Ash based nanocomposites for photocatalytic degradation of textile dye pollutants: A review

Biological mediated synthesis of RGO-ZnO composites with enhanced photocatalytic and antibacterial activity

Synthesis and characterization of novel ZnO/NiCr2O4 nanocomposite for water purification by degradation of tetracycline and phenol under visible light irradiation

ZnO is an exciting material for photocatalysis applications due to its high activity, easy accessibility of raw materials, low production costs, and nontoxic. Several ZnO nano and microstructures can be obtained, such as nanoparticles, nanorods, micro flowers, microspheres, among others, depending on the preparation method and conditions. ZnO is a wide bandgap semiconductor presenting massive recombination of the generated charge carriers, limiting its photocatalytic efficiency and stability. It is common to mix it with metal, metal oxide, sulfides, polymers, and nanocarbon-based materials to improve its photocatalytic behavior. Therefore, ZnO–nanocarbon composites formation has been a viable alternative that leads to new, more active, and stable photocatalytic systems. Mainly, graphene is a well-known two-dimensional material, which could be an excellent candidate to hybridize with ZnO due to its excellent physical and chemical properties (e.g., high specific surface area, optical transmittance, and thermal conductivity, among others). This review analyses ZnO–graphene nanocomposites’ recent advances, addressing the synthesis methods and the resulting structural, morphological, optical, and electronic properties. Moreover, we examine the ZnO–graphene composites’ role in the photocatalytic degradation of organic/inorganic pollutants.

Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

Titanium dioxide is a compound of great interest, due to its functional properties; one of its most important uses is as a photocatalyst TiO2 coatings can be deposited using different techniques Aerosol Assisted Chemical Vapour Deposition (AACVD) is particularly interesting, as high temperature or pressure are not necessary to generate the gaseous precursors Furthermore, by carefully choosing the deposition conditions (ie deposition temperature, solvent), it is possible to obtain deposits with different morphology and, consequently, different functional properties In this paper we present the synthesis of titanium dioxide coatings with AACVD using complexes between titanium isopropoxide (TIPP) and acetyl acetone (acac) as precursors Deposition experiments were performed using different ratios of TIPP to acac, to assess the effect on the composition of the coatings, their morphology and photocatalytic activity Results showed that the use of acac led to nanostructured titanium dioxide (nanoparticles of about 10−25 nm diameter) Raman analysis showed the presence of both anatase and rutile phases XPS analysis indicated the presence of residual carbonaceous species in the coatings; despite this, they displayed photocatalytic properties similar or superior to AACVD films without carbon Photocatalytic tests, performed measuring the Formal Quantum Efficiency (FQE) and the Formal Quantum Yield (FQY) in the degradation of resazurin, showed that a acac:TIPP ratio equal to 1 led to the material with the highest performance, as the FQE value was about three times higher than that for the coating prepared with TIPP alone Overall the complexes between TIPP and acac are promising precursors for the AACVD technique, leading to nanostructured coatings with enhanced performance

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Nanostructured titanium dioxide coatings prepared by Aerosol Assisted Chemical Vapour Deposition (AACVD)

Effective solar energy harvested through material engineering is a promising technique for both environment and energy applications. Current researches show the role of metal oxide photocatalyst for efficient solar energy harvesting. Among various techniques for improving the photocatalytic performance, structural engineering is one of the effective methods to enhance the surface area and photon absorption of the metal oxide along with effective charge carrier separation. Keeping this in mind, a detailed review on various nanostructures of ZnO as photocatalyst has been carried out to explore the role of nanostructures in improving the photocatalytic performance under various irradiation conditions. The review reveals that structural engineering can enhance the photocatalytic performance of ZnO drastically compared to the conventional one. This perceptive article helps to understand the role of structural engineering in enhancing the photocatalytic performance of ZnO.

Influence of surface morphology on photocatalytic performance of zinc oxide: A review

Role of copper and silver modified titania photoanode on performance engineering of dye sensitized solar cells

Herein, we report the synthesis of Cu doped ZnO photocatalysts through coprecipitation method. In order to investigate the role of Cu in ZnO matrix to improve the photocatalytic performance, structural, morphological, compositional and optical properties were studied. The structural study reveals the formation of wurtzite ZnO phase without involving any secondary phase with average crystallite size within nano range. FESEM analyses revealed that the pristine and doped ZnO exhibit interesting flake like morphology. Photocatalytic activity of the samples was examined under visible light irradiation. Cu doped ZnO outperformed pristine ZnO, this could be mainly attributed to the enhanced optical properties as revealed from UV-Vis and PL analyses. The incorporation of Cu ions into ZnO matrices enhances the optical properties to a great extent. The red shift in the absorption towards visible region and reduced charge carrier recombination plays the vital role in improvement of photocatalytic performance of doped sample. The increased photocatalytic performance of Cu modified ZnO is discussed in detail based on its different physico-chemical properties.

Cu doped ZnO as an efficient visible active photocatalyst

Titania (TiO2) based photocatalytic water spitting has excellent potential for hydrogen production. However, the poor light-harvesting capacity and high recombination rate of photoinduced electron–hole pairs limit its performance. Therefore, doping of TiO2 with metal/non-metal ions can be a practical approach to improve the performance of TiO2 for efficient photocatalytic H2 production. Along with the role of dopants, various synthesis parameters also contribute to the performance of TiO2. Considering this, the present study has shown the influence of pH in the performance of C-doped TiO2. C-doped TiO2 under various pH values (3,7,11) was synthesised via the sol–gel method. The structural morphological and optical characterisation was performed using XRD, FESEM and UV–Vis spectroscopy. The C doping was confirmed through EDS. The samples were further tested for hydrogen production. It was observed that the C-dopedTiO2 synthesised under pH 7 produced hydrogen gas at a rate of 1142.4 µmol/g/h, which is about 3 times and 1.5 times greater than that produced by samples synthesised under pH 3 and 11 conditions. The superior performance of the photocatalyst at the optimum pH value indicates the role of pH tuning on the performance of C doped TiO2 for efficient H2 production.

S. K. Nikhil

Papers

Influence of surface morphology on photocatalytic performance of zinc oxide: A review

Role of copper and silver modified titania photoanode on performance engineering of dye sensitized solar cells

Cu doped ZnO as an efficient visible active photocatalyst

Performance Engineering of C-Doped Titania for Photocatalytic Hydrogen Production Through pH Tuning