Photoelectrocatalytic Systems

Thin-lilm photoelectrodes are needed in photoelectrocatalytic systems to apply a bias potential, either for the photoelectrode characterization or to facilitate the photocatalytic reactions. However, to be able to present a more comprehensive view on the performance of different materials, our subsequent discussions will focus on particulate semiconductor photocatalysts since the latter have been much more extensively investigated. Their electronic band structure (i.e., both the bandgap energy and the positions of CB and VB) is the key factor to determine whether or not a semiconductor material is suitable for a specific photocatalytic reaction, as will be demonstrated by reviewing a number of selected metal oxides and cou-pled/composite materials based on various semiconductors. 

P. Bogdanoff, N. Alonso-Vante, on-line determination via differential electrochemical mass spectroscopy (DEMS) of chemical products formed in photoelectrocatalytical systems. Berichte der Bunsengellschaft fur physikalische Chem. 97, 940-943 (1993)... 

As interfacial properties control charge transfer, surface recombination, and stabihty, their optimization is a key to effldent and stable operation in solar energy-converting structures and devices. The examples considered here are related to the development of either photovoltaic or photoelectrocatalytic efficient systems that wiU be described in Sections 2.5 and 2.6. The case studies begin with the more detailed continuation of the above described formation of nanotopographies on Si... 

A newly-designed photoelectrocatalytic (PEC) reactor for CO2 reduction, which combines photocatalysis by Ti02 and electrocatalysis by carbon nanotubes (CNT), has recently been proposed (Fig. 7) [152]. A proton-conductive Nafion membrane connects the Ti02 and CNT. Irradiation of the combined system of nano-structured Ti02 deposited on a metal Ti electrode with Pt modified CNT deposited on carbon sheet caused water splitting to H2 and O2. A half-cell for the cathodic electrode, i.e., Pt or Fe modified CNT electrode, produces various organic molecules such as 2-propanol due to electrocatalytic reduction of CO2 on the electrode. The proposed PEC reactor is incomplete in its present state. However, these systems are expected to couple water splitting and CO2 reduction, and thus it may establish a new artificial photosynthetic system. 

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