electrostatic attraction, π-π interactions, and Hydrogen bonding were the mechanism behind the adsorption of CV dye.

In this study, we fabricated Zn3V2O8 and a Ag-modified Zn3V2O8 composite (Zn3V2O8/Ag) by utilizing effective and benign approaches. Further characterization techniques such as powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were explored to examine the phase and structural properties, respectively, of the synthesized Zn3V2O8/Ag and Zn3V2O8/Ag composite materials. The oxidation states and elemental composition of the synthesized Zn3V2O8/Ag and Zn3V2O8/Ag were characterized by adopting X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX). The optical band gaps of the synthesized Zn3V2O8/Ag and Zn3V2O8/Ag were examined by employing ultraviolet–visible (UV-vis) diffuse reflection spectroscopy. HRTEM images clearly show that ZnV@Ag NC has a hexagonal plate-like morphology. Subsequently, Zn3V2O8 and Zn3V2O8/Ag were used as photocatalysts for photocatalytic hydrogen (H2) production. It was observed that after Ag doping, the energy band gap of ZnV was reduced from 2.33 eV to 2.19 eV. EDX mapping images also show the presence of Ag, O, Zn, and V elements and confirm the formation of ZnV@Ag NC with good phase purity. Observations clearly showed the presence of excellent photocatalytic properties of the synthesized photocatalyst. The Zn3V2O8/Ag photocatalyst exhibited H2 generation of 37.52 µmolg−1h−1, which is higher compared to pristine Zn3V2O8. The Zn3V2O8/Ag photocatalyst also demonstrated excellent reusability, including decent stability. The reusability experiments suggested that ZnV@Ag NC has excellent cyclic stability for up to six cycles.

This study demonstrated the hydrothermal synthesis of bimetallic nickel-cobalt tungstate nanostructures, Ni-CoWO4 (NCW-NPs), and their phase structure, morphology, porosity, and optical properties were examined using X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), high resolution Transmission electron microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) and Raman instruments. It was found that as-calcined NCW-NPs have a monoclinic phase with crystal size ~50–60 nm and is mesoporous. It possessed smooth, spherical, and cubic shape microstructures with defined fringe distance (~0.342 nm). The photocatalytic degradation of methylene blue (MB) and rose bengal (RB) dye in the presence of NCW-NPs was evaluated, and about 49.85% of MB in 150 min and 92.28% of RB in 90 min degraded under visible light. In addition, based on the scavenger’s study, the mechanism for photocatalytic reactions is proposed.

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