Graphene/Metal Oxide Nanocomposite Usage as Photoanode in Dye-Sensitized and Perovskite Solar Cells

Global energy shortage will be one of the most critical challenges in the next 50 years. Currently, over 80% of energy consumed is produced from fossil fuels, which is directly linked to global warming and environmental pollution issues. Environment-friendly renewable energy is rapidly gaining importance for the existence of human civilization. A leading source of renewable energy is the solar energy, which is inexhaustible and abundantly available. Solar cells that convert solar energy directly into electricity are drawing considerable attention as a potential turnkey solution to address these challenges. Several approaches have been made in this respect, including the development of better materials and the designs of new solar cell configuration and architecture. Among the innovative materials with potential application in emerging 3G solar cells, graphene and its derivatives such as GO, rGO and G/nanocomposite have been widely explored as transparent conducting electrodes, electron donor or acceptor materials and counter electrodes (CE). In this chapter, the use of graphene nanocomposites has been explored as an electrode material in DSSCs and PSCs. Recently, graphene/metal oxide nanocomposites have been widely used in DSSCs and PSCs and played a significant role in increasing charge transport, reducing charge recombination and thus enhancing the performance of solar cell

Visible light driven photoanodes for water oxidation based on novel r-GO/\u3b2-Cu2V2O7/TiO2 nanorods composites

This paper describes the preparation and the photoelectrochemical performances of visible light driven photoanodes based on novel r-GO/-Cu2V2O7/TiO2 nanorods/composites. -Cu2V2O7 was deposited on both fluorine doped tin oxide (FTO) and TiO2 nanorods (NRs)/FTO by a fast and convenient Aerosol Assisted Spray Pyrolysis (AASP) procedure. Ethylenediamine (EN), ammonia and citric acid (CA) were tested as ligands for Cu2+ ions in the aerosol precursors solution. The best-performing deposits, in terms of photocurrent density, were obtained when NH3 was used as ligand. When -Cu2V2O7 was deposited on the TiO2 NRs a good improvement in the durability of the photoanode was obtained, compared with pure -Cu2V2O7 on FTO. A further remarkable improvement in durability and photocurrent density was obtained upon addition, by electrophoretic deposition, of reduced graphene oxide (r-GO) flakes on the -Cu2V2O7/TiO2 composite material. The samples were characterized by X-ray Photoelectron Spectroscopy (XPS), Raman, High Resolution Transmission Electron Microscopy (HR-TEM), Scanning Electron Microscopy (SEM), Wide Angle X-ray Diffraction (WAXD) and UV\u2013Vis spectroscopies. The photoelectrochemical (PEC) performances of -Cu2V2O7 on FTO, -Cu2V2O7/TiO2 and r-GO/-Cu2V2O7/TiO2 were tested in visible light by linear voltammetry and Electrochemical Impedance Spectroscopy (EIS) measurements

Nanostructured Hybrid Materials Based On Reduced Graphene Oxide For Solar Energy Conversion

Research on carbon-based photocatalytic nanomaterials has been a field in continuous expansion in the last years. Graphene (or its derivatives) is currently one of the most studied materials due to its high surface area, photodegradation resistance, optical transparency and high charge mobility values. All of these excellent properties are highlighted for applications in various research areas. The incorporation of small amounts of reduced graphene oxide (RGO) sheets in semiconductors matrices is also a strategy widely used to improve the physicochemical properties, which cannot normally be achieved using conventional composites or pristine semiconductors. Most studies suggest that these two-dimensional (2D) materials can facilitate electron injection and assist the electron transport in semiconductors. In this context, this manuscript will present examples of graphene-based semiconductor nanocomposites obtained by our research group and their application in the photodegradation of methylene blue (MB), photocatalytic conversion of CO2 to hydrocarbon fuels and photocatalytic water splitting reaction. Our results show the positive effect of coupling the RGO sheets with semiconductors for photocatalysis.9923Conference on Physical Chemistry of Interfaces and Nanomaterials XVAUG 28-31, 2016San Diego, C

Counter electrode materials based on carbon nanotubes for dye-sensitized solar cells

Efficiency, stability, and cost-effectiveness are the prime challenges in research of materials for solar cells. Technologically as well as scientifically, attention gained by dye-sensitized solar cells (DSSCs) stems from their low material and fabrication costs as well as high efficiency projections. The aim of this study is to explore the carbon nanotubes (CNTs) based counter electrode (CE) materials for DSSCs and to reconnoiter the suitable alternative materials in place of noble metals such as Platinum (Pt), and Gold (Au).. Various classes of CE materials based on CNTs including pure single walled, double walled, and multiwalled CNTs, doped CNTs and their hybrid composites with various polymers, and transition metal compounds are discussed comprehensively in light of the research work started since the inspection of DSSCs and CNTs.The properties associated with such materials, including surface morphology, structural determination, thermal stability, and electrochemical activity, are also thoroughly analyzed and compared. This work provides a thorough insight into the possibility of exploiting CNTs as alternative CE materials. In addition to the above, this study also includes the working and brief overview of materials for other components of DSSCs such as photoanode, electrolyte, and sensitizer.

