• Energy Research

A flower-like molybdenum disulfide microspheres and various carbon materials (acetylene black, vulcan carbon, multi-walled carbon nanotubes, carbon nanofibers, and rice husk ash) incorporated MoS2 microsphere materials were synthesized via convenient single-step hydrothermal method. The obtained MoS2/C materials provide cost-effective and Pt free counter electrodes for DSSCs. Phthaloylchitosan-based polymer electrolyte was used as an electrolyte for DSSCs. The phase formation and purity of the synthesized materials were ascertained by powder X-ray diffractometer. The shape, morphology, and the distribution of the carbon materials in MoS2 microspheres were examined by electron microscope measurements. The electrochemical measurements were revealed that the carbon materials incorporated MoS2 electrode hold low charge transfer resistance at the counter electrode/electrolyte interface and demonstrate high electrocatalytic activity for the reduction of I3 − to I−ions. Among different carbon materials studied, MoS2 doped on CNF offered a positive synergistic effect for the electrocatalytic reduction of I3 −. The DSSC fabricated with MoS2/CNF CE and phthaloylchitosan-based polymer electrolyte shown a high power conversion efficiency of 3.17 %, whereas pure MoS2 CE showed only 1.04 %. The present study validates the application of carbon incorporated MoS2 as a potential CE in DSSCs.

Herein, we have examined the effect of tungsten trioxide (WO3) doping in graphitic carbon nitride (g-C3N4) photocatalysts towards photodegradation of organic pollutant in aqueous medium. A sequence of visible light driven WO3/g-C3N4 composites were synthesized at various mole ratios (1, 2, 3 and 5%) of WO3 into g-C3N4 via simple and short-time wet-impregnation method. The fabricated photocatalytic materials were investigated by X-ray diffraction (XRD), Fourier transform-infrared (FT-IR) spectroscopy, UV–vis diffuse reflection spectroscopy (DRS), photoluminescence (PL) and scanning electron microscopy (SEM). The photocatalytic performance of the fabricated photocatalysts were assessed by the degradation of acid orange 7 (AO7) in visible-light illumination. The WO3/g-C3N4 composites were found to be exhibit an improved visible-light induced photocatalytic performances compared to the pure WO3 and g-C3N4. However, among the different composites, the optimized 3 wt% WO3/g-C3N4 composite has shown complete (100%) degradation efficiency of AO7 after 75 min which is superior than the pure g-C3N4. This synergistic enhancement might be credited to its increased light absorption in visible-light region and the photoexcited electron transfer from g-C3N4 to WO3 catalyst surface and enhanced charge separation efficiency. Additionally, the photo-electrochemical measurements of 3 wt% WO3/g-C3N4 composite has exhibited a quicker migration of the photo-excited charge-carriers. The radical scavenging studies inferred that the O2·− are the key species accountable for the degradation of AO7 for fabricated WO3/g-C3N4 composite materials. Hence, the higher photocatalytic activity, long-term stability and recyclability of WO3/g-C3N4 composite has displayed it is a auspicious material for the photocatlytic degradation of organic contaminant applications.

The storage, utilization, and control of the greenhouse (CO2) gas is a topic of interest for researchers in academia and society. The present review article is dedicating to cover the overall role of ionic liquid-modified hybrid materials in cycloaddition reactions. Special emphasis is on the synthesis of various cyclic carbonate using ionic liquid-based modified catalysts. Catalytic activity studies have discussed with respect to process conditions and their effects on conversion and product selectivity for the reaction of cycloaddition of CO2 with styrene oxide. The reaction temperature and the partial pressure of CO2 have found to play a key role in cyclic carbonate formation. The role of other influential parameter (solvent effect) is also discussed for the conversion of cyclic/aromatic oxides to polycarbonate production. Our own research work that deals with ionic liquid-based halide-modified mesoporous catalyst (MCM-41 type) derived from rice husk waste has also been discussed. Finally, the role of carbon dioxide activation and ring-opening mechanisms involved in the cyclic carbonate product formation from CO2 have been discussed.

Abstract The demand for sustainable energy storage and production is vital and continues to grow with increasing human population. Energy utilization and environmental protection demand urgent attention in the development of energy devices, including the expansion and assessment of earth abundant and inexpensive materails. Recently, two-dimensional (2D) structured graphene has emerged as an outstanding energy material due to its excellent physicochemical properties, for example, high thermal and electrical conductivity, high surface area, strong mechanical strength, and an excellent chemical stability. However, pure graphene has a band gap of zero significantly limiting its application as a material. Among the various approaches used to alter the properties of graphene is doping with a heteroatom, which has been shown to be an efficient process in tailoring the properties of 2D-graphene. Heteroatom-doped graphene has several improved physicochemical properties, making graphene a favorable material for application in various fields. In this review, we report the usage and advancement of heteroatom-doped graphene materials in various energy conversion and storage technologies, including supercapacitors, batteries, dye-sensitized solar cells, and hydrogen production from electrocatalytic water splitting. Furthermore, we have also highlighted the recent developments made to date and systematically discuss physicochemical mechanisms, and the precise advantages obtained by the doping of heteroatoms. Finally, the challenges and future perspectives for heteroatom-doped graphene materials are outlined. The information provided in this review should be useful to any researchers involved in the field of graphene research for wide-ranging applications, and structural-oriented (morphology, structure, size and composition) research.

