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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

Theoretical required surface area for electrodes.Combinations of NiFe – NiMo in alkaline solution for 3PVs, red line; NiFe – Ni in alkaline for 4PVs, blue line; and NiCo – NiMo in near neutral pH solution for 4PVs, blue dashed line were illustrated as a function of target current at 1.5 V for 3PVs and 1.8 V for 4PVs calculated from current-voltage properties for SPHELARs (Fig. 4) and electrocatalysts (Supplementary Fig. S2). The required surface area for 3PVs, 3PVs with MCPET, 4PVs, and 4PVs with MCPET are illustrated by ○, ●, □, and ■, respectively.
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f5: Theoretical required surface area for electrodes.Combinations of NiFe – NiMo in alkaline solution for 3PVs, red line; NiFe – Ni in alkaline for 4PVs, blue line; and NiCo – NiMo in near neutral pH solution for 4PVs, blue dashed line were illustrated as a function of target current at 1.5 V for 3PVs and 1.8 V for 4PVs calculated from current-voltage properties for SPHELARs (Fig. 4) and electrocatalysts (Supplementary Fig. S2). The required surface area for 3PVs, 3PVs with MCPET, 4PVs, and 4PVs with MCPET are illustrated by ○, ●, □, and ■, respectively.

Mentions: where ISC is the short-circuit current (achievable maximum photocurrent by the PVs) and jcat represents the electrocatalytic current density at the operating voltage (at which the ISC is obtained). ISC was adopted from the I-V curves for the SPHELARs (Fig. 4), and jcat was obtained from the j-E curves for the electrocatalysts (Supplementary Fig. S2). In Fig. 5, the calculated minimum electrode surface area is compiled against the electric current, where the inverse of the slope (mA cm−2) corresponds to the current density over the electrode at the operating voltage. The y-value at the target current, ISC, corresponds to the SAmin needed to obtain ISC. It should be noted that the surface areas of both the anode and the cathode were the same. The calculated SAmin for each electrode configuration is summarized in Supplementary Table S2. The power-voltage relationship for the PV and water electrolysis with the optimum electrode surface area is compared in Supplementary Fig. S4.


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)

Theoretical required surface area for electrodes.Combinations of NiFe – NiMo in alkaline solution for 3PVs, red line; NiFe – Ni in alkaline for 4PVs, blue line; and NiCo – NiMo in near neutral pH solution for 4PVs, blue dashed line were illustrated as a function of target current at 1.5 V for 3PVs and 1.8 V for 4PVs calculated from current-voltage properties for SPHELARs (Fig. 4) and electrocatalysts (Supplementary Fig. S2). The required surface area for 3PVs, 3PVs with MCPET, 4PVs, and 4PVs with MCPET are illustrated by ○, ●, □, and ■, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Theoretical required surface area for electrodes.Combinations of NiFe – NiMo in alkaline solution for 3PVs, red line; NiFe – Ni in alkaline for 4PVs, blue line; and NiCo – NiMo in near neutral pH solution for 4PVs, blue dashed line were illustrated as a function of target current at 1.5 V for 3PVs and 1.8 V for 4PVs calculated from current-voltage properties for SPHELARs (Fig. 4) and electrocatalysts (Supplementary Fig. S2). The required surface area for 3PVs, 3PVs with MCPET, 4PVs, and 4PVs with MCPET are illustrated by ○, ●, □, and ■, respectively.
Mentions: where ISC is the short-circuit current (achievable maximum photocurrent by the PVs) and jcat represents the electrocatalytic current density at the operating voltage (at which the ISC is obtained). ISC was adopted from the I-V curves for the SPHELARs (Fig. 4), and jcat was obtained from the j-E curves for the electrocatalysts (Supplementary Fig. S2). In Fig. 5, the calculated minimum electrode surface area is compiled against the electric current, where the inverse of the slope (mA cm−2) corresponds to the current density over the electrode at the operating voltage. The y-value at the target current, ISC, corresponds to the SAmin needed to obtain ISC. It should be noted that the surface areas of both the anode and the cathode were the same. The calculated SAmin for each electrode configuration is summarized in Supplementary Table S2. The power-voltage relationship for the PV and water electrolysis with the optimum electrode surface area is compared in Supplementary Fig. S4.

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