Fast and efficient degradation of water pollutant dyes and fungicide by novel sulfur-doped graphene oxide-modified Ag3PO4 nanocomposite

The sulfur-doped graphene oxide (sGO)-integrated Ag₃PO₄ composite displayed very high catalytic activity toward prominent water pollutants like textile dyes and fungicide under sunlight. The optimum amount of sGO doping was found as 5% for degradation. The novel composite degraded 99% of methylene blue (MB) in only 5 min of sunlight exposure, which is 16 and 8 times faster than Ag₃PO₄ and 5% GO-Ag₃PO₄. High mineralization was observed for MB with a total organic carbon (TOC) removal of 98% in 30 min. The composite mineralized rhodamine B, methyl orange, and acid red 18 dyes with a TOC removal above 95%. Moreover, a toxic dithiocarbamate fungicide thiram was degraded in 1 h with a TOC removal of 82% leaving less toxic thiourea. The formation of sGO-Ag₃PO₄ n-n heterojunction increases charge transport and photocatalytic activity of the composite to incredible extent along with hollow morphology and in situ formed Ag nanoparticles (AgNPs).

Rapid sunlight-driven mineralisation of dyes and fungicide in water by novel sulphur-doped graphene oxide/Ag3VO4 nanocomposite

A semiconductor photocatalyst was prepared in facile, standard conditions by integrating 1% metal-free, sulphur-doped graphene oxide (sGO) as cocatalyst and Ag₃VO₄ as photocatalyst and characterised via spectroscopic, microscopic and voltammetric techniques. The catalytic activity was performed on notable water pollutants like textile dyes and fungicide employing various techniques. Cationic dyes such as methylene blue and rhodamine B were degraded > 99% with above 90% organic carbon content removal indicating total mineralisation while anionic dyes were degraded 75-80% in 1 h. For the first time, a dithiocarbamate fungicide thiram is degraded to give thiourea as a product in 1 h. Photocatalysis follows pseudo-first order kinetics with rate 3.67, 49.50 and 3.19 times higher than Ag₃VO₄, sGO and GO-Ag₃VO₄ respectively with excellent stability and recyclability. One percent sGO aided excellent carrier separation boosted by electrons and surface defects from sGO, morphology and n-n heterojunction formation. The catalyst efficiently removed 82.8% of the total organic carbon content of a real water sample from the textile mill under 2-h sunlight irradiation.

Novel La(OH)3-integrated sGO-Ag3VO4/Ag nanocomposite as a heterogeneous photocatalyst for fast degradation of agricultural and industrial pollutants

The composite described couples the benefits of hydroxyl radical formation from sunlight-inactive La(OH)₃ and strong sunlight absorption by Ag₃VO₄.

Ultrasonic assisted synthesis with enhanced visible-light photocatalytic activity of NiO/Ag3VO4 nanocomposite and its antibacterial activity

The NiO/Ag₃VO₄ nanocomposite photocatalysts were developed by ultrasonic assisted preparation method to study the photocatalytic activity under visible light irradiation. The samples were characterized by UV-DRS, XRD, FT-IR, XPS, SEM, EDX, TEM, EIS and BET analysis. The photocatalytic activity of NiO/Ag₃VO₄ nanocomposite for the photodegradation of 4-Nitro Phenol (4-NP) and Rose Bengal (RB) under visible light irradiation was studied and it is observed that the activity has been much higher than that of the pure Ag₃VO₄. DRS spectrum shows the absorption edge of NiO-Ag₃VO₄ in visible region of spectrum. The formation of cubic structured NiO and orthorhombic structured Ag₃VO₄ was confirmed by powder X-ray diffraction analysis. The results of XPS analysis confirmed the coexistence of NiO and Ag₃VO₄ in the NiO/Ag₃VO₄ composite. The specific surface area and pore structure of the prepared samples were measured by BET. Enhanced charge separation efficiency was confirmed by electrochemical impedance spectroscopy (EIS) measurements. The kinetics of the NiO/Ag₃VO₄ nanocomposite was proposed to investigate the intervened effects of NiO to Ag₃VO₄ on the promotion of photocatalytic property. NiO/Ag₃VO₄ was found to be stable and reusable without appreciable loss of catalytic activity up to four consecutive cycles. A possible electron-hole transfer mechanism at the NiO/Ag₃VO₄ interface is proposed. It also showed effective and efficient bactericidal activities against Staphylococcus aureus, Streptococcus, Proteus and Escherichia coli bacteria. Our results provide some new insights on the performance of visible light photocatalysts on environmental remediation.

