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SnS2 nanoflakes substituted with different concentrations of Co (1, 3 and 5 %) have been synthesized by the hydrothermal process using SnCl4·5H2O, CH4N2S and Co(NO3)2.6H2O. The effect of Co on SnS2 nanoflakes were characterized by diverse analytical methods such as Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman and X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and current voltage (I–V) measurement. The XRD of pristine and Co substituted SnS2 shows a hexagonal berndtite crystal structure. The FESEM image reveals the morphology of layered nanoflakes. Elemental composition and binding state of element were studied using XPS. The Co substitution influences the SnS2 nanoflakes morphology, electrochemical and photovoltaic performance of the devices. The promising power conversion efficiency of 2.56 % was obtained with 3 % Co substituted SnS2 nanoflakes which is suitable for low-cost dye sensitized solar cells.

Alteration of the optical and photoelectrical properties of the photoanode materials are a prerequisite for improving the performance of dye-sensitized solar cell (DSSC). In this work, Ag-decorated cauliflower-like TiO2 photoanode was fabricated and studied the photovoltaic performance. The hierarchical structured TiO2 with abundant bundles exhibited a novel matrix for Ag deposition by the photoreduction technique. It is significant that the Ag nanoparticles showed a uniform size distribution on hierarchical structured TiO2 nanorods (HNRs). The plasmonic particle enfolded photoanode-based DSSC exhibited an efficiency of 4.15%, which is higher compared to the pristine TiO2 HNR (3.83%). The progress in the efficiency of plasmon particle-based DSSC is crucial, regarding the optical properties, and reduced charge transport resistance observed from the UV visible analysis (UV-Vis) and electrochemical impedance spectra (EIS).

In this study, novel Gadolinium doped WO3 nanorods (Gd@WO3 NRs) were synthesized via facile hydrothermal method. The Gd@WO3 NRs were systematically characterized by XRD, RAMAN, FESEM, XPS, UV–Vis, and PL. XRD profiles confirmed the single phase of WO3, and the average crystallite size decreased with increasing the doping concentration. From EDS and XPS analysis of Gd@WO3 NRs, the presence of Gd, W, and O were confirmed without any additional peaks. UV–Vis spectra indicated that the position of the absorption edge lies within the visible region at all Gd contents in WO3, and the energy gap was studied. The photoluminescence test indicates that the 5 wt% of Gd doping in WO3 could reduce the photogenerated electron-hole pair recombination. The remarkable enhancement in the photodegradation activity for degrading the Rhodamine B under visible-light irradiation of WO3 was studied with Gd doping. The highest photocatalytic performance was found with 5 wt% Gd@WO3 NRs, due to the accelerated charge transfer process, which improved the photogenerated electron-hole pairs separation. According to trapping studies, the possible photocatalytic mechanism of Gd@WO3 NRs was also disclosed. The recycling test confirmed the stability of photocatalyst after three cycles. This novel Gd@WO3 NRs proved to be a superior catalyst for the reduction of organic pollutants.

Herein, WO3 nanorods have been prepared by simple hydrothermal method with the assistance of Na2SO4 as a structure-directing agent (SDA). The impact of SDA concentrations on the structural, morphological, optical, and photocatalytic performance of WO3 nanoparticles has been investigated. From XRD pattern, the phase transformation (monoclinic to hexagonal) was observed after adding SDA into WO3 matrix. Randomly oriented hexagonal WO3 nanorods were developed by the influence of SDA, which has been observed with FE-SEM analysis. The chemical composition and electronic structure of hexagonal WO3 nanorods photocatalyst were confirmed by X-ray photoelectron spectroscopy. The blue shift absorbance was recorded in UV–Vis spectrum. In the PL spectrum, the surface oxygen vacancy or defects were obtained at a wavelength of 520 and 552 nm. Also, the influence of defects in the WO3 nanorods facilitates to improve the photocatalytic dye degradation performance. The hexagonal WO3 nanorods prepared at 0.05 m of SDA exhibit maximum degradation efficiency of 86% under visible light exposure. Furthermore, the specific catalyst showed an excellent stability and reusability up to four consecutive cycles of photocatalytic dye degradation.

