Principles and Applications of Semiconductor Photoelectrochemistry

Tan, Ming X.; Laibinis, Paul E.; Nguyen, SonBinh T.; Kesselman, Janet M.; Stanton, Colby E.; Lewis, Nathan S.

doi:10.1002/9780470166420.ch2

Cited by 185 publications

(151 citation statements)

References 272 publications

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“…The data can be fitted with the linear free energy relationship (LFER) [122] shown in the figure (constants in caption). The numerical values of α and β do not have physical significance, because the fitted rate R (μmol h À1 ) does not convey any information about the value of the rate constant for the process, which depends on the electro-active area of the nanoparticles, the absorbed photons flux, space charge layer effects, and other unknown parameters [30,[124][125][126][127][128].The model provides a physical explanation for the observed correlation between nanosheet energetics and hydrogen evolution rates, and it confirms the dependence of photocatalytic activity on the presence of specifically adsorbed ions.…”

Section: Multiple Exciton Generationmentioning

confidence: 99%

Nanoscale Effects in Water Splitting Photocatalysis

Osterloh

2015

Topics in Current Chemistry

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From a conceptual standpoint, the water photoelectrolysis reaction is the simplest way to convert solar energy into fuel. It is widely believed that nanostructured photocatalysts can improve the efficiency of the process and lower the costs. Indeed, nanostructured light absorbers have several advantages over traditional materials. This includes shorter charge transport pathways and larger redox active surface areas. It is also possible to adjust the energetics of small particles via the quantum size effect or with adsorbed ions. At the same time, nanostructured absorbers have significant disadvantages over conventional ones. The larger surface area promotes defect recombination and reduces the photovoltage that can be drawn from the absorber. The smaller size of the particles also makes electron-hole separation more difficult to achieve. This chapter discusses these issues using selected examples from the literature and from the laboratory of the author.

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Section: Multiple Exciton Generationmentioning

confidence: 99%

Nanoscale Effects in Water Splitting Photocatalysis

Osterloh

2015

Topics in Current Chemistry

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“…Once that happens, the equilibrium potential of the electrons in the semiconductor and that of the solution will be the same, and consequently their respective Fermi levels. The key factor allowing semiconductor-electrolyte junctions to separate charge effectively is the electric field present at the interface which can reach the order of 10 5 V/cm 15 . The latter process leads to band bending and the formation of a space charge layer (SCL), which is compensated by a localized Helmholtz layer in the electrolyte.…”

Section: Semiconductor-electrolyte Interfacementioning

confidence: 99%

“…The new band gap, between the false valence band and the original conduction band, is smaller than the original band gap, enhancing the absorption of light in the visible region. Metal ion implantation is referred to as "2 nd generation photocatalyst" 15 . Noble metal loading such as Gold or Silver, Platinum or Palladium, enhances the photo-induced reaction by supporting the electron transfer at the interface, and hindering charge recombination processes in the bulk.…”

Section: Introductionmentioning

confidence: 99%

Capturing Irradiation with Nanoantennae: Plasmon‐Induced Enhancement of Photoelectrolysis

2017

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In solving the energy challenge of solar irradiation′s inconsistency, a desirable approach is mimicking nature′s photosynthesis by collecting and storing solar energy via water splitting. TiO2 is a promising candidate, a wide‐gap semiconductor with low cost, high efficiencies in the UV region, and photostability. Its shortcomings in the visible spectrum can be improved via band gap engineering, mainly co‐catalyst doping, thereof Au nanoparticles. In contrast, we deposit a structured semiconductor on a plasmonic‐active co‐catalyst: we reverse the species order with respect to illumination and achieve a patterned structure for both species in which TiO2 pillars are grown on a Raman‐active Au substrate. The pillars act as antennae, coupling incoming light absorption while feeding on the substrate′s plasmonic effects. The aforementioned system shows impressive incident‐photon‐to‐current efficiencies (IPCEs) in the visible region, along with increased photocurrents in the UV and red shifts depending on deposition depth, diameter, and annealing temperature. We were able to tune the system′s photoresponse by changing the nanostructure geometry and therewith tuned the resonance to the incoming irradiation.

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“…Neither method can be considered environmentally friendly. A more environmentally benign option for hydrogen generation is the use of photoelectrochemical (PEC) cells [1,2]. These cells enable the clean production of hydrogen and oxygen though the photoassisted dissociation of water.…”

Section: Introductionmentioning

confidence: 99%

“…Finding n-type materials that meet these criteria and that also exhibit the chemical stability required to avoid photoanodic dissolution in the PEC cell environment represents the fundamental 2 International Journal of Electrochemistry [9,10]. With a band gap of 3.35 eV [2], ZnO has direct band absorption, and it exhibits ntype semiconducting characteristics even when doped-due to the presence of defects such as Zn on O antisites and oxygen vacancies that are formed during growth [11]. The photoanodic instability of ZnO in aqueous electrolytes [12,13] has been noted previously.…”

Section: Introductionmentioning

confidence: 99%

Photoelectrochemical Stability and Alteration Products of n-Type Single-Crystal ZnO Photoanodes

Paulauskas

Jellison

Boatner

et al. 2011

International Journal of Electrochemistry

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The photoelectrochemical stability and surface-alteration characteristics of doped and undoped n-type ZnO single-crystal photoanode electrodes were investigated. The single-crystal ZnO photoanode properties were analyzed using current-voltage measurements plus spectral and time-dependent quantum-yield methods. These measurements revealed a distinct anodic peak and an accompanying cathodic surface degradation process at negative potentials. The features of this peak depended on time and the NaOH concentration in the electrolyte, but were independent of the presence of electrode illumination. Current measurements performed at the peak indicate that charging and discharging effects are apparently taking place at the semiconductor/electrolyte interface. This result is consistent with the significant reactive degradation that takes place on the ZnO single crystal photoanode surface and that ultimately leads to the reduction of the ZnO surface to Zn metal. The resulting Zn-metal reaction products create unusual, dendrite-like, surface alteration structural features that were analyzed using x-ray diffraction, energy-dispersive analysis, and scanning electron microscopy. ZnO doping methods were found to be effective in increasing the n-type character of the crystals. Higher doping levels result in smaller depletion widths and lower quantum yields, since the minority carrier diffusion lengths are very short in these materials.

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Principles and Applications of Semiconductor Photoelectrochemistry

Cited by 185 publications

References 272 publications

Nanoscale Effects in Water Splitting Photocatalysis

Nanoscale Effects in Water Splitting Photocatalysis

Capturing Irradiation with Nanoantennae: Plasmon‐Induced Enhancement of Photoelectrolysis

Photoelectrochemical Stability and Alteration Products of n-Type Single-Crystal ZnO Photoanodes

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