The photocatalytic splitting of water into hydrogen and oxygen using solar energy is a potentially clean and renewable source for hydrogen fuel. The first photocatalysts suitable for water splitting, or for activating hydrogen production from carbohydrate compounds made by plants from water and carbon dioxide, were developed several decades ago. But these catalysts operate with ultraviolet light, which accounts for only 4% of the incoming solar energy and thus renders the overall process impractical. For this reason, considerable efforts have been invested in developing photocatalysts capable of using the less energetic but more abundant visible light, which accounts for about 43% of the incoming solar energy. However, systems that are sufficiently stable and efficient for practical use have not yet been realized. Here we show that doping of indium-tantalum-oxide with nickel yields a series of photocatalysts, In(1-x)Ni(x)TaO(4) (x = 0-0.2), which induces direct splitting of water into stoichiometric amounts of oxygen and hydrogen under visible light irradiation with a quantum yield of about 0.66%. Our findings suggest that the use of solar energy for photocatalytic water splitting might provide a viable source for 'clean' hydrogen fuel, once the catalytic efficiency of the semiconductor system has been improved by increasing its surface area and suitable modifications of the surface sites.
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"Honda and Fujishima, pioneers in photocatalytic generation of H 2 , investigated photo-electrochemical H 2 generation through use of TiO 2 electrode. Latter revolutionary works were carried out in the field of photocatalysis by various leading research groups4567. Significant part of this endeavor is dedicated to air/water purification891011. "
[Show abstract][Hide abstract] ABSTRACT: TiO2 is indeed one of the widely used semiconductors employed for photocatalytic hydrogen production. Most of its photocatalytic activity is achieved in its crystalline form. However, its photocatalytic activity is limited to ultraviolet region. For making TiO2 visible light active; Au deposition is strongly recommended due to its surface plasmon feature. Au deposition enhances the photocatalytic activity of both crystalline and nanocrystalline TiO2. Efficiency of photocatalytic activity is controlled by shape and size of Au nanoparticle subsequently the synthetic methodology plays an important role.
Full-text · Article · May 2016 · Renewable and Sustainable Energy Reviews
[Show abstract][Hide abstract] ABSTRACT: Quantum dot sensitized photoanodes have drawn much attention due to their high potential as efficient anodes for photoelectrochemical (PEC) water splitting or solar cells. However the photocorrosion of QDs is the crucial barrier for applications in these devices. The in situ analysis of photocorrosion is important in understanding its mechanism and also developing the possible solution for photocorrosion. In this study we have developed a novel, integrated analysis system for in situ measurements of photocorrosion and PEC performances. We have fabricated the CdSe/CdS/ZnO nanowire (NW) arrays on quartz crystal microbalance (QCM) as a platform for usage as PEC photoanodes and also mass analysis at the same time. The in situ measuring of photocurrents and mass changes were performed with continuous operation of PEC cells for CdSe/CdS/ZnO NWs photoanode. The study exhibited highly correlated tendency in photocurrent decrease and mass reduction, due to photocorrosion of CdSe/CdS/ZnO NWs. Also to improve the photostability of CdSe/CdS/ZnO NWs, applications of passivation and catalysts were studied and their effects were discussed. Our integrated in situ analysis system is highly applicable to various semiconductor sensitized systems.
Full-text · Article · Dec 2015 · Sensors and Actuators B Chemical
"Over the past few years, various toxic and hazardous organic dyes, such as Rhodamine B, Methylene blue and Methyl orange, have caused severe environmental pollution via the effluent discharge generated from textile industry [23e25]. Most of them are resistant to biodegradation and may undergo natural reductive anaerobic degradation to yield potentially carcinogenic intermediates . The photocatalytic reaction has become a desirable method to transform the organic pollutants into nontoxic molecules to eliminate the environmental pollution. "
[Show abstract][Hide abstract] ABSTRACT: Dy3+ doped Mg2SiO4 nanoparticles have been synthesized by the solution combustion method at 350 °C temperature. The crystallinity and changes of lattice parameters with the incorporation of the Dy3+ ions are studied by means of Powder X-Ray Diffraction studies. Fourier transform infrared data indicate the formation of bonds and capping of the nanoparticles. Scanning electron microscopy pictures evident for the product is porous and agglomerated. The nano size of the product is confirmed by means of transmission electron microscopy. The characteristic emission peaks and the Judd–Ofelt intensity parameters of Mg2SiO4:Dy3+ nanoparticles are studied. The emission can be tuned from green (0.238, 0.348) to white (0.276, 0.347) which indicates, the prepared phosphors can be effectively used for white light emitting diodes and biosensors. Further, the degradation of dyes is found to be enhancing in the presence of Dy3+ ions due to suppress of the e−CB and h+VB recombination.
Full-text · Article · Dec 2015 · Dyes and Pigments