Photocatalytic Solar Cell Research Articles

Zirconium-based cubic-perovskite materials for photocatalytic solar cell applications: a DFT study.

The structural, electronic, optical, and mechanical characteristics of the cubic inorganic perovskites XZrO3 (X = Rb and K) based on Rb and K were studied using Cambridge Serial Total Energy Package (CASTEP)-based density functional theory (DFT) via the ultrasoft pseudo-potential (USP) plane wave and generalized gradient approximation (GGA)-Perdew–Burke–Ernzerhof (PBE) exchange–correlation functional. The measured lattice parameters are 3.55 Å and 4.23 Å, and the band gaps of RbZrO3 and KZrO3 are 3.57 eV and 3.78 eV, respectively. Our results indicate that the compounds have indirect and wide bandgaps, making them useful for improving conductivity. It is observed that the compounds have anisotropic, ductile, and brittle natures. The anisotropic factor values of RbZrO3 and KZrO3 are 0.67067 and 0.87224, and their Poisson's ratios are 0.27356 and 0.25853, respectively. In terms of optical properties, they exhibited high optical absorption and conductivity and were active in the visible region for solar cell applications. These results indicate that they could be highly useful for light-emitting diodes (LEDs) and other reflection purposes owing to their indirect bandgap. The results of our investigation of RbZrO3 and KZrO3 present them as favorable materials for solar cell and LED applications.

Distinct Binding of Rhenium Catalysts on Nanostructured and Single-Crystalline TiO2 Surfaces Revealed by Two-Dimensional Sum Frequency Generation Spectroscopy

High surface area TiO2 electrodes are extensively used in photocatalytic solar cells. However, it remains controversial how molecular catalysts interact with the TiO2 surfaces and how the electrodes affect the functionality of catalytic adsorbates. Here, we examine the CO2 reduction catalyst ReI(dcbpy)(CO)3Cl (dcbpy = 4,4′-dicarboxy-2,2′-bipyridine) on TiO2 by probing spectroscopically isolated carbonyl modes that are highly sensitive to the complex electronic structure and solvation environment. Combining interferometric two-dimensional sum frequency generation spectroscopy and ab initio simulations of the spectra, we find distinct spectroscopic and dynamical properties of catalysts bound to single crystals and nanocrystalline surfaces. Different cross-peak patterns resulting from interferences between elements of the fourth-order susceptibility, along with different vibrational relaxation dynamics, reveal distinct vibrational relaxation pathways of the catalysts on different TiO2 surfaces that could be ...

Initial Phase of Photoelectrochemical Conditioning of Silicon in Alkaline Media: Surface Chemistry and Topography

Oxidation and dissolution phenomena of Si(111) in alkaline electrolyte are investigated by a combination of photoelectrochemistry, scanning probe microscopy (SPM), transmission electron microscopy (TEM) and in-system synchrotron radiation photoelectron spectroscopy (SRPES). The surface topography in the initial anodic potential regime shows the formation of mesoscale pores with widths in the range 300–500 nm and partial surface oxidation. The surface chemistry assessment by SRPES shows patchy silicon oxide growth, suboxides, and remnants of the former hydrogen terminated surface areas. The use of the obtained self-organized nanostructures for application in nanoemitter photocatalytic solar cells is discussed. The necessary requirements regarding the total surface area of electrocatalysts needed to sustain the current density due to light-induced excess minority carriers in conjunction with the exchange current density of the considered heterogeneous catalysts is discussed.

Deposition of an oxomanganese water oxidation catalyst on TiO2 nanoparticles: computational modeling, assembly and characterization

Inexpensive water oxidation catalysts are needed to develop photocatalytic solar cells that mimic photosynthesis and produce fuel from sunlight and water. This paper reports the successful attachment of a dinuclear di-µ-oxo manganese water oxidation catalyst [H2O(terpy)MnIII(µ-O)2 MnIV(terpy)H2O](NO3)3 (1, terpy = 2,2′:6′2″-terpyridine) onto TiO2 nanoparticles (NPs) via direct adsorption, or in situ synthesis. The resulting surface complexes are characterized by EPR and UV-visible spectroscopy, electrochemical measurements and computational modeling. We conclude that the mixed-valence (III,IV) state of 1 attaches to near-amorphous TiO2 NPs by substituting one of its water ligands by the TiO2 NP, as suggested by low-temperature (7 K) EPR data. In contrast, the analogous attachment onto well-crystallized TiO2 NPs leads to dimerization of 1 forming Mn(IV) tetramers on the TiO2 surface as suggested by EPR spectroscopy and electrochemical studies.