Splitting image: Sustainable hydrogen production is a key target for the development of alternative, future energy systems that will provide a clean and affordable energy supply. This Minireview focuses on the development of semiconductor catalysts that enable hydrogen production via water splitting upon visible-light irradiation.
Sustainable hydrogen production is a key target for the development of alternative, future energy systems that will provide a clean and affordable energy supply. The Sun is a source of silent and precious energy that is distributed fairly all over the Earth daily. However, its tremendous potential as a clean, safe, and economical energy source cannot be exploited unless the energy is accumulated or converted into more useful forms. The conversion of solar energy into hydrogen via the water-splitting process, assisted by photo-semiconductor catalysts, is one of the most promising technologies for the future because large quantities of hydrogen can potentially be generated in a clean and sustainable manner. This Minireview provides an overview of the principles, approaches, and research progress on solar hydrogen production via the water-splitting reaction on photo-semiconductor catalysts. It presents a survey of the advances made over the last decades in the development of catalysts for photochemical water splitting under visible-light irradiation. The Minireview also analyzes the energy requirements and main factors that determine the activity of photocatalysts in the conversion of water into hydrogen and oxygen using sunlight. Remarkable progress has been made since the pioneering work by Fujishima and Honda in 1972, but he development of photocatalysts with improved efficiencies for hydrogen production from water using solar energy still faces major challenges. Research strategies and approaches adopted in the search for active and efficient photocatalysts, for example through new materials and synthesis methods, are presented and analyzed.
"Photocatalytic hydrogen evolution over different g-C 3 N 4 samples -either alone or loaded with 1.0 wt.% of Pt-was evaluated under visible light irradiation (>465 nm) using triethanolamine (TEA) as a scavenger, at room temperature and atmospheric pressure following a procedure similar to a previously reported method . Prior to catalyst testing, blank experiments showed that no reaction occurs when the system was illuminated in the absence of catalyst or in the presence of catalyst without illumination. "
[Show abstract][Hide abstract] ABSTRACT: Se-modified g-C3N4 was synthesized from sonicated aqueous suspensions of melamine cyanurate and SeO2. The different thermal condensation temperatures in the 500-650 ºC range were found to influence the photophysical properties and hydrogen evolution rates. H2 evolution increased dramatically by two orders of magnitude when Pt co-catalyst (1 wt.%) was incorporated, reaching an HER of 75 µmol H2/h.
International Journal of Hydrogen Energy 04/2015; 40:7273-7281. DOI:10.1016/j.ijhydene.2015.04.063 · 3.31 Impact Factor
"In recent years, several catalytic and photocatalytic applications have been broadly studied in Nb-based materials due to their redox, strong acidic and photosensitivity properties  . For example, oxide materials based on the niobate have showed activity and high selectivity in different catalytic processes such as oxidative dehydrogenation of alkanes , oxidative coupling of methane , dry methane reforming (DMR) , ethylene homologation reaction (EHR)  and photocatalysis  . Although TiO 2 oxide is widely used as photocatalytic material, currently niobate-based materials such as KNb 3 O 8 , K 6 Nb 10.8 O 30 , K 4 Ce 2 Nb 10 O 30 , NiNb 2 O 6 , K 4 Nb 6 O 17 , and NiO–KTiNbO 5 have been widely studied because of their excellent photocatalytic properties  . "
[Show abstract][Hide abstract] ABSTRACT: The photocatalytic activity of a new nanostructured Ni-doped niobate KSr2(Ni0.75Nb4.25)O15-delta was studied using the phenol red dye as a test molecule and the influence of amorphous carbon deposits upon the photoactivity of the niobate-based materials was also verified. KSr2(Ni0.75Nb4.25)O15-delta powder was prepared by a high energy ball milling method and the C-KSr2(Ni0.75Nb4.25)O15-delta composite by the partial pyrolysis of the niobate dispersed in a polyester matrix. Materials were characterized by FM spectroscopy and X-ray diffraction (XRD). The diffraction line profile and the refinement of the structural parameters of KSr2(Ni0.75Nb4.25)O15-delta were derived by the Rietveld method. Both samples showed similar phenol red photodegradation under steady-state kinetic conditions. However, amorphous carbon seems to beneficially affect the reaction mechanism which followed first order kinetics. In terms of KSr2(Ni0.75Nb4.25)O15-delta concentration a clear enhancement in the photoactivity of the niobate in the presence of amorphous carbon by a factor 4.7 was found suggesting a synergy effect between both solids. We conclude that C-KSr2(Ni0.75Nb4.25)O15-delta composite can be employed for the photocatalytic degradation of diluted pollutants.
Ceramics International 08/2014; 40(7):9525-9534. DOI:10.1016/j.ceramint.2014.02.026 · 2.61 Impact Factor
"Fig. 2 shows the XRD patterns of samples SAM-4 and SAM-8. Both diffractograms are characterized by having reflections at intermediate positions to the corresponding ZnS and CdS precursors, indicating that these compounds have been synthesized as mixed oxide solid solutions (Navarro et al. 2009). On impregnation of SAM-4 and SAM-8 over TiO 2 NWs (samples SAM-4A and SAM-8A) no characteristics peaks of the original ZnCdFeS or ZnCdFeCuS nanoparticles were observed and only the characteristics reflections of the rutile phase corresponding to the supporting material (TiO 2 NWs) were identified (see Fig. 2). "
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