Engineering of magnetically separable ZnFe2O4@ TiO2 nanofibers for dye-sensitized solar cells and removal of pollutant from water

Abstract In this study, magnetic Zinc Ferrite (ZnFe2O4)@TiO2 nanofibers were prepared by low cost and nontoxic route; hydrothermal technique followed by electrospinning process. The prepared magnetic ZnFe2O4@TiO2 nanofibers were morphologically and structurally analyzed by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), and thermal gravimetric analysis (TGA). The prepared magnetic ZnFe2O4@TiO2 nanofibers were utilized as photoanode for the fabrication of dye-sensitized solar cells (DSSCs) and presented applicable performance with 4.2% overall conversion efficiency with high short circuit current density (JSC) of 10.16 mA/cm2. The maximum ∼42% incident photo-to-current conversion efficiency (IPCE) value was also recorded at 520 nm. In addition, ZnFe2O4@TiO2 nanofibers were not only possessed the good conversion efficiency, but also shown excellent photocatalytic efficiency with magnetic properties towards the dye remediation. Prepared ZnFe2O4@TiO2 nanofibers can be considered as a promising material for energy conversion and environmental applications

Bench-scale photoelectrocatalytic reactor utilizing rGO-TiO2 photoanodes for the degradation of contaminants of emerging concern in water

Pharmaceuticals and personal care products are contaminants of emerging concern (CEC) in water. Photocatalysis (PC) and photoelectrocatalysis (PEC) are potential advanced oxidation processes for the effective degradation of these contaminants. In this work a bench-scale photoelectrocatalytic reactor utilizing a UVA-LED array was designed and tested for the degradation of diclofenac as a model CEC. Reduced graphene oxide-titanium dioxide (rGO-TiO2) composite, prepared by the photocatalytic reduction of rGO on TiO2, was immobilised on fluorine doped tin oxide (FTO) glass and evaluated as a photoanode. The influence of UVA intensity and rGO:TiO2 ratio on the degradation rate was studied. Surface modification of the TiO2 with 1% rGO gave the highest photocurrent and best degradation rate of diclofenac, as compared to unmodified TiO2. However, following repeat cycles of photoelectrocatalytic treatment there was an observed drop in the photocurrent with rGO-TiO2 anodes and the rate of diclofenac degradation decreased. Raman and XPS analysis indicated the re-oxidation of the rGO. Attempts to regenerate the rGO in-situ by electrochemical reduction did not prove successful, suggesting that the site of photoelectrocatalytic oxidation of rGO was different to the reduction site targeted in the photocatalytic reduction for the formation of the rGO-TiO2 composites

Investigation of TiO2/graphene nanocomposite based photoanode in dye-sensitized solar cell

Dye-Sensitized Solar Cell (DSSC) which is the third generation photovoltaic solar cell is a promising low cost solar cell. This type of solar cell is robust and do not require clean environment for fabrication. This paper focuses on implementation of graphene in the DSSC photoanode to improve the electron path from photoanode to FTO transparent electrode. In this research, N719 synthetic dye is used as synthesizer and three different types of graphene nanopowder namely 8 nm flakes, multilayer flakes and nanoplatelets were implemented in titanium dioxide as photo-anode. I-V measurement was done under illumination of 1000 W/m2 using solar simulator and the results show that the DSSC with titanium dioxide photoanode doped with graphene multilayer flakes performs the best in term of open circuit voltage (0.782 V), short circuit current density (12.408 mA/cm2) and energy conversion efficiency (4.4%)

Nanostructured Transition Metal Oxides for Energy Storage and Conversion

The conventional film configuration of electrochemical electrodes hardly fulfills the high energy and efficiency requirements because heavy electroactive material deposition restricts ion diffusion path, and lowers power density and fault tolerance. In this thesis, I demonstrate that novel nanoarchitectured transition metal oxides (TMOs), e.g. MnO2, V2O5, and ZnO, and their relevant nanocomposites were designed, fabricated and assembled into devices to deliver superior electrochemical performances such as high energy and power densities, and rate capacity. These improvements could be attributed to the significant enhancement of surface area, shortened ion diffusion distances and facile penetration of electrolyte solution into open structures of networks. The utilization of Forcespinning® , a newly developed nanofiber processing technology, for large-scale energy storage and conversion applications is emphasized. This process facilitates the contradiction between the micro-batch production and the ease of large-scale manufacturing