A simple approach to synthesizing tin selenide nanostructures showing superior photocatalytic performance with variable tin ratios via a facile chemical method is reported in this study. The crystalline phase, morphology, oxidation states of elements, surface composition and optical properties of the photocatalysts were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy, respectively. The photocatalytic activity was evaluated by the degradation of methylene blue (MB) under visible-light irradiation, indicating that SnSe exhibits excellent photocatalytic performance with a maximum % degradation efficiency of MB up to 92.91% after 40 min of light irradiation. These materials were also used as photocatalysts for the degradation of Congo red (CR) and the results showed 98% degradation of Congo red which is much higher than other photocatalysts. The possible degradation pathway is also presented. Indeed, SnSe nanostructures with variable tin ratios behaved as highly efficient photocatalysts and could be promising for future industrial applications for wastewater treatment.

In this article, activated carbon was produced from Lantana camara and olive trees by H₃PO₄ chemical activation. The prepared activated carbons were analyzed by characterizations such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, X-ray diffraction, thermogravimetric analysis, and Fourier transform infrared spectroscopy. H₃PO₄ is used as an activator agent to create an abundant pore structure. According to EDX analysis, the crystalline structure destroys and increases the carbon content of the olive tree and Lantana camara by 77.51 and 76.16%, respectively. SEM images reveal a porous structure formed as a result of H₃PO₄ activation. The Brunauer–Emmett–Teller (BET) surface area of the olive tree and Lantana camara activated carbon was 611.21 m²/g and 167.47 m²/g, respectively. The TGA analysis of both activated carbons shows their thermal degradation starts at 230 °C but fully degrades at temperatures above 450 °C. To quantify the potential environmental implications related to the production process of the activated carbon (AC) from olive trees, the life cycle assessment (LCA) environmental methodology was employed. For most of the tested indicators, chemical activation using H₃PO₄ showed the greatest ecological impacts: the ozone layer depletion potential (42.27%), the acidification potential (55.31%), human toxicity (57.00%), freshwater aquatic ecotoxicity (85.01%), terrestrial ecotoxicity (86.17%), and eutrophication (92.20%). The global warming potential (5.210 kg CO₂ eq), which was evenly weighted between the phases, was shown to be one of the most significant impacts. The total energy demand of the olive tree’s AC producing process was 70.521 MJ per Kg.

Recently, there is growing concern over environmental pollution rising specifically from the water contamination due to industrial wastes that primarily comprise of organic dyes such as the Congo Red (CR) dye. On the other hand, semiconductors based nanomaterials have proven to be a powerful remediation tool for the polluted environment. Here in, we report an in situ approach for the development of strong interface via one pot hydrothermal synthesis of ZnTe/ZnSe heterostructures by precisely adjusting the chalcogens (Te/Se) concentration. The as-synthesized photocatalysts have further been characterized via various analytical techniques including X-ray diffraction for the phase confirmation, scanning electron microscopy together with energy dispersive X-ray spectroscopy for the morphological as well compositional analysis, and X-ray photoelectron spectroscopy along with UV–Vis diffuse reflectance spectroscopy to plot the alignment of energy levels. Finally, the synthesized heterostructures have been employed as potential photocatalysts for the UV–visible induced degradation of the CR dye. The results reveal remarkable efficacy where heterostructured photocatalysts exhibit enhanced degradation efficiency for up to ~ 94% in 65 min. The synergy between the individual counterparts in heterostructure i.e. ZnTe and ZnSe, via the formation of a strong interface plays a significant role in photocatalytic CR fixation by suppressing the charge recombination which is also the key issue in these semiconductor nanomaterials.

In the present paper, simple hydrothermal and solid-state methods are reported for the synthesis of metal chalcogenide (ZnSe), metal oxide (Co₃O₄) and their nano-heterostructure (ZnSe/Co₃O₄ 3:1, 1:1 and 1:3 ratios by weight), while their photocatalytic efficiencies are also investigated. The X-ray diffraction results corroborate the good crystallinity and purity of all synthesized products, i.e., ZnSe, Co₃O₄ and their nanocomposites. The scanning electron micro-images of ZnSe show a mixed morphology of nanoparticles (≈16 nm), including spherical and distorted cubes, while Co₃O₄ has a worm-like morphology (≈20 × 50 nm). The EDX results show that all the elements are present in accordance with their anticipated amounts in the products. The UV/visible absorption spectrum of ZnSe depicts a sharp absorption at around 480 nm, while Co₃O₄ demonstrates two prominent peaks, 510 nm and 684 nm. The prepared samples were employed for the photocatalytic degradation of Congo red dye and the nano-heterostructure (ZnSe/Co₃O₄ 3:1) shows an exceptional photocatalytic degradation efficiency of 96%. This enhanced photocatalytic activity was due to the synergic effect of ZnSe and Co₃O₄ that reduced the electron/hole recombination and caused suitable bandgap alignment.