Nanostructured SnS with inherent anisotropic optical properties for high photoactivity

In view of the worldwide energy challenge in the 21(st) century, the technology of semiconductor-based photoelectrochemical (PEC) water splitting has received considerable attention as an alternative approach for solar energy harvesting and storage. Two-dimensional (2D) structures such as nanosheets have the potential to tap the solar energy by unlocking the functional properties at the nanoscale. Tin(ii) sulfide is a fascinating solar energy material due to its anisotropic material properties. In this manuscript, we report on exploiting the 2D structure modulated optical properties of nanocrystalline SnS thin film synthesized by chemical spray pyrolysis using ambient transport in the harvesting of solar energy. We obtained the nanostructured SnS with well-preserved dimensions and morphologies with one step processing. The work demonstrates that the intrinsically ordered SnS nanostructure on FTO coated glass can tap the incident radiation in an efficient manner. The structure-property relationship to explain the photo-response in nanocrystalline-SnS is verified experimentally and theoretically. The novel design scheme for antireflection coating along with the anisotropic properties of SnS is conceived for realizing a PEC cell. The developed PEC cell consists of a SnS photoanode which shows considerably high photocurrent density of 7 mA cm(-2) with aqueous media under AM 1.5G, 100 mW cm(-2) exposure with notably stable operation. Electrochemical impedance spectroscopy revealed that a non-ideal capacitive behavior as well as drift assisted transport across the solid-state interface is responsible for such a high photo-current density in the nanocrystalline-SnS photoanode.

One-step solvothermal synthesis of Fe-doped BiOI film with enhanced photocatalytic performance

Ultrathin nanosheets consisting of Fe-doped BiOI were obtained on a FTO (SnO₂:F) glass substrate via a simple solvothermal process.

Impedance analysis of inherently redox-active ionic-liquid-based photoelectrochemical cells: charge-transfer mechanism in the presence of an additional redox couple

An intensive electrochemical impedance study was carried out to understand the charge-transfer processes in photoelectrochemical (PEC) cells based on ionic liquid (IL) electrolytes. Three different electrolytes were utilized to understand the role of redox species as well as the medium on the charge-transfer mechanism. The negligible diffusion resistance, despite the presence of two different redox species in the case of Fe(CN)(6) (-4/-3) in IL, was explained on the basis of charge transfer between species of two different redox couples. Accordingly, the redox species are not required to travel through the bulk of the electrolyte for the removal of accumulated charges, as short-range charge transfer between the IL and the Fe(CN)(6) (-4/-3) species facilitates the removal of accumulated charges. It is also shown that PEC cells utilizing dual redox couples are highly stable with larger photoelectrochmeical windows, >3 V.

Unraveling the photoelectrochemical properties of ionic liquids: cognizance of partially reversible redox activity

Ionic liquid based electrolytes are gaining great interest in the field of photoenergy conversion. We have found that the ionic liquids namely BMIm Cl, BMIm PF6 and BMIm Tf2N inherently offer redox activity. The device performance of the photoelectrochemical (PEC) cells of the configuration PbOx (0.25 cm(2))|blank ionic liquids|platinum (2 cm(2)) was analyzed in detail to get insights into the working principle of such systems. It was found that partially reversible redox ion pairs diminish the performance of such cells as power generating devices. The partial redox activity of the ionic liquids was confirmed by a number of observations derived from the PEC spectra. The important parameter, Vredox, which determines the performance of any PEC cell was also calculated for all the ionic liquids. The difficulties that arise in high frequency C-V measurements for ionic liquid systems were overcome by choosing the appropriate probing frequency. The evaluated Vredox of BMIm Cl, BMIm PF6 and BMIm Tf2N ionic liquids was found to be -0.30, -0.20 and -0.78 V (vs. NHE), respectively. This study will be beneficial to understand the role of ionic liquids as redox active electrolyte media in several applications.

Reduced graphene oxide–ZnO self-assembled films: tailoring the visible light photoconductivity by the intrinsic defect states in ZnO

ZnO is a wide direct bandgap semiconductor; its absorption can be tuned to the visible spectral region by controlling the intrinsic defect levels.