Enhancing the conductivity of polymer electrolytes in DSSC has evolved as an important strategy to enhance the efficiency of the DSSC. In this context, we have synthesized a range of graphene based derivatives which when incorporated into a polymer electrolyte enhances the ionic conductivity of PEO/PVDF-HFP polymer electrolyte by 30 times reaching a maximum value of 3.07 × 10−4 S/cm. Devices fabricated from these modified solid state electrolyte exhibited a photo-conversion efficiency of upto 4.24% which is comparable to the efficiency magnitude observed in liquid electrolyte based DSSC fabricated under similar condition at our laboratory. Detailed structural, microscopic and morphological characterization attributed this enhancement in the electrochemical performance to a combination of factors such as reduced crystallinity of the polymer electrolyte membrane, development of smooth non-porous structure and increased chemical interaction between the lamellar structure.

The proposed work suggests the fabrication of hybrid TiO2/reduced graphene oxide composites with self-assembled multidimensional structure. The two step facile alkaline hydrothermal route is implemented using variable wt% of GO for the successful synthesis of multidimensional reduced graphene oxide TiO2 composites structure (MGTS). In the first step, TiO2 aggregates (TNA) were prepared by low temperature hydrothermal process. Subsequently, growth of multidimensional TiO2 on hGO sheet, as well as simultaneous reduction of GO is done and the as prepared MGTS is applied for dye sensitized solar cell (DSSC). Structural and surface morphology of the developed samples were investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. The X-ray photoelectron spectroscopy studies monitored the chemical composition and surface binding energy of TNA and MGTS samples. The current-voltage (J-V) and electrochemical impedance studies evaluates the performance of the TNA and MGTSs photoanodes in DSSC. The finest loading of GO in the TiO2 matrix assisted the accelerated electron transport channel within the TiO2 matrix resulting in superior photo conversion efficiency of 8.62% as compared with neat TiO2 which has an efficiency of 6.3%.

Fe2O3 was synthesized by chemical precipitation method and used as filler in PVDF-HFP based polymer electrolyte for dye sensitized solar cell (DSSC) applications. The plasticized polymer membrane was developed by simple solution casting method with incorporation of Fe2O3 where propylene carbonate was used as plasticizing agent. Structural confirmation of synthesized Fe2O3 powder and crystallinity studies prepared polymer membrane with different weight% of Fe2O3 was studied by the X-ray diffraction analysis. Fourier transform infrared studies of polymer membrane are done to study nature of polymer. Fe2O3 incorporated PVDF-HFP based polymer electrolyte showed ionic conductivity of 6.36 × 10−4 S/cm and diffusion coefficient was found to be 1.02 × 10−6 cm2/s. Furthermore, the electrochemical impedance spectroscopy analysis has been done to study interfacial resistance. The prepared polymer electrolyte (2 wt% filler in PVDF-HFP based) was used in DSSC fabrication, where calculated power conversion efficiency was 3.62% with the enhancement of 2.1 times when compared to pure PVDF-HFP electrolyte. The photocurrent stability of the device under several light on-off cycles is proved via chronoamperometry study. In addition, variation of power conversion efficiencies as a function of time has also been analyzed.

A green approach to synthesize three dimensional pyramid structured ZnO and Ag decorated ZnO nanoparticles were developed by one pot hydrothermal method and they were successfully applied as photoanode for DSSC. Neem extract was utilized to control the size of Ag particles. The structural and morphological properties of synthesized samples of ZnO and Ag-ZnO nanocomposites have been investigated by XRD, FESEM, and HRTEM analysis respectively. The XPS studies were performed for scrutinizing the binding energy of ZnO and Ag-ZnO nanostructured materials. The UV–VIS absorption spectrum of Ag-ZnO nanostructure displaced absorption towards visible region than the pristine ZnO. The electrochemical properties of both ZnO and Ag-ZnO nanostructure were studied using EIS (Electrochemical impedance spectra). The photoconversion efficiency of Ag-ZnO based DSSC cell showed an efficiency of 3.51% which has higher conversion efficiency than pristine ZnO (2.62%).

In the current investigation, TiO2 and TiO2-ZnO (core-shell) spherical nanoparticles were synthesized by simple combined hydrolysis and refluxing method. A TiO2 core nanomaterial on the shell material of ZnO was synthesized by utilizing variable ratios of ZnO. The structural characterization of TiO2-ZnO core/shell nanoparticles were done by XRD analysis. The spherical structured morphology of the TiO2-ZnO has been confirmed through field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) studies. The UV–visible spectra of TiO2-ZnO nanostructures were also compared with the pristine TiO2 to investigate the shift of wavelength. The TiO2-ZnO core/shell nanoparticles at the interface efficiently collect the photogenarated electrons from ZnO and also ZnO act a barrier for reduced charge recombination of electrolyte and dye-nanoparticles interface. This combination improved the light absorption which induced the charge transfer ability and dye loading capacity of core-shell nanoparticles. An enhancement in the short circuit current (Jsc) from 1.67 mA/cm2 to 2.1 mA/cm2 has been observed for TiO2-ZnObased photoanode (with platinum free counter electrode), promises an improvement in the energy conversion efficiency by 57% in comparison with that of the DSSCs based on the pristine TiO2. Henceforth, TiO2-ZnO photoelectrode in ZnO will effectively act as barrier at the interface of TiO2-ZnO and TiO2, ensuring the potential for DSSC application.

