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A miniature solar device for overall water splitting consisting of series-connected spherical silicon solar cells.

Kageshima Y, Shinagawa T, Kuwata T, Nakata J, Minegishi T, Takanabe K, Domen K - Sci Rep (2016)

Bottom Line: Impacts of the configuration on the PV module performance were carefully analyzed, revealing that a drastic increase in the photocurrent (≈20%) was attained by the effective utilization of a reflective sheet.Separate investigations on the electrocatalyst performance showed that non-noble metal based materials with reasonably small sizes (<0.80 cm(2)) exhibited substantial currents at the PV working voltage.By combining the observations of the PV characteristics, light management and electrocatalyst performance, solar-driven overall water splitting was readily achieved, reaching solar-to-hydrogen efficiencies of 7.4% (3PVs) and 6.4% (4PVs).

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.

ABSTRACT
A novel "photovoltaics (PV) + electrolyzer" concept is presented using a simple, small, and completely stand-alone non-biased device for solar-driven overall water splitting. Three or four spherical-shaped p-n junction silicon balls were successfully connected in series, named "SPHELAR." SPHELAR possessed small projected areas of 0.20 (3PVs) and 0.26 cm(2) (4PVs) and exhibited working voltages sufficient for water electrolysis. Impacts of the configuration on the PV module performance were carefully analyzed, revealing that a drastic increase in the photocurrent (≈20%) was attained by the effective utilization of a reflective sheet. Separate investigations on the electrocatalyst performance showed that non-noble metal based materials with reasonably small sizes (<0.80 cm(2)) exhibited substantial currents at the PV working voltage. By combining the observations of the PV characteristics, light management and electrocatalyst performance, solar-driven overall water splitting was readily achieved, reaching solar-to-hydrogen efficiencies of 7.4% (3PVs) and 6.4% (4PVs).

No MeSH data available.


Related in: MedlinePlus

Diffuse reflectance spectra for reflectors.Red line indicates microfoamed reflective sheet (MCPET, Frukawa electric co. ltd.) and black line means stainless mirror with wavelength of 300–1200 nm.
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f2: Diffuse reflectance spectra for reflectors.Red line indicates microfoamed reflective sheet (MCPET, Frukawa electric co. ltd.) and black line means stainless mirror with wavelength of 300–1200 nm.

Mentions: Because the spherical-shaped SPHELAR PV module receives irradiated light from all directions, the PV conjugated with some reflector that collects scattered and/or reflected photons are expected to improve the photoconversion efficiency4748. Compared with conventional thin film approaches, such module is much simpler. Additionally, this spherical shape of the SPHELAR PV module is definitely a great advantage over the conventional flat plate structure, because it can maximize the light irradiation for longer time in the daytime in spite of the daily sunlight angle change. In this study, a micro-foamed reflective sheet (MCPET; Furukawa Electric Co. Ltd.) was utilized as a reflector for the SPHELAR module. Figure 2 compiles the measured diffuse reflectance of MCPET and a mirror. The reflectance of MCPET was higher than the mirror above approximately 430 nm, implying that MCPET was capable of reflecting and scattering a larger number of photons in most of the visible and near infrared range than a common mirror. This observation suggests that use of MCPET as a reflector would greatly enhance the photocurrent.


A miniature solar device for overall water splitting consisting of series-connected spherical silicon solar cells.

Kageshima Y, Shinagawa T, Kuwata T, Nakata J, Minegishi T, Takanabe K, Domen K - Sci Rep (2016)

Diffuse reflectance spectra for reflectors.Red line indicates microfoamed reflective sheet (MCPET, Frukawa electric co. ltd.) and black line means stainless mirror with wavelength of 300–1200 nm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4834539&req=5

f2: Diffuse reflectance spectra for reflectors.Red line indicates microfoamed reflective sheet (MCPET, Frukawa electric co. ltd.) and black line means stainless mirror with wavelength of 300–1200 nm.
Mentions: Because the spherical-shaped SPHELAR PV module receives irradiated light from all directions, the PV conjugated with some reflector that collects scattered and/or reflected photons are expected to improve the photoconversion efficiency4748. Compared with conventional thin film approaches, such module is much simpler. Additionally, this spherical shape of the SPHELAR PV module is definitely a great advantage over the conventional flat plate structure, because it can maximize the light irradiation for longer time in the daytime in spite of the daily sunlight angle change. In this study, a micro-foamed reflective sheet (MCPET; Furukawa Electric Co. Ltd.) was utilized as a reflector for the SPHELAR module. Figure 2 compiles the measured diffuse reflectance of MCPET and a mirror. The reflectance of MCPET was higher than the mirror above approximately 430 nm, implying that MCPET was capable of reflecting and scattering a larger number of photons in most of the visible and near infrared range than a common mirror. This observation suggests that use of MCPET as a reflector would greatly enhance the photocurrent.

Bottom Line: Impacts of the configuration on the PV module performance were carefully analyzed, revealing that a drastic increase in the photocurrent (≈20%) was attained by the effective utilization of a reflective sheet.Separate investigations on the electrocatalyst performance showed that non-noble metal based materials with reasonably small sizes (<0.80 cm(2)) exhibited substantial currents at the PV working voltage.By combining the observations of the PV characteristics, light management and electrocatalyst performance, solar-driven overall water splitting was readily achieved, reaching solar-to-hydrogen efficiencies of 7.4% (3PVs) and 6.4% (4PVs).

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.

ABSTRACT
A novel "photovoltaics (PV) + electrolyzer" concept is presented using a simple, small, and completely stand-alone non-biased device for solar-driven overall water splitting. Three or four spherical-shaped p-n junction silicon balls were successfully connected in series, named "SPHELAR." SPHELAR possessed small projected areas of 0.20 (3PVs) and 0.26 cm(2) (4PVs) and exhibited working voltages sufficient for water electrolysis. Impacts of the configuration on the PV module performance were carefully analyzed, revealing that a drastic increase in the photocurrent (≈20%) was attained by the effective utilization of a reflective sheet. Separate investigations on the electrocatalyst performance showed that non-noble metal based materials with reasonably small sizes (<0.80 cm(2)) exhibited substantial currents at the PV working voltage. By combining the observations of the PV characteristics, light management and electrocatalyst performance, solar-driven overall water splitting was readily achieved, reaching solar-to-hydrogen efficiencies of 7.4% (3PVs) and 6.4% (4PVs).

No MeSH data available.


Related in: MedlinePlus