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Optimizing photochemical charge separation at nanoscale interfaces as a way to improve the solar energy to fuel conversion efficiency of water splitting photocatalysts

Grant number: 14/22388-3
Support type:Scholarships abroad - Research Internship - Post-doctor
Effective date (Start): February 01, 2015
Effective date (End): January 31, 2016
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
Principal researcher:Ana Flávia Nogueira
Grantee:Mauricio Alves de Melo Junior
Supervisor abroad: Frank E. Osterloh
Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
Research place: University of California, Davis (UC Davis), United States  


The development of porous titanium and niobium-based semiconductors, obtained from the pillaring of lamellar K2Ti4O9 and K4Nb6O17 solids, and their decoration with different co-catalysts nanoparticles, to be applied as photocatalysts for the production of H2 from water splitting is proposed in this research project. The expansible features of the lamellar structures of K2Ti4O9 and K4Nb6O17 will be explored for the introduction of titanium dioxide (TiO2) pillars into their interlamellar spaces through the pillaring process, creating new photoactive sites as well as increasing the surface area and stabilities of the materials. Unfortunately, such configuration makes these pillared semiconductors only able to absorb ultraviolet radiation, which corresponds to less than 6 % of the solar spectrum, because of the relative high band gap values of niobate, titanate and TiO2 semiconductors, which are higher than 3.0 eV. Thus, in the aim of overcoming this restriction, the pillared solids will be decorated with the co-catalysts Au, Ag, and NiO nanoparticles, to promote a wider absorption of the solar spectrum and/or favor the suppression of the fast electron-hole recombination. The synthesized materials will be characterized by largely applied techniques such as X-ray diffraction, scanning and transmission electron microscopy, thermogravimetry, diffuse reflectance spectroscopy, elemental analysis, infrared spectroscopy, and transient absorption spectroscopy. More specifically, the photochemical charge separation on the nanoscale, responsible for the water splitting phenomenon, will be analyzed through surface photovoltage spectroscopy (SPS), which probes contact potential difference changes on the materials upon excitation with sunlight. This technique will be useful to elucidate the mechanism of photovoltage origin in each case, and the results will be correlated with the amount of hydrogen generated through water splitting under solar light. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
MELO, JR., MAURICIO A.; CARMINATI, SAULO A.; BETTINI, JEFFERSON; NOGUEIRA, ANA F.. Pillaring and NiOx co-catalyst loading as alternatives for the photoactivity enhancement of K2Ti4O9 towards water splitting. SUSTAINABLE ENERGY & FUELS, v. 2, n. 5, p. 958-967, . (13/05654-9, 14/22388-3)
MELO, JR., MAURICIO A.; WU, ZONGKAI; NAIL, BENJAMIN A.; DE DENKO, ALEXANDRA T.; NOGUEIRA, ANA F.; OSTERLOH, FRANK E.. Surface Photovoltage Measurements on a Particle Tandem Photocatalyst for Overall Water Splitting. Nano Letters, v. 18, n. 2, p. 805-810, . (14/22388-3)

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