Platinum-free counter electrodes (CE) were developed for use in efficient and cost-effective energy conversion devices, such as dye-sensitized solar cells (DSSCs). Electrochemical deposition of CoS2 on fluorine-doped tin oxide (FTO) formed a hierarchical sheet-like structured CoS2 thin film. This film was engaged as a cost-effective platinum-free and high-efficiency CE for DSSCs. High stability was achieved using a phthaloychitosan-based gel-polymer electrolyte as the redox electrolyte. The electrocatalytic performance of the sheet-like CoS2 film was analyzed by electrochemical impedance spectroscopy and cyclic voltammetry. The film displayed improved electrocatalytic behavior that can be credited to a low charge-transfer resistance at the CE/electrolyte boundary and improved exchange between triiodide and iodide ions. The fabricated DSSCs with a phthaloychitosan-based gel-polymer electrolyte and sheet-like CoS2 CE had a power conversion efficiency (PCE, η) of 7.29% with a fill factor (FF) of 0.64, Jsc of 17.51 mA/cm2, and a Voc of 0.65 V, which was analogous to that of Pt CE (η = 7.82%). The high PCE of the sheet-like CoS2 CE arises from the enhanced FF and Jsc, which can be attributed to the abundant active electrocatalytic sites and enhanced interfacial charge-transfer by the well-organized surface structure.

Herein, sponge-like bismuthoxychloride (BiOCl) and hematite iron oxide (α-Fe2O3) were synthesized by simple and inexpensive method via two-step process, including hydrothermal and solution combustion method. The BiOCl/α-Fe2O3 composite photocatalysts were prepared by incorporating various weight ratios of α-Fe2O3 on BiOCl by a low-cost wet chemical process. The chemical interaction, phase and crystalline nature of the samples were ascertained by Fourier transform infrared spectroscopy (FT-IR) and x-ray diffraction (XRD). Further, the surface morphology and optical properties of the fabricated materials was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–vis diffuse reflection spectroscopy (DRS). Photocatalytic activities of the fabricated samples towards the photocatalytic degradation of direct red 81 (DR81) was evaluated under ultraviolet light illumination. The BiOCl/α-Fe2O3 composites showed remarkably enhanced photo-induced catalytic performances. The photocatalyst with optimal content of α-Fe2O3 with the highest photocatalytic performance was observed to 1%-BiOCl/α-Fe2O3. The synergistic improvement in the photodegradation of BiOCl/α-Fe2O3 sample may be because of an expansion in the noticeable light absorption efficiency as well as fast photo-generated charge separation. A probable mechanism for the photocatalytic degradation has been proposed for the catalytic performance of BiOCl/α-Fe2O3 photocatalyst. Keywords: Bismuthoxychloride, Direct red 81, Iron oxide, Photocatalysis, Photodegradation

Zinc oxide (ZnO) is an adaptable material that has distinctive properties, such as high-sensitivity, large specific area, non-toxicity, good compatibility and a high isoelectric point, which favours it to be considered with a few exceptions. It is the most desirable group of nanostructure as far as both structure and properties. The unique and tuneable properties of nanostructured ZnO shows excellent stability in chemically as well as thermally stable n-type semiconducting material with wide applications such as in luminescent material, supercapacitors, battery, solar cells, photocatalysis, biosensors, biomedical and biological applications in the form of bulk crystal, thin film and pellets. The nanosized materials exhibit higher dissolution rates as well as higher solubility when compared to the bulk materials. This review significantly focused on the current improvement in ZnO-based nanomaterials/composites/doped materials for the application in the field of energy storage and conversion devices and biological applications. Special deliberation has been paid on supercapacitors, Li-ion batteries, dye-sensitized solar cells, photocatalysis, biosensors, biomedical and biological applications. Finally, the benefits of ZnO-based materials for the utilizations in the field of energy and biological sciences are moreover consistently analysed.

The electrochemical behavior of 5-(4-Dimethylamino-benylidene)-1,3-diethyl-2-thioxo-dihydro-pyrimidine-4,6-dione at a plat-inum electrode was studied by semi-integration, semi differentiation of current, and digital simulation methods in 0.1 mol/L tetra-ethylammonium perchlorate (TEACl) in acetonitrile solvent. Cyclic voltammetric study revealed that the presence of three oxidative peaks due to the presence of two electron transfer coupled by chemical reaction (EC) and followed by electron transfer (E) step then EC, i.e., the overall process is ECEEC scheme. On going to negative potential there are two unidirectional reductive peaks associated with the oxida-tive peaks. The elucidation of the electrode behavior, the electrochemical and chemical data of the compound under investigation was de-termined using sweep voltammetry, semi integration & semi differentiation of current. The calculated electrochemical parameters and the nature of the electrode reaction were established & confirmed via generation of the theoretical cyclic voltammograms.