Zinc iron selenide nanoflowers anchored g-C3N4 as advanced catalyst for photocatalytic water splitting and dye degradation.

Hydrogen has been considered as a promising clean energy source owing to its renewability and zero carbon emission. Accordingly, photocatalytic water splitting has drawn much attention as a key green technology of producing hydrogen. However, it has remained as a great challenge due to the low production rate and expensive constituents of photocatalytic systems. Herein, we synthesised nanostructures consisting of transition metal selenide and g-C3N4 for photocatalytic water splitting reaction. They include ZnSe, FeSe2, Zn/FeSe2 and ZnFeSe2 nanoflowers and a nanocomposite made of Zn/FeSe2 and g-C3N4. Hydrogen evolution rates in the presence of ZnSe, FeSe2, Zn/FeSe2 and ZnFeSe2 photocatalysts were measured as 60.03, 128.02, 155.11 and 83.59 µmolg-1 min-1, respectively. On the other hand, with the nanocomposite consisting of Zn/FeSe2 and g-C3N4, the hydrogen and oxygen evolution rates were significantly enhanced up to 202.94 µmol g-1min-1 and 90.92 µmol g-1min-1, respectively. The nanocomposite was also examined as a photocatalyst for degradation of rhodamine B showing that it photodegrades the compound two times faster compared to pristine Zn/FeSe2 nanoflowers without g-C3N4. Our study suggests the nanocomposite of Zn/FeSe2 and g-C3N4 as a promising photocatalyst for energy and environmental applications.

Photocatalytic degradation of tetracycline using hybrid Ag/Ag2S@BiOI nanowires: Degradation mechanism and toxicity evaluation.

The wide use of antibiotics has caused their continual release and persistence in the eco-system, subsequently giving birth to antibiotic resistant bacterial species in the aquatic environment, thereby necessitating immediate and efficient remediation of the contaminated environment. In the present study, we synthesized Ag/Ag2S@BiOI nanowires with an average diameter of ∼150 nm and length of 3-5 µm using a hydrothermal method and employed them as photocatalysts for photocatalytic degradation of tetracycline as a model antibiotic. The nanowire achieved nearly complete degradation of tetracycline (∼99%) within 60 min at the optimal condition of 100 mg/L TC concentration and pH 2. The degradation followed pseudo-first order kinetics, with a rate constant of 0.06228 min- 1. Our toxicity tests showed that the nanowire has negligible toxicity towards PBMC cells, suggesting it as a promising photocatalyst.

Highly efficient visible light photocatalysis of Nix Zn1-x Fe2O4 (x= 0, 0.3, 0.7) nanoparticles: Diclofenac degradation mechanism and eco-toxicity.

Pharmaceuticals and personal care products occupy a predominant position with respect to both utility and release into the ecosystem, thereby contributing to environmental pollution at alarming rates. Of the several methods identified to minimize the concentration of PPCPs, nanomaterial based photocatalysis seems to be a potential alternative for it being highly economical and eco-friendly. In this study, we synthesized Nickel zinc ferrite (Ni-ZF) [Nix Zn1-x Fe2O4 (x = 0, 0.3, 0.7)] nanoparticles with an average diameter of ∼400 nm by a co-precipitation method towards diclofenac degradation. The composite showed greater degrees of crystallinity devoid of any impurities. Nearly complete DCF degradation (∼99%) was achieved after 50 min reaction time with the nanoparticles at pH 7 for an initial DCF concentration of 50 mg/L. The degradation process followed a pseudo first-order rate law with the rate constant of 0.1657 min- 1. Microbial toxicity and phytotoxicity studies demonstrated negligible toxicity imposed by the contaminated water treated with the prepared composite, suggesting it as a promising photocatalyst benefitting in all aspects.

Nickel decorated manganese oxynitride over graphene nanosheets as highly efficient visible light driven photocatalysts for acetylsalicylic acid degradation.

In this work, we prepared nanocomposites of nickel-decorated manganese oxynitride on graphene nanosheets and demonstrated them as photocatalysts for degradation of acetylsalicylic acid (ASA). The catalyst exhibited a high degradation efficiency over ASA under visible light irradiation and an excellent structural stability after multiple uses. Compared to manganese oxide (MnO) and manganese oxynitride (MnON) nanoparticles, larger specific surface area and smaller band gap were observed for the nanocomposite accounting for the enhanced photocatalytic efficiency. Besides the compositional effect of the catalyst, we also examined the influence of various experimental parameters on the degradation of ASA such as initial concentration, catalyst dose, initial pH and additives. The best performance was obtained for the nanocomposite when the catalyst dose was 10 mg/mL and the initial pH 3. Detection of intermediates during photocatalysis showed that ASA undergoes hydroxylation, demethylation, aromatization, ring opening, and finally complete mineralization into CO2 and H2O by reactive species. For practical applications as a photocatalyst, cytotoxicity of the nanocomposite was also evaluated, which revealed its insignificant impact on the cell viability. These results suggest the nanocomposite of nickel-decorated manganese oxynitride on graphene nanosheets as a promising photocatalyst for the remediation of ASA-contaminated water.