New-Generation Oxide Semiconductors for Solar Energy Conversion and Environmental Remediation

2012 ◽  
Vol 17 ◽  
pp. 185-191 ◽  
Author(s):  
Krishnan Rajeshwar ◽  
Norma R. de Tacconi ◽  
Hari K. Timmaji

Two Oxide Semiconductors, Namely, Bismuth Vanadate (BiVO4) and Silver Bismuth Tungstate (AgBiW2O8) Were Prepared by Solution Combustion Synthesis and their Attributes as Photocatalysts Were Comparatively Evaluated. A Key Conclusion of this Study Is that the Optical Characteristics Alone Provide only a Partial Glimpse into the Applicability of a Given Semiconductor for Solar Energy Conversion and Environmental Remediation. Thus while the Optical Bandgap of Bivo4 Is Lower than Agbiw2o8 (and Thus Is Able to Harness a Greater Portion of the Solar Spectrum), its Photocatalytic Activity for the Degradation of a Dye Is Inferior. this Finding Underlines the Fact that other Characteristics of the Semiconductor (band-Edge Alignment, Surface Quality Etc) Also Play as Critical a Role as the Optical Properties.

Nanomaterials ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 1201 ◽  
Author(s):  
James Walshe ◽  
Pauraic Mc Carron ◽  
Conor McLoughlin ◽  
Sarah McCormack ◽  
John Doran ◽  
...  

Exploiting solar energy using photo-thermal (PT) and/or hybridised photovoltaic/thermal (PVT) systems can represent a viable alternative to the growing demand for renewable energy. For large-scale implementation, such systems require thermal fluids able to enhance the combined conversion efficiency achievable by controlling the ‘thermal’ and ‘electrical’ components of the solar spectrum. Nanofluids are typically employed for these purposes and they should exhibit high heat-transfer capabilities and optical properties tuned towards the peak performance spectral window of the photovoltaic (PV) component. In this work, novel nanofluids, composed of highly luminescent organic molecules and Ag nanoparticles dispersed within a base fluid, were tested for PT and PVT applications. These nanofluids were designed to mimic the behaviour of luminescent down-shifting molecules while offering enhanced thermo-physical characteristics over the host base fluid. The nanofluids’ conversion efficiency was evaluated under a standard AM1.5G weighted solar spectrum. The results revealed that the Ag nanoparticles’ inclusion in the composite fluid has the potential to improve the total solar energy conversion. The nanoparticles’ presence minimizes the losses in the electrical power component of the PVT systems as the thermal conversion increases. The enhanced performances recorded suggest that these nanofluids could represent suitable candidates for solar energy conversion applications.


2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Kristine A. Zhang ◽  
David Ma ◽  
Ying-Chih Pu ◽  
Yat Li

Solar power holds great potential as an alternative energy source, but current photovoltaic cells have much room for improvement in cost and efficiency. Our objective was to develop metal nanostructures whose surface plasmon resonance (SPR) spectra closely match the solar spectrum to enhance light absorption and scattering. We employed the finite-difference time-domain simulation method to evaluate the effect of varying key parameters. A novel nanostructure with SPR absorption matching a region of the solar spectrum (300 to 1500 nm) that contains 90% of solar energy was successfully designed. This structure consists of a large gold-silica core-shell structure with smaller gold nanoparticles and nanorods on its surface. Such complex nanostructures are promising for broad and tunable absorption spectra. In addition, we investigated the SPR of silver nanoparticle arrays, which can achieve scattering close to the solar spectrum. We demonstrated an improvement in efficiency of over 30% with optimal nanoparticle radius and periods of 75 nm and 325 nm, respectively. In combination, our studies enable high-efficiency, tunable, and cost-effective enhancement of both light absorption and scattering, which has potential applications in solar energy conversion as well as biomedical imaging.


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