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   https://doi.org/10.1021/jz2001375  

   Yahyaie, Iman ; McEleney, Kevin ; Walter, Michael ; Oliver, Derek R. ; Thomson, Douglas J. ; Freund, Michael S. ; Lewis, Nathan S. ( March 2011 , The Journal of Physical Chemistry Letters)
2. Effects of bubbles on the electrochemical behavior of hydrogen-evolving Si microwire arrays oriented against gravity

   https://doi.org/10.1039/D0EE00356E  

   Kempler, Paul A. ; Coridan, Robert H. ; Lewis, Nathan S. ( January 2020 , Energy & Environmental Science)

   The size-distribution, coverage, electrochemical impedance, and mass-transport properties of H 2 gas-bubble films were measured for both planar and microwire-array platinized n + -Si cathodes performing the hydrogen-evolution reaction in 0.50 M H 2 SO 4 (aq). Inverted, planar n + -Si/Ti/Pt cathodes produced large, stationary bubbles which contributed to substantial increases in ohmic potential drops. In contrast, regardless of orientation, microwire array n + -Si/Ti/Pt cathodes exhibited a smaller layer of bubbles on the surface, and the formation of bubbles did not substantially increase the steady-state overpotential for H 2 (g) production. Experiments using an electroactive tracer species indicated that even when oriented against gravity, bubbles enhanced mass transport at the electrode surface. Microconvection due to growing and coalescing bubbles dominated effects due to macroconvection of gliding bubbles on Si microwire array cathodes. Electrodes that maintained a large number of small bubbles on the surface simultaneously exhibited low concentrations of dissolved hydrogen and small ohmic potential drops, thus exhibiting the lowest steady-state overpotentials. The results indicate that microstructured electrodes can operate acceptably for unassisted solar-driven water splitting in the absence of external convection and can function regardless of the orientation of the electrode with respect to the gravitational force vector. 

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3. Photoelectrochemical Behavior of Planar and Microwire-Array Si|GaP Electrodes

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4. Optical Properties and Photocatalytic Performance of Si/TiO 2 Tandem Semiconductor Microwire Slurries

   https://doi.org/10.1021/acs.energyfuels.3c00568  

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   Semiconductor particle suspension reactors hold promise as a possible low-cost strategy for solar water-splitting, but they face several challenges that have inhibited their solar-to hydrogen (STH) efficiencies. A tandem microparticle with a buried junction addresses some of these challenges and offers a pathway to high STH efficiency. As a slurry, the tandem microparticles need to be suspended and well dispersed with maximum light absorption for a minimal photoactive particle concentration. Herein, proof-of-concept Ni/np+-Si/FTO/TiO2 tandem microwire structures capable of unassisted solar water-splitting were investigated as a slurry using uplifting N2 carrier gas bubbles. Transmittance, reflectance, and absorptance of the slurry were characterized as a function of wavelength, bubble flowrate, and tandem microwire concentration using an integrating sphere. Notably, a slurry absorptance of 70−85% was achieved with only 1% of the solution volume filled with a photoactive material. Photochemical activity of the slurry was characterized with in situ monitoring of the photodegradation of methylene blue, including the effects of particle concentration, bubble flowrate, spectral mismatch, intermixed light scattering particles, and a back reflector. 

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   https://doi.org/10.1039/c2ee23115h  

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