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Dye-sensitized TiO2 solar cells, DSSC, are a promising alternative for the development of a new generation of photovoltaic devices. DSSC are a successful combination of materials, consisting of a transparent electrode coated with a dye-sensitized mesoporous film of nanocrystalline particles of TiO2, an electrolyte containing a suitable redox-couple and a Pt coated counter-electrode. In general, Ru bipyridyl complexes are used as the dye sensitizers. The light-to-energy conversion performance of the cell depends on the relative energy levels of the semiconductor and dye and on the kinetics of the electron-transfer processes at the sensitized semiconductor | electrolyte interface. The rate of these processes depends on the properties of its components. This contribution presents a discussion on the influence of each of the materials which constitute the DSSC of the overall process for energy conversion. An overview of the results obtained for solid-state dye-sensitized TiO2 solar cells assembled with polymer electrolytes is also presented.

Cu2O, a photoactive p‐type semiconductor based on earth‐abundant elements, shows promising features for photoelectrochemical CO2 reduction reaction (PEC CO2RR). However, despite the broad light absorption and appropriate conduction band edge energy, it promptly undergoes photocorrosion in PEC CO2RR conditions. Herein, we evaluate an amine‐functionalized polysiloxane (AF−PSi) as both protective layer and PEC CO2RR promoter via amine‐CO2 adduct formation. Electrochemistry experiments and X‐ray diffraction showed that photostability is significantly enhanced with AF−PSi overlayer. Electrolyses experiments under visible light irradiation indicated selective production of formate with faradaic efficiency of 61 % at low overpotential. Detailed in situ FTIR studies revealed that amine groups bind to CO2 to form carbamate species and that this process is favoured by cathodic polarization, confirming the dual role of AF−PSi layer. [ABSTRACT FROM AUTHOR]

A solid‐state perspective is offered for a discussion of silver‐based ternary and quaternary oxide semiconductors for applications related to solar fuels photogeneration and environmental remediation. The rather unique d10 electron configuration in these compounds is shown to impart interesting effects on their optoelectronic properties, and in turn, the photocatalytic activity of these compounds. This Minireview focuses on the structural aspects, electronic band structures, synthetic advances, and finally photoelectrochemical and photocatalytic applications of 32 compounds within the two oxide families, of the generic formula: AgxByOz or AgxByCnOz, where B and C are metals or non‐metals other than silver. A solid‐state perspective is offered for a discussion of silver‐based ternary and quaternary oxide semiconductors for applications related to solar fuels photogeneration and environmental remediation. This Minireview focuses on the structural aspects, electronic band structures, synthetic advances, and photoelectrochemical and photocatalytic applications of compounds of the generic formula: AgxByOz or AgxByCnOz. [ABSTRACT FROM AUTHOR]

Solid-state rigid and flexible regenerative dye-sensitized TiO2 solar cells are assembled using a polymer electrolyte and glass-fluorine-doped tin oxide (FTO) or poly(ethylene terephthalate) coated with tin-doped indium oxide (PET-ITO) transparent electrodes as substrates. Electrochemical impedance spectroscopy was used to investigate the cells in the dark and under illumination. The general behavior of the spectra was similar for both cells, but the impedance of the flexible cell was higher than that of the rigid one.

Nanocrystalline TiO2 and reduced graphene oxide (TiO2/RGO) composite films were prepared by combining a sol–gel method with hydrothermal treatment, employing titanium isopropoxide (Ti(OiPr)4) and graphene oxide (GO) as starting materials. Although several reports in the literature have explored the benefits of RGO addition in titania films for photocatalysis and water splitting reactions, the role of RGO in the composite is always described as that of a material that is able to act as an electron acceptor and transport electrons more efficiently. However, in most of these reports, no clear evidence for this “role” is presented, and the main focus is deviated to the improved efficiency and not to the reasons for said efficiency. In this study, we employed several techniques to definitively present our understanding of the role of RGO in titania composite films. The TiO2/RGO composite films were characterized by X ray diffraction, Raman spectroscopy, microscopy and electrochemical techniques. In photoelectrochemical water splitting studies, the TiO2/RGO(0.1%) photoelectrodes showed the highest photocurrent density values (0.20 mA cm−2 at 1.23 VRHE) compared to other electrodes, with an increase of 78% in relation to pristine TiO2 film (0.11 mA cm−2 at 1.23 VRHE). The transient absorption spectroscopy (TAS) results indicated increases in the lifetime and yield of both the photogenerated holes and electrons. Interestingly, the TiO2/RGO(0.1%) film exhibited the best charge generation upon excitation, corroborating the photoelectrochemical data. We proposed that in films with lower concentrations (＜0.1 wt%), the RGO sheets are electron acceptors, and a decrease in the charge recombination processes is the immediate consequence. Thus, both holes and electrons live longer and contribute more effectively to the photocurrent density. [ABSTRACT FROM AUTHOR]