Exploring highly efficient visible-light-driven photocatalyst for the elimination organic pollutants is a great concern for constructing sustainable green energy systems. In the current work, a novel hybrid ternary WO3@g-C3N4@MWCNT nanocomposites have been fabricated for visible-light-driven photocatalyst by self-assembly method. The as-prepared photocatalyst was examined by XRD, Raman, FESEM, HRTEM, XPS EDS, EIS, UV–visible DRS, and PL analysis. The experimental results revealed that the photocatalytic activity of WO3@g-C3N4@MWCNT nanocomposites on the degradation of Tetracycline (TC) is 79.54% at 120 min, which is higher than the binary WO3@g-C3N4 composite and pristine WO3. The improved degradation performance towards TC is recognized for its higher surface area, intense light absorption towards the visible region, and enhanced charge separation efficiency. Consequently, the fabricated catalyst endows a promising application for antibiotic degradation.

In this Work, Ce doped WO3 nanorods have been prepared by a simple hydrothermal method. Ce@WO3 samples exhibit excellent photocatalytic performance towards Rhodamine B(RhB) dye degradation, better than pristine WO3 NRs. XRD and Raman's spectroscopy confirm that no new peak was absorbed after Ce's addition into WO3 and retained its hexagonal phase. X-ray photoelectron spectroscopy (XPS) examined the chemical composition and the surface binding energy of the Ce@WO3 catalyst. The redshift in the absorption spectra indicates the increment of oxygen vacancies in the WO3 surface. The lowest PL intensity of 3% Ce@WO3 catalyst could slow the charge carrier's recombination, enhancing the photocatalytic performance. The 3% Ce@WO3 sample exhibits excellent photodegradation efficiency (96%) under visible light irradiation for 100 mins with a rate constant (3.18447 × 10−2 min−1). The recycling test indicates the stability of the catalyst. These results suggest that Ce@WO3 nanorods were the superior catalyst for wastewater treatment.

This proposed work suggests the fabrication of hybrid WO3/reduced graphene oxide (WRG) composites with rod-like structures through the facile hydrothermal method. The WO3 nanorod has been grown on the GO sheet, concurrent reduction of GO has been made, and the as-prepared WRG is employed as photocatalyst. The fabricated samples structural and morphological properties were scrutinized by X-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM). The chemical composition and surface binding energy were monitored by using X-ray photoelectron spectroscopy (XPS). The WRG composites exhibited excellent photocatalytic activity for decomposing organic dye Rhodamine B (RhB) & antibiotic pollutants like Ciprofloxacin (CIP) under visible light irradiation. The adequate loading of GO on WO3 matrix reduced the charge carrier's recombination and enhanced the degradation performance. Hybrid photocatalyst exhibit higher rate constant values; 2.76 × 10−2 min−1 and 2.07 × 10−2 min−1 for RhB and CIP pollutants, respectively.

The utilization of solar energy by virtue of which, an economically viable, steady and sustainable device fabrication are the need for future generation. In this regard, the replacement of platinum (Pt) free counter electrode (CE) in dye sensitized solar cell (DSSC) is probed for widespread application. In this study, our aim is to improve the ability of charge transfer as well as to increase the active site with the enrichment of catalytic activity of CEs. NiCo2O4 decorated reduced graphene oxide (NCG) sheets were synthesized by chemical precipitation route and subsequently polymerized with aniline for NCG-polyaniline (PANI) complex for efficient CEs in DSSC. The prepared CE significantly amplifies the charge transfer capability of ternary complex and it is reflected for the proficient reduction towards I-/I3 redox shuttles. The fabricated CE (NCG-PANI) yield maximum photo-to-electron conversion efficiency of 4.67% which is higher than NCG based DSSC (4.1%). The study suggests that NiCo2O4/rGO/PANI (NCG-PANI) CEs with higher electrocatalytic performance and efficient charge transfer activity prepared by cost effective technique could be potential for Pt-free DSSC applications.