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Single-particle-type suspension reactors and other membrane-free reactor designs for photoelectrochemical (PEC) water splitting, although promising for low-cost H2 production, suffer the drawback of H2 and O2 co-evolution leading to product losses through back reactions. These back reactions need to be minimized to increase the solar-to-hydrogen (STH) efficiency. H2/O2 co-evolution also raises safety considerations, and a large-scale facility should maintain the H2 concentration below the lower flammability limit with O2 to eliminate explosion hazards. Herein, inert gas bubbling through the electrolyte was investigated with a tandem semiconductor for light-driven PEC water splitting without applied electrical bias as a technique to mitigate back reactions and maintain the output H2 safely below the lower flammability limit during co-evolution. A planar structure of nanoparticulate-Pt/Ni/np+-Si/FTO/TiO2 was fabricated into both wired-electrode and fully integrated configurations capable of unassisted solar water splitting, though additional UV bias increased the current density and gas production rates. The device was characterized in aqueous electrolyte from alkaline to neutral conditions to balance water-splitting activity and durability against corrosion, displaying strong stability in a pH 11 buffer solution. Moreover, the H2 faradaic efficiency was increased from 59% without bubbling to > 98% using inert carrier gas to increase the mass transfer of products to the gas phase. Integrated tandem photoelectrode performance indicated a tradeoff in bubbling flow rate between decreased back reactions and decreased light absorption due to bubble reflectance.
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This content will become publicly available on March 14, 2026
Structured bubbling flow in fluidized beds with oscillating gas injection which alternates with horizontal position
Abstract Structured bubbling with a triangular lattice pattern has been demonstrated previously to form in fluidized beds with oscillated gas injection velocity. Here, we demonstrate using two‐fluid model simulations that dividing the gas distributor into slices and oscillating gas flow with a phase offset between consecutive slices enables structured bubbling to form with a wider range of bubble sizes and lattice configurations. Local particle solidification below bubbles leads to the formation of these structures, as manifested in high particle pressures in simulations. Varying the number of slices and phase offset enables a number of configurations that mix particles faster than cases with conventional structured bubbling or unstructured bubbling with the same overall gas flow rate.
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- Award ID(s):
- 2144763
- PAR ID:
- 10641610
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- AIChE Journal
- Volume:
- 71
- Issue:
- 7
- ISSN:
- 0001-1541
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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