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

A series of coupled ZnO-SnO2 photocatalyst was successfully synthesized in the Zn:Sn molar ratio of 20:1, 10:1, 5:1 and 2:1 via co-precipitation method followed by calcination at different temperatures. The synthesized materials were characterized by X-ray diffraction, diffuse reflectance spectra, scanning electron microscope and transmission electron microscope. Photocatalytic activitiy of synthesized materials was applied for the degradation of cibacron red dye in aqueous solution under UV-A light irradiation. Experimental results revealed that the coupled ZnO-SnO2 photocatalyst with Zn:Sn molar ratio 10:1, calcined at 600oC for 1 h was the most efficient photocatalyst among synthesized samples for the degradation of cibacron red. Superoxide anion radical (•O2–) was found to be the prominent active species responsible for degradation comparative to hole (h+), hydroxyl radical (•OH).

Synthesis and Charcterization of Coupled ZnO/SnO2 Photocatalysts and Their Activity towards Degradation of Cibacron Red Dye

The biomedical properties of nanoparticles have been the area of focus for contemporary science; however, there are issues concerning their long-term toxicities. Recent trends in nanoparticle fabrication and surface manipulation, the use of distinctive biogenic capping agents, have allowed the preparation of nontoxic, surface-functionalized, and monodispersed nanoparticles for medical applications. These capping agents act as stabilizers or binding molecules that prevent agglomeration and steric hindrance, alter the biological activity and surface chemistry, and stabilize the interaction of nanoparticles within the preparation medium. Explicit features of nanoparticles are majorly ascribed to the capping present on their surface. The present review article is an attempt to compile distinctive biological capping agents deployed in the synthesis of metal nanoparticles along with the medical applications of these capped nanoparticles. First, this innovative review highlights the various biogenic capping agents, including biomolecules and biological extracts of plants and microorganisms. Next, the therapeutic applications of capped nanoparticles and the effect of biomolecules on the efficiency of the nanoparticles have been expounded. Finally, challenges and future directions on the use of biological capping agents have been concluded. The goal of the present review article is to provide a comprehensive report to researchers who are looking for alternative biological capping agents for the green synthesis of important metallic nanoparticles.

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Role of Biogenic Capping Agents in the Synthesis of Metallic Nanoparticles and Evaluation of Their Therapeutic Potential

Ultrasonic studies of molecular interactions in binary mixtures of formamide with some isomers of butanol at 298.15 K and 308.15 K

BaAl2O4:Eu2+/Eu3+ (1 mol %) co-doped with varying concentrations of Gd3+ (1, 2, 5 and 10 mol%) were prepared by combustion synthesis method at 600°C. All the compositions were investigated for their structural and photoluminescence properties. Samples prepared in open atmosphere showed the presence of both Eu3+ and Eu2+ states which indicates the reduction of Eu3+ to Eu2+ during the preparation of these compounds. The prepared materials at 600°C showed high intense broad peaks around 498 nm corresponding to Eu2+ and small peaks in the red region which are attributed to the presence of Eu3+. In the 1000°C annealed compounds, the intensity of the peak at 498 nm got increased. The intensity of this broad band for BaAl2O4:Eu2+/Eu3+(1 mol%):Gd3+(1 mol%) was three times than that of BaAl2O4:Eu2+/Eu3+(1 mol%). Thus second rare earth ion (Gd3+) acted as a good sensitizer and enhanced the photoluminescence intensity. The XRD spectra revealed the presence of hexagonal phase of BaAl2O4 as main phase and a small amou...

Naveen Verma

Papers

Synthesis and Charcterization of Coupled ZnO/SnO2 Photocatalysts and Their Activity towards Degradation of Cibacron Red Dye

Role of Biogenic Capping Agents in the Synthesis of Metallic Nanoparticles and Evaluation of Their Therapeutic Potential

Ultrasonic studies of molecular interactions in binary mixtures of formamide with some isomers of butanol at 298.15 K and 308.15 K

Luminescence Properties of Eu2+/Eu3+ Activated Barium Aluminate Phosphors with Gd3+ Concentration Variation

Volumetric properties of sec- and tert-butyl chloride with benzene, toluene and xylenes at 308.15 K