Band Engineered Epitaxial 3D GaN-InGaN Core–Shell Rod Arrays as an Advanced Photoanode for Visible-Light-Driven Water Splitting

Caccamo, Lorenzo; Hartmann, Jana; Fàbrega, Cristian; Estradé, S.; Lilienkamp, G.; Prades, Joan Daniel; Hoffmann, Martin; Ledig, Johannes; Wagner, Alexander; Wang, Xue; López‐Conesa, Lluís; Peiró, Francesca; Rebled, J. M.; Wehmann, H.-H.; Daum, W.; Shen, Hao; Waag, A.

doi:10.1021/am4058937

Cited by 72 publications

(61 citation statements)

References 31 publications

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“…In comparison to 2D films, 3D nanorods with subwavelength-scale induce the light-trapping effect [18–21]. When the light is incident on the surface of 3D nanorods, the photons will be reflected back and forth between the nanoscale gaps resulting in an increase of light absorption (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

et al. 2017

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Recently, colored H-doped TiO2 (H-TiO2) has demonstrated enhanced photoelectrochemical (PEC) performance due to its unique crystalline core—disordered shell nanostructures and consequent enhanced conduction behaviors between the core-shell homo-interfaces. Although various hydrogenation approaches to obtain H-TiO2 have been developed, such as high temperature hydrogen furnace tube annealing, high pressure hydrogen annealing, hydrogen-plasma assisted reaction, aluminum reduction and electrochemical reduction etc., there is still a lack of a hydrogenation approach in a controlled manner where all processing parameters (temperature, time and hydrogen flux) were precisely controlled in order to improve the PEC performance of H-TiO2 and understand the physical insight of enhanced PEC performance. Here, we report for the first time a controlled and local rapid thermal annealing (RTA) approach to prepare hydrogenated core-shell H-TiO2 nanorods grown on F:SnO2 (FTO) substrate in order to address the degradation issue of FTO in the typical TiO2 nanorods/FTO system observed in the conventional non-RTA treated approaches. Without the FTO degradation in the RTA approach, we systematically studied the intrinsic relationship between the annealing temperature, structural, optical, and photoelectrochemical properties in order to understand the role of the disordered shell on the improved photoelectrochemical behavior of H-TiO2 nanorods. Our investigation shows that the improvement of PEC performance could be attributed to (i) band gap narrowing from 3.0 to 2.9 eV; (ii) improved optical absorption in the visible range induced by the three-dimensional (3D) morphology and rough surface of the disordered shell; (iii) increased proper donor density; (iv) enhanced electron–hole separation and injection efficiency due to the formation of disordered shell after hydrogenation. The RTA approach developed here can be used as a suitable hydrogenation process for TiO2 nanorods/FTO system for important applications such as photocatalysis, hydrogen generation from water splitting and solar energy conversion.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-017-2105-x) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

et al. 2017

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“…One facile method to tune the bandgap is changing the ratio of In:Ga in In x Ga 1-x N nanostructures, allowing for significant improvements in the ability to harvest photons from sunlight, which has demonstrated great benefits in solar-to-fuel conversion [7][8][9][10][11][12][13] . In addition, the band edges of In x Ga 1-x N straddle the reduction and oxidation potentials of water, leading to a thermodynamically favorable band structure for hydrogen and oxygen generation from water splitting 14 .…”

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Ultrafast Exciton Dynamics in InGaN/GaN and Rh/Cr₂O₃ Nanoparticle-Decorated InGaN/GaN Nanowires

Kibria

et al. 2015

J. Phys. Chem. Lett.

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Ultrafast exciton and charge-carrier dynamics in InGaN/GaN nanowires (NWs) with and without Rh/Cr2O3 nanoparticle (NP) decoration have been investigated using femtosecond transient absorption (TA) techniques with excitation at 415 nm and white-light probe (450-700 nm). By comparing the TA profiles between InGaN/GaN and InGaN/GaN-Rh/Cr2O3 NWs, an additional decay component on the medium time scale (