Modeling, Simulation, and Implementation of Solar‐Driven Water‐Splitting Devices

Xiang, Chengxiang; Weber, Adam Z.; Ardo, Shane; Berger, Alan; Chen, Yi Kai; Coridan, Robert H.; Fountaine, Katherine T.; Haussener, Sophia; Hu, Shu; Li, Rui; Lewis, Nathan S.; Modestino, Miguel A.; Shaner, Matthew R.; Singh, Meenesh R.; Stevens, John C.; Sun, Ke; Walczak, Karl

doi:10.1002/anie.201510463

Cited by 132 publications

(111 citation statements)

References 142 publications

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“…The EQE for each sub-cell is then given by equation (2). Workfunction measurements by UPS for the tandem, for TiO 2 on the tandem and for Rh metal.…”

Section: Supplementary Textmentioning

confidence: 99%

Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency

et al. 2018

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Recent rapid progress in efficiencies for solar water splitting by photoelectrochemical devices has enhanced its prospects to enable storable renewable energy. Efficient solar fuel generators all use tandem photoelectrode structures, and advanced integrated devices incorporate corrosion protection layers as well as heterogeneous catalysts. Realization of near thermodynamic limiting performance requires tailoring the energy band structure of the photoelectrode and also the optical and electronic properties of the surface layers exposed to the electrolyte. Here, we report a monolithic device architecture that exhibits reduced surface reflectivity in conjunction with metallic Rh nanoparticle catalyst layers that minimize parasitic light absorption. Additionally, the anatase TiO 2 protection layer on the photocathode creates a favorable internal band alignment for hydrogen evolution. An initial solar-to-hydrogen efficiency of 19.3 % is obtained in acidic electrolyte and an efficiency of 18.5 % is achieved at neutral pH condition (under simulated sunlight). Main TextAdvances in the field of artificial photosynthesis 1 have led to the development of functional prototypes for photoelectrochemical water splitting 2 , featuring improved photoelectrode stability through the use of corrosion protection layers 3 and the realization of systems for unassisted water splitting 4-6 in integrated monolithic devices. The requirement for the device operating voltage under illumination to exceed the thermodynamic potential difference for water dissociation of 1.23 V imposes constraints on the energy bandgaps for the photoelectrode absorber layers and their combined operating potential in a series-connected tandem configuration. Several strategies have been followed. Early prototypes used single absorber

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“…The EQE for each sub-cell is then given by equation (2). Workfunction measurements by UPS for the tandem, for TiO 2 on the tandem and for Rh metal.…”

Section: Supplementary Textmentioning

confidence: 99%

Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency

et al. 2018

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“…For photo-induced watersplitting reactions, multi-ionic solutions are commonly used to control electrostatic potentials and engineer the pH of electrolytes. [20,21,64] There, large-scale pH gradients were observed. The observed large-scale pH gradients could be related to the length-scale separation between charge density profiles and concentration profiles, which could be possible for multi-ionic solutions.…”

Section: Resultsmentioning

confidence: 99%

Possible influence of the Kuramoto length in a photo-catalytic water splitting reaction revealed by Poisson–Nernst–Planck equations involving ionization in a weak electrolyte

Suzuki

Seki

2018

Chemical Physics

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We studied ion concentration profiles and the charge density gradient caused by electrode reactions in weak electrolytes by using the Poisson-Nernst-Planck equations without assuming charge neutrality. In weak electrolytes, only a small fraction of molecules is ionized in bulk. Ion concentration profiles depend on not only ion transport but also the ionization of molecules. We considered the ionization of molecules and ion association in weak electrolytes and obtained analytical expressions for ion densities, electrostatic potential profiles, and ion currents. We found the case that the total ion density gradient was given by the Kuramoto length which characterized the distance over which an ion diffuses before association. The charge density gradient is characterized by the Debye length for 1:1 weak electrolytes. We discuss the role of these length scales for efficient water splitting reactions using photo-electrocatalytic electrodes.

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“…[5,6] Furthermore, because both light absorption and reactionoccur on the same monolithic materials, this approach is expectedt ob es imple and cost-effective. [7,8] High STH values (above 10 %) have been demonstrated experimentally in systems employing ap hotovoltaic bias and electrocatalysts. [9] In contrast, PEC cells consisting of ap hotocathode-photoanode combination have shown insufficient STH results.…”

Section: Introductionmentioning

confidence: 98%

Recent Progress in the Surface Modification of Photoelectrodes toward Efficient and Stable Overall Water Splitting

Kaneko

Minegishi

Domen

2017

Chemistry A European J

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Photoelectrochemical (PEC) water splitting using a combination of a photocathode and photoanode is one of the most promising methods of producing hydrogen from water employing sunlight. Recent reports have shown that surface modification of the photoelectrodes dramatically improves their PEC performance. Bare photoelectrodes often exhibit insufficient depletion regions, undesired surface states and/or degradation due to photocorrosion. It has been demonstrated that surface modifications can tune the flat-band potentials, band-edge potentials, surface states and chemical stabilities of these electrodes and thus improve quantum efficiency, onset potential and durability. This review describes in detail the various surface modification materials that have been developed to date, and the functions of these modifiers. This information is expected to provide guidelines for the future development of photoelectrodes capable of highly efficient and stable PEC water splitting.

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Modeling, Simulation, and Implementation of Solar‐Driven Water‐Splitting Devices

Cited by 132 publications

References 142 publications

Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency

Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency

Possible influence of the Kuramoto length in a photo-catalytic water splitting reaction revealed by Poisson–Nernst–Planck equations involving ionization in a weak electrolyte

Recent Progress in the Surface Modification of Photoelectrodes toward Efficient and Stable Overall Water Splitting

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