PHOTOPHYSICAL AND PHOTOCHEMICAL SYSTEMS WITH SEMICONDUCTORS FOR THE CONVERSION OF SOLAR ENERGY. A REVIEW

Electrochemical energy sources are an alternative to replace technology based on the burning of fossil fuels. In an elec-trochemical system the potential drop spreads over a very narrow region at an interphase, creating high electric fields.So, there are good technological reasons to study semiconductor / electrolyte interphases. Currently, one of the ways touse renewable resources is through photovoltaic technology that directly converts solar radiation into electrical energy.This technology is manufactured from semiconductors, generally silicon, following an extremely careful and expensivemanufacturing procedure. An option for photovoltaic devices is photoelectrochemical cells.These cells are made bythe contact of a semiconductor electrode with a solution, which can be easily prepared and offers the possibility oflow-cost manufacturing. Understanding how these devices work requires knowledge of the characteristics of semicon-ductors and how these materials behave in contact with an electrolytic solution and under illumination by sunlight. Thepresent work describes, through an updated review, the principles and applications of semiconductor electrodes as themain components in a photoelectrochemical solar cell (PEC), to carry out chemical reactions of technological interest.In addition, the elements that are required for the improvement in the performance and construction of the PEC are discussed.

Charge Injection and Dielectric Characteristics of Polyethylene Terephthalate Based on Semiconductor Electrodes

Employing a novel semiconductor electrode in comparison with the traditional semiconductor electrode made of polyethylene/ethylene-vinyl-acetate copolymer/carbon-black (PE/EVA/CB) composite, characteristic charge carriers are injected into polyethylene terephthalate (PET) as a polymer dielectric paradigm, which will be captured by specific deep traps of electrons and holes. Combined with thermal stimulation current (TSC) experiments and first-principles electronic-state calculations, the injected charges from the novel electrode are characterized, and the corresponding dielectric behavior is elucidated through DC conductance, electrical breakdown and dielectric spectrum tests. TSC experiments with novel and traditional semiconductor electrodes can distinguish the trapping characteristics between hole and electron traps in polymer dielectrics. The observable discrepancy in space charge-limited conductance and the stable dielectric breakdown strength demonstrate that the electron injection into PET film specimen is restricted by using the novel semiconductor electrode. Attributed to the favorable suppression on the inevitable electron injections from metal electrodes, adopting novel i-electrode can avoid the evident abatement of dipole orientation polarization caused by space charge clamp, but will engender the accessional high-frequency dielectric loss from dielectric relaxations of interface charges at i-electrodes.

Improvement of Photoelectrochemical HClO Production under Visible Light Irradiation by Loading Cobalt Oxide onto BiVO4 Photoanode

Photoelectrochemical simultaneous production of H2 and hypochlorous acid (HClO) as a value-added oxidation reagent compared with O2 on a semiconductor electrode by using visible light is one of the breakthrough...

Enhancement of Biosensors by Implementing Photoelectrochemical Processes

Research on biosensors is growing in relevance, taking benefit from groundbreaking knowledge that allows for new biosensing strategies. Electrochemical biosensors can benefit from research on semiconducting materials for energy applications. This research seeks the optimization of the semiconductor-electrode interfaces including light-harvesting materials, among other improvements. Once that knowledge is acquired, it can be implemented with biological recognition elements, which are able to transfer a chemical signal to the photoelectrochemical system, yielding photo-biosensors. This has been a matter of research as it allows both a superior suppression of background electrochemical signals and the switching ON and OFF upon illumination. Effective electrode-semiconductor interfaces and their coupling with biorecognition units are reviewed in this work.