Ag-Vanadates/GO Nanocomposites by Aerosol-Assisted Spray Pyrolysis: Preparation and Structural and Electrochemical Characterization of a Versatile Material

In this article, we describe the deposition by aerosol-assisted spray pyrolysis of different types of silver vanadate nanocomposites with and without graphene oxide (GO) on different substrates (carbon paper (CP) and fluorine-doped tin oxide (FTO)). When deposited on CP, different amounts of GO were added to the Ag and V precursor solution to study the effect of GO on the physicochemical properties of the resulting Ag-vanadate. It is shown that the addition of GO leads mainly to the formation of nanoparticles of the Ag2V4O11 phase, whereas Ag2V4O11 and Ag3VO4 are obtained without the addition of GO. The morphology and chemical properties of the composites were determined by scanning and transmission electron microscopies, X-ray diffraction, X-ray photoemission spectroscopy, and UV-visible and Raman spectroscopies. In addition, the photoelectrochemical (PEC) properties of such composites were studied by CV, linear sweep voltammetry, and electrochemical impedance spectroscopy. The ideal Ag x VO y and GO ratio was optimized for obtaining higher photocurrent values and a good stability. The results showed that the presence of GO improves the electrical conductivity of the catalyst layer as well as the electron injection from the oxide to the electrode surface. The deposition of pure Ag2V4O11 on FTO does not lead to samples with stable PEC performances. Samples grown on CP supports showed an efficient electrochemical detection of small amounts of ethylenediamine in water solution.

Preparation of silver/reduced graphene oxide coated polyester fabric for electromagnetic interference shielding

In this study, silver/reduced graphene oxide (Ag/RGO) coated polyester (PET) fabrics with dopamine as adhesive agent were prepared through an efficient chemical reduction method under microwave irradiation.

Copper-modified TS-1 catalyzed hydroxylation of phenol with hydrogen peroxide as the oxidant

The Cu²⁺ species and framework Ti of the Cu/TS-1-2 catalyst can promote the phenol hydroxylation reaction.

Novel visible-light-driven Fe2O3/Ag3VO4 composite with enhanced photocatalytic activity toward organic pollutants degradation

Photoactivity of Ag₃VO₄ can be enhanced by modification with Fe₂O₃. The electrochemical impedance of the composite being smaller than pure Ag₃VO₄ may be one reason.

BaTiO3–graphene nanocomposites: synthesis and visible light photocatalytic activity

The new role of graphene as a macromolecular photosensitizer transforms the wide band gap BaTiO₃ to have visible light photoactivity.

Selective photoredox using graphene-based composite photocatalysts

Graphene (GR) has proven to be a promising candidate to construct effective GR-based composite photocatalysts with enhanced catalytic activities for solar energy conversion. During the past few years, various GR-based composite photocatalysts have been developed and applied in a myriad of fields. In this perspective review, compared with the traditional applications of GR-based nanocomposites for the "non-selective" degradation of pollutants, photo-deactivation of bacteria and water splitting to H2 and O2, we mainly focus on the recent progress in the applications of GR-based composite photocatalysts for "selective" organic transformations, including reduction of CO2 to renewable fuels, reduction of nitroaromatic compounds to amino compounds, oxidation of alcohols to aldehydes and acids, epoxidation of alkenes, hydroxylation of phenol, and oxidation of tertiary amines. The different roles of GR in these GR-based nanocomposite photocatalysts such as providing a photoelectron reservoir and performing as an organic dye-like macromolecular photosensitizer have been summarized. In addition, graphene oxide (GO) as a co-catalyst in GO-organic species photocatalysts and GO itself as a photocatalyst for selective reduction of CO2 have also been demonstrated. Finally, perspectives on the future research direction of GR-based composite photocatalysts toward selective organic redox transformations are discussed and it is clear that there is a wide scope of opportunities awaiting us in this promising research field.