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Mixed multimetallic-based nanocomposites have been considered a promising functional material giving a new dimension to environmental remediation and energy storage applications. On this concept, a hybrid ternary CoO/Ni(OH)2/Cu(OH)2 (CNC) composite showing sea-urchin-like morphology was synthesized via one-pot hydrothermal approach, and its photocatalytic and electrochemical performances were investigated. The photocatalytic performance was explored using Congo red (CR) as a dye pollutant under visible light illumination. The presence of mixed phases of ternary metal ions could minimize the recombination efficacy of photogenerated charge carriers on the basis of the heterojunction mechanism, resulting in 90% degradation of CR dye (40 mg L−1). The effect of scavengers coupled with electrochemical experiments revealed O2−. radical as the predominating species responsible for the degradation of CR. From the electrochemical analysis of CNC, the well-distinguished redox peaks indicated the redox-type nature with a specific capacity of 405 C g−1. For practical applications, an supercapattery (CNC(+)|KOH|AC(−)) was assembled furnishing an energy density of 42 W h kg−1 at a power density of 5160 W kg−1 at 5 A g−1 along with a high capacity retention and coulombic efficiency of 98.83% over 5000 cycles. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of nitrate waste into ammonia allows both the removal of nitrate contaminants and an alternative production of ammonia compared to the classical Haber–Bosch industrial process. Ammonia is useful in agriculture for manufacturing fertilizers, and as a reagent in pharmaceuticals, metallurgy, explosives, and the textile industry; ammonia is also an energy carrier in the automobile industry for next-generation fuel cells. Here we review the nitrate-to-ammonia conversion by electrocatalysis of industrial and agricultural waste, with focus on catalysts, reaction intermediates, side reactions, and reaction conditions. Electron transfer is facilitated by electrocatalysts with transition metals having occupied d-orbitals with similar energy levels to that of the nitrate lowest unoccupied molecular orbital. Green electro-conversion using carbon-based materials is also discussed. Results show nitrate conversion from 53 to 99.8% and ammonia selectivity from 70 to 97.4%. [ABSTRACT FROM AUTHOR]

Recent trends in optoelectronics still need a highly efficient photodetector based on p-type metal oxide semiconductors. This work stands with the improvement in the performance of CuO thin films via doping with different metals into the thin films. The CuO thin films were successfully doped with 1 wt% of X (X = Al, Ga, and In) by spray pyrolysis method. The prepared doped CuO thin films were characterized to interpret the structural, morphological, and elemental characteristics using advanced techniques. These doped CuO thin films were subjected to study the photodetection ability by analyzing optoelectronic properties. The doping also tuned the optical and electrical properties. Among the fabricated photodetectors, the Al-doped CuO detector shows a maximum photocurrent. The CuO:Al (1.0%) thin film exhibits a high photocurrent of 2.59 × 10−6 A, the responsivity of 2.82 × 10− 1 AW− 1, the external quantum efficiency of 66%, and the detectivity of 1.45 × 1010 Jones. Compared to the other thin films, Al doping has remarkably reduced the bandgap and shows a good photosensing activity that may be due to an increase in charge carriers. These outcomes provide a way to assemble good photodetectors and tune their properties in a wide range. [ABSTRACT FROM AUTHOR]

Attaining a sustainable environment has become a prime area of research interest, as it is an utmost necessity for a healthy life. Hence, ample studies have been carried out in adopting different processes and utilizing various materials to attain the goal. Herein, we present an exclusive discussion on one such material, i.e., polyaniline (PANI) and its derivatives. Being an intrinsic conducting type, it has grabbed more attention due to its durability in different doped/un-doped states, promptness in structural alteration, and solution processability. This review presents an exhaustive discussion on published reports showing utilization of PANI and its derivative in various forms like pure and composites, for cleaning the environment through adsorption, photodegradation, etc., and the various methods adopted in order to achieve an optimum operating condition to obtain the maximum outcome. In addition to these merits and demerits, various technical challenges faced with materials have been also presented. Therefore, it is expected that this piece of work, presenting the exhaustive discussion on PANI and; its derivatives would help to develop a better understanding of this excellent conducting polymer PANI and provide a state of art on the role of this material for attaining sustainable surroundings for the living beings. [ABSTRACT FROM AUTHOR]

