BiVO4-Based Heterostructured Photocatalysts for Solar Water Splitting: A Review
Hydrogen is a clean and storable energy carrier of the future when it is produced from a renewable energy source via a CO2-neutal process. Solar water splitting is such a renewable and sustainable energy production method utilizing sun light and water, the most abundant resources on earth. Among conceived solar hydrogen production methods, the photoelectrochemical (PEC) cell is most promising, in which the semiconductor photoelectrodes have to satisfy a number of requirements; a proper band gap energy for strong visible light absorption, band edge positions enabling oxidation or reduction of water, chemical and electrochemical stability in water under illumination, fast transport of the photo-generated electrons and holes in the semiconductor, low over-potentials for the electrode reactions, and low cost. Monoclinic BiVO4 satisfies many of these material requirements; a moderate band gap (∼2.4 eV) that allows 9.2% of theoretical solar-to-hydrogen (STH) efficiency, fine hole conductivity, good stability in neutral electrolytes, low price, and environmentally benign characteristics. But it also has critical drawbacks of poor electron transfer and sluggish water oxidation kinetics. Formation of heterostructures is a simple but effective strategy to improve the performance of BiVO4-based photocatalysts in light harvesting, long term stability and solar-to-chemical energy conversion efficiency in solar water splitting. This article reviews three types of heterostructures to modify BiVO4 including formation of heterojunctions with another semiconductor, addition of a charge transfer mediator, and loading a co-catalyst, which lead to great performance improvement in PEC water splitting. In all cases, improved performance comes from suppressed electron–hole recombination by facilitated charge separation in various interfaces along the charge transfer pathways. Only a limited number of selected examples are discussed that could provide good illustration of the underlying concepts and recent developments.
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Document Type: Review Article
Publication date: December 1, 2014
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- ENERGY AND ENVIRONMENT FOCUS is a multidisciplinary peer-reviewed international research journal consolidating research activities in all experimental and theoretical aspects of energy and environment with an interdisciplinary approach. The research topics include the preparation and characterization of advanced functional materials and their utilization in various energy and environmental applications, to name a few; fuel cells, batteries, solar cells, light emitting diodes, solar cells, optoelectronic devices, thermoelectric, clean energy, bio-fuels and bio-refineries, supercapacitors, hydrogen energy (storage and generation), geothermal energy, nanogenerators, self-powered devices and systems, catalysis, biomass and bioenergy, static and dynamic energy conversion; energy efficiency and management, nuclear energy, fossil fuels, geothermal, wind energy, electrolysis, and photothermal devices, environmental science and technology (environmental chemistry, physics biology and engineering) including climate change, greenhouse gases and global warming, ecology, environmental toxicology, industrial wastewater and sewage treatment, geosciences, atmospheric, terrestrial and aquatic environments, pollution and environmental control, hazardous substances, radioactive contamination, noise pollution, effects of air, water, and soil contaminations on human health, environmental public health policies, soil environmental management and technologies, environmental policies, rules and regulations, conservation of natural resources, and all aspects of theoretical modeling related with energy and environment.
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