Dynamics of photogenerated holes in surface modified α-Fe
            <sub>2</sub>
            O
            <sub>3</sub>
            photoanodes for solar water splitting

Barroso, Mónica; Mesa, Camilo A.; Pendlebury, Stephanie R.; Cowan, Alexander J.; Hisatomi, Takashi; Sivula, Kevin; Grätzel, Michaël; Klug, David R.; Durrant, James R.

doi:10.1073/pnas.1118326109

Cited by 425 publications

(494 citation statements)

References 48 publications

Supporting

Mentioning

444

Contrasting

Order By: Relevance

“…Both samples showed a stable photocurrent for 20 min, demonstrating that the Co-Pi co-catalyst modified using our method was effective in preventing self-oxidation of the Ta 3 N 5 and Ba-Ta 3 N 5 nanorods. Recently, there has been some debate about whether Co-Pi acts as a catalyst or spectator [36][37][38] . We believe that in our case the Co-Pi functions as a catalyst because otherwise self-oxidation would result if the water oxidation occurred on the Ta 3 N 5 or Ba-Ta 3 N 5 sites.…”

Section: Resultsmentioning

confidence: 99%

Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency

et al. 2013

View full text Add to dashboard Cite

Spurred by the decreased availability of fossil fuels and global warming, the idea of converting solar energy into clean fuels has been widely recognized. Hydrogen produced by photoelectrochemical water splitting using sunlight could provide a carbon dioxide lean fuel as an alternative to fossil fuels. A major challenge in photoelectrochemical water splitting is to develop an efficient photoanode that can stably oxidize water into oxygen. Here we report an efficient and stable photoanode that couples an active barium-doped tantalum nitride nanostructure with a stable cobalt phosphate co-catalyst. The effect of barium doping on the photoelectrochemical activity of the photoanode is investigated. The photoanode yields a maximum solar energy conversion efficiency of 1.5%, which is more than three times higher than that of state-of-the-art single-photon photoanodes. Further, stoichiometric oxygen and hydrogen are stably produced on the photoanode and the counter electrode with Faraday efficiency of almost unity for 100 min.

show abstract

Section: Resultsmentioning

confidence: 99%

Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Long lived excitons are desirable to ensure e -/h + dissociation before exciton recombination as observed for several metal oxide photoanodes where hole lifetimes ranging from hundreds of milliseconds to seconds are required in order to allow water oxidation. 60 The comparison of the UV-Vis spectra recorded for a bulk heterojunction electrode before and To qualitatively determine the amount of oxygen evolved during a PEC reaction the bulk heterojunction electrode was placed in a fully degassed cell under the application of a positive external bias, irradiated at 1sun (100 mW cm -2 ) at a constant temperature of 298 K and the amount of dissolved oxygen gas was measured using a polarographic electrode. The 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 1 2 3 4 5 6...…”

Section: Xps Characterization Before and After Photoelectrochemical Tmentioning

confidence: 99%

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

et al. 2017

View full text Add to dashboard Cite

The solar-assisted oxidation of water is an essential half reaction for achieving a complete cycle of water splitting. nanosheets results in a 10-fold increase in incident-photon-to-current-efficiency compared to the individual constituents. This proves that charge carrier lifetime is tailorable in atomically thin crystals by creating heterojunctions of different compositions and architectures. Our results suggest that the MoS 2 and WS 2 nanosheets and their bulk heterojunction blend are interesting photocatalytic systems for water oxidation, which can be coupled with different reduction processes for solar-fuel production.

show abstract

“…It is well-known that the presence of an electric field in the space charge region improves charge separation in the active layer, which can enhance the fuel production efficiency. 12 In the model below, we address the question of trap occupation and charge transfer from the surface states, depending on the homogeneous electrode potential. The same model could be formulated for a surface Schottky barrier with simple modifications, but these considerations are beyond the scope of this work.…”

Section: Irect Transformation Of Solar Energy Into Chemical Energymentioning

confidence: 99%

Interpretation of Cyclic Voltammetry Measurements of Thin Semiconductor Films for Solar Fuel Applications

Bertoluzzi

Badia-Bou

Fabregat‐Santiago

et al. 2013

J. Phys. Chem. Lett.

View full text Add to dashboard Cite

A simple model is proposed that allows interpretation of the cyclic voltammetry diagrams obtained experimentally for photoactive semiconductors with surface states or catalysts used for fuel production from sunlight. When the system is limited by charge transfer from the traps/catalyst layer and by detrapping, it is shown that only one capacitive peak is observable and is not recoverable in the return voltage scan. If the system is limited only by charge transfer and not by detrapping, two symmetric capacitive peaks can be observed in the cathodic and anodic directions. The model appears as a useful tool for the swift analysis of the electronic processes that limit fuel production. SECTION:Energy Conversion and Storage; Energy and Charge Transport D irect transformation of solar energy into chemical energy by hydrogen production through water splitting with semiconductor materials in a photoelectrochemical cell constitutes an attractive solution to our energy needs. However, despite the intense efforts carried out in the last decades, no single material has been identified satisfying all of the efficiency, stability, and cost conditions needed for industrial deployment of this technology. 1−4 Hematite (α-Fe 2 O 3 ) has emerged as a promising candidate 5−9 due to its abundance in the earth crust, visible light absorption, and good stability in the harsh environmental conditions needed for operation, although the obtained solarto-fuel efficiencies still remain low for commercial exploitation. One of the main causes of the low performance of hematite is related to the large overpotentials required for water oxidation (around 500 mV), and surface treatments have proven to enhance notably water splitting performances. 10−12 It has been suggested that the reasons for these large overpotentials are related to sluggish hole transfer to the electrolyte 13,14 and to the existence of traps in the bulk and at the semiconductor/ electrolyte interface, 15−17 leading to high recombination. 18,19 Clearly, the separation of the different processes that constitute the oxidative current and the identification of the main kinetic bottlenecks are complex tasks. Therefore, the accurate interpretation of the results provided by characterization techniques constitutes a key tool to rationalize materials development and device optimization. Recently, we have proposed a simple physical model that allows the interpretation of impedance spectroscopy (IS) spectra for water splitting applications. 20 In this model, we have considered a monoenergetic level of surface states where both electron and holes can recombine or transfer from/to the solution.In the present study, we propose a complementary simple model to predict the curves obtained by cyclic voltammetry (CV). This characterization technique allows a quick test of the faradic behavior associated with charge transfer and the capacitive behavior associated with the separated modes of carrier storage, which depend on the thermodynamics and kinetics of the system at stake. 21 ...

show abstract

Dynamics of photogenerated holes in surface modified α-Fe ₂ O ₃ photoanodes for solar water splitting

Cited by 425 publications

References 48 publications

Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency

Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation

Interpretation of Cyclic Voltammetry Measurements of Thin Semiconductor Films for Solar Fuel Applications

Contact Info

Product

Resources

About

Dynamics of photogenerated holes in surface modified α-Fe 2 O 3 photoanodes for solar water splitting

Cited by 425 publications

References 48 publications

Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency

Cobalt phosphate-modified barium-doped tantalum nitride nanorod photoanode with 1.5% solar energy conversion efficiency

MoS2/WS2 Heterojunction for Photoelectrochemical Water Oxidation

Interpretation of Cyclic Voltammetry Measurements of Thin Semiconductor Films for Solar Fuel Applications

Contact Info

Product

Resources

About

Dynamics of photogenerated holes in surface modified α-Fe ₂ O ₃ photoanodes for solar water splitting

MoS₂/WS₂ Heterojunction for Photoelectrochemical Water Oxidation