In the past few decades, many novel non-metal doped ZnO materials have developed hasty interest due to their adaptable properties such as low recombination rate and high activity under the solar light exposure. In this article, we compiled recent research advances in non-metal (S, N, C) doped ZnO, emphasizing on the related mechanism of catalysis and the effect of non-metals on structural, morphological, optical and photocatalytic characteristics of ZnO. This review will enhance the knowledge about the advancement in ZnO and will help in synthesizing new ZnO-based materials with modified structural and photocatalytic properties.

S-, N- and C-doped ZnO as semiconductor photocatalysts: A review

Advanced oxidation process (AOP) is a versatile photocatalytic approach to degrade various environmental pollutants. Among many photocatalysts used in AOP such as ZnO, TiO2, ZrO2, ZnS, CdS; TiO2 is the most widely adopted semiconductor material. TiO2 is a wide band gap material and absorb in UV spectrum which is a narrow region in the sun light. This benchmark makes it a less efficient photocatalyst under sunlight irradiation. To enhance the photocatalytic efficiency, the absorption band of photocatalyst should be modified in such a way that it leads to maximum absorption in the solar spectrum. The doping of nonmetals such as N, C, P and S etc. shift the band edge of the semiconductors towards the visible region and thus increases the photon absorption which successively enhances the photocatalytic efficiency. In this review, we have focused on effect of nonmetal doping on the properties and photocatalytic activity of the TiO2. Influence of various aspects such as synthesis procedure, doping source, concentration of dopant, calcination etc. are also explored towards alteration in properties and photocatalytic efficiency of nonmetals doped TiO2.

Non-metal modified TiO2: a step towards visible light photocatalysis

In this work, novel Cu2O/PbBiO2Br heterojunction composites have been successfully prepared by hydrothermal method and oxidation–reduction process. The structure, morphology, optical and electronic properties of the as-prepared photocatalysts were investigated by various techniques. It is demonstrated that PbBiO2Br appears a smooth brick-like nanostructure and the average size is about 20–110 nm. The PbBiO2Br nano-bricks are dispersed on the surface of Cu2O particles to form Cu2O/PbBiO2Br p-n heterostructures. Compared with pure PbBiO2Br and Cu2O, the Cu2O/PbBiO2Br heterojunction composites exhibit enhanced photocatalytic performances for the degradation of crystal violet (CV) solution under visible-light irradiation. In particular, the 5%Cu2O/PbBiO2Br composite shows the optimal photocatalytic performance, and the degradation efficiency of CV reaches 96% in 50 min. The enhanced photocatalytic performance of the Cu2O/PbBiO2Br composites can be attributed to the significantly enhanced absorption in the visible range and efficient separation of photo-generated electron–hole pairs due to the formation of Cu2O/PbBiO2Br p-n heterostructures. Furthermore, the radical trapping experiments indicate that $$\cdot {\text{O}}_{2}^{ - }$$
 radicals and holes are the main active species during the decomposition process. Based on the experimental results and analyses, a possible photocatalytic mechanism of the Cu2O/PbBiO2Br composites is proposed. This study reveals that the Cu2O/PbBiO2Br composite photocatalysts could be applied in the wastewater purification.

Construction of novel Cu2O/PbBiO2Br composites with enhanced photocatalytic activity

The present work shows the mechanical behavior of as-cast A356 alloy and A356-4 wt% graphite (Gr)-12 wt% boron carbide (B4C) hybrid composites. The hybrid composite samples were developed by two stage stir casting technique. The developed hybrid composites were subjected to scanning electron microscope (SEM) and energy dispersive spectroscope to analyze its microstructure followed by physical and mechanical tests like density, hardness, and tensile tests. The SEM analysis showed almost uniform distribution of particulates; also, hardness and tensile properties improved upon addition of reinforcement viz., graphite and B4C. The density of hybrid composite decreased upon addition of reinforcement when compared with base A356 alloy. Fractography of tensile specimens were carried out for analysis of fractured surfaces.

Mechanical behavior and fractography of graphite and boron carbide particulates reinforced A356 alloy hybrid metal matrix composites

ZnO-based heterostructures as photocatalysts for hydrogen generation and depollution: a review

Anodic Oxide Films on Niobium and Tantalum in Different Aqueous Electrolytes and Their Impedance Characteristics N. Vermaa,∗, K.C. Singh, B. Mari, M. Mollar and J. Jindal Department of Chemistry, Maharshi Dayanand University, Rohtak 124001, Haryana, India Institut de Disseny per la Fabricacio Automatitzada, Departament de Fisica Aplicada, Universitat Politecnica de Valencia, Cami de Vera s/n, 46022 Valencia, Spain

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Anodic Oxide Films on Niobium and Tantalum in Different Aqueous Electrolytes and Their Impedance Characteristics

Porous anodic aluminum oxide film is a versatile template for the fabrication of nanomaterials. Porous alumina can be fabricated electrochemically through anodic oxidation of aluminum by self-organization method yielding highly ordered arrays of nanoholes. Various techniques such as chemical vapor deposition, electrodeposition, spin coating, dip coating, physical vapor deposition are elaborated for the fabrication of nanomaterials using porous anodic alumina as template.

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Fabrication of Nanomaterials on Porous Anodic Alumina Template Using Various Techniques

Ta2O5:Eu3+: Mg2+ or Ca2+ phosphor materials were prepared by molten salt method using KCl as flux. The X-ray diffraction (XRD) patterns illustrated that the well crystallized Ta2O5:Eu3+: Mg2+ or Ca2+ were formed in the presence of flux under reduced temperature (800 °C) in contrast to conventional solid state method (1200-1500 °C). Scanning electron microscope (SEM) images indicate the achievement of well dispersed particles (hexagonal tablet and rod-like structures). Meanwhile, the photo-luminescent studies demonstrated that Ta2O5 is an efficient host to sensitize europium red emissions. The addition of Mg2+ or Ca2+ as co-dopant enhanced the luminescent intensity of Ta2O5: Eu3+ compound.

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Structural and optical properties of Ta2O5:Eu3+: Mg2+ or Ca2+ phosphor prepared by molten salt method

The Zn(1-x-y)MoO4:Eu3+(x): Y3+(y) (x = 1 mol% and y = 1 or 2 mol%) compounds were prepared by combustion synthesis method. The crystal structure of the samples was identified by X-ray diffraction (XRD). The photoluminescence properties were investigated and it is observed that the co-doping of Y3+ enhances the luminescence emission intensity of ZnMoO4:Eu3+ material. The Y3+ acts as a sensitizer in the ZnMoO4:Eu3+ lattice. The particle size is calculated from XRD data by using Scherer Equation. The particles has been found in the range of 30-40 nm.

Naveen Verma

Papers

Anodic Oxide Films on Niobium and Tantalum in Different Aqueous Electrolytes and Their Impedance Characteristics

Fabrication of Nanomaterials on Porous Anodic Alumina Template Using Various Techniques

Structural and optical properties of Ta2O5:Eu3+: Mg2+ or Ca2+ phosphor prepared by molten salt method

Luminescence properties of ZnMoO4:Eu3+:Y3+ materials synthesized by solution combustion synthesis method

Anodic Oxide Nanostructures: Theories of Anodic Nanostructure Self-Organization