The influence of Ag doping on the SnO2 sensor operating at room temperature is reported in this work. The SnO2 and Ag-doped SnO2 films are deposited by the nebulizer spray pyrolysis method with different Ag (1, 2, 3, and 4 wt%) concentrations. The characterization of doped thin films was done using multiple advanced techniques to understand their crystallization, morphology, optical and electrical properties to find the optimized Ag concentration on the SnO2 surface. It was found that the doping of different concentrations into the SnO2 lattice increases the preferential orientation of the peak along (211) plane up to 3wt% Ag and starts decreasing at 4 wt%. The estimated crystallite size of the 3wt% Ag-doped SnO2 thin films shows larger value of 98 nm with improved thickness and decreased strain. The morphologies of all the prepared thin films exhibits small leafy flakes structure with change in the particle size and improved agglomeration with increased Ag concentration. The optical studies showed better transparency in the visible and near-IR regions with decreased transmittance and increase in bandgap with increasing Ag concentration in SnO2. The PL results suggest that the 3wt% Ag-doped SnO2 has high-intensity emission peaks over the visible regions indicating the presence of more oxygen vacancies which acts as recombination centers to trap large amount of target gas. Finally, the gas sensing properties of the samples at different concentration of ammonia gas (i.e., 50, 100, 150, 200, and 250 ppm) are studied, which revealed that the 3wt% Ag-doped SnO2 showed better sensitivity/response of 120% with maximum response and recovery times of 32 and 17 s at 250 ppm of ammonia gas. Thus, the undoped SnO2 has been optimized with different doping amounts of Ag ions to obtain the best ammonia sensor. [ABSTRACT FROM AUTHOR]

The wastewater treatment is a challenging research area to reduce the increasing pressure on limited fresh water resources. Amongst several techniques adopted and practiced, adsorption is one of the most effective and sustainable ecofriendly processes. In recent years, MXene nanomaterials, a new family of transition metal carbides, have gained increasing attention as the potential adsorbent for pollutants due to their unique features such as large surface area with abundant active sites and hydrophilicity. A wide range of pollutants viz. heavy metal ions, organic dyes, radionuclides, and toxic gas molecules have been sensed by 2D MXenes. An inclusive understanding on the adsorptive behavior of MXene-based materials is needed to explain the removal mechanism and effects of different adsorption parameters. This review gives a general overview on recent research progress on MXene materials with special reference to their applications for the adsorptive removal of different pollutants. The general trends in the synthesis of MXenes, their stability and different factors affecting the adsorption process along with the main challenges in understanding the full potential of MXenes for environmental applications are discussed. [ABSTRACT FROM AUTHOR]

CuO thin films deposited using SILAR coating technique with various dip-cycles. The prepared thin films were characterized to elucidate the structural and morphological features using analytical techniques such as XRD and SEM, respectively. It was found that along with the thickness of CuO films, the crystallinity and morphology of the deposited films have changed appreciably. The optical, electrical, and photosensing properties were also studied for deposited films. The optical and electrical properties for the thin film prepared with 100 dip-cycles were found best as compared to 50, 75, 125 dip-cycles, this may be due to improved crystallinity and uniform distribution of nanoclusters over the substrate. From the UV absorption studies, it was found that the CuO-100 thin-film has the highest absorption and a low bandgap of 1.67 eV. Also, the CuO with 100 dip sample exhibits a minimum resistivity of 2.98 × 102 Ω cm that leads to a higher carrier concentration of 4.63 × 1013 cm−3 and mobility of 4.53 cm2V−1 s−1. The I–V characteristics of all the deposited CuO samples were investigated and the CuO-100 dip cycle thin film is found to have a lower ideality factor of 5.4. Additionally, the Cu-100 thin film reveals a high responsivity and external quantum efficiency values of 1.67 × 10−1 A/W and 54%, respectively. Thus, in the SILAR dip-coating technique, the dipping cycles influence the CuO formation as well as their properties. [ABSTRACT FROM AUTHOR]