Photosensitive oxide semiconductors for solar hydrogen fuel and water disinfection

Abstract

Hydrogen is expected to become a commonly used energy carrier on the global scale in the near future. However, hydrogen as a fuel is environmentally friendly only when generated from water using renewable energy, such as solar energy. Therefore, intensive research aims to develop a new generation of solar materials, which may be used for the production of hydrogen fuel from water using solar energy. The highly promising candidates for solar energy conversion are photosensitive oxide semiconductors (POSs), particularly the TiO 2 -based semiconductors, which may be used for converting solar energy into the chemical energy required for hydrogen generation from water, as well as water purification (removal of microbial agents and toxic contaminants from water). The present work considers an R&D strategy for developing TiO 2 -based systems capable of converting solar energy into the chemical energy via water oxidation. The effect of surface versus bulk semiconducting properties on the performance of POSs is considered in terms of partial and total water oxidation. The progress requires modification of the key performance-related properties (KPPs) in order to enhance the light-induced reactivity of the POSs with water. The most recent approach in the development of POSs with enhanced performance is deposition of metallic islets of different size and shape in order to induce a plasmonic effect. The development of high-performance POSs can be achieved through a multidisciplinary approach. It is shown that defect disorder has a critical effect on the lightinduced reactivity of POSs and the solar energy conversion. Therefore, defect engineering may be applied in the development of high-performance POSs. This work considers the hurdles in the development of high-performance POSs for specific applications and formulates the key questions that must be addressed to overcome these hurdles. The concepts developed for TiO 2 may be expanded for other metal oxides. AbbreviationsAES Auger electron spectrometry EC Electrical conductivity ECE Energy conversion efficiency EMF Electromotive force ERDA Elastic coil detection analysis FBP Flat band potential IPHE International partnership for hydrogen economy KPP Key performance-related property LEED Low energy electron diffraction LEIS Low energy ion scattering spectroscopy LSPR Localised surface plasmon resonance NRA Nuclear reaction analysis PALS Positron annihilation lifetime spectroscopy PEC Photoelectrochemical cell PIXE Particle-induced X-ray emission POS Photosensitive oxide semiconductor PSP Propagating surface plasmon PV Photovoltaic RBS Rutherford backscattering SES Sustainable energy systems SIMS Secondary ion mass spectrometry

Defect chemistry and defect engineering of TiO2-based semiconductors for solar energy conversion

“…[1][2][3][4][46][47][48] Research is focused on the formation of a photoanode, which is based on TiO 2 semiconductors. [1][2][3][4][46][47][48] Research is focused on the formation of a photoanode, which is based on TiO 2 semiconductors.…”

Nanostructured Semiconductor Materials for Dye-Sensitized Solar Cells

“…In the recent past, there has been a crescent interest towards the development and the realization of solar radiation conversion devices in which an electrochemical process of reduction is photoactivated via the absorption of light by a cathode either in the pristine [233][234][235][236][237] or in a modified/sensitized state . These devices are photoelectrochemical cells (PECs) [40,87] with photoactive cathodes consisting of -type semiconducting materials and include -type dye-sensitized solar cells ( -DSCs) ( Figure 6) [242,243,247,248,264] and tandem DSCs (t-DSCs) (Figure 7) [ [265][266][267][268][269] cells of photoelectrolysis for nonfossil fuels production, namely, molecular H 2 in the process of water splitting (Figure 8) [270][271][272][273][274][275][276][277][278][279][280][281] and for carbon dioxide redox reduction (Figure 9) . The initial charge separation produced as a consequence of light absorption [312,313] can occur either directly on the -type semiconductor (Figure 9) or on the electrically connected sensitizer which accomplishes successively the transfer of charge according to the vectoriality imparted by the relative positions of the energy levels of the electronic states involved and by the kinetics of the possible redox reactions (Figures 6-8).…”

Multifunctional metal and metal oxide hybrid nanomaterials for solar light photocatalyst and antibacterial applications

“…In particular, photocatalysts capable of utilizing naturally abundant solar energetic spectrum were of interest for elimination of airborne and water-soluble chemical pollution [16][17][18][19][20][21]. Moreover, the potent antibacterial function could allow for fight against broad range of microbial organisms in unclean water such as Escherichia coli and Staphylococcus aureus [22][23][24][25][26].…”

“…For a specific application in photocatalysis, as light is harvested by photocatalysts, photons are captured from the energy source, steering electron excitation from valence to conduction bands [16][17][18][19][20][21]. The generated electrons and holes made possible for reductive and oxidative transformations of organic contaminants into carbon dioxide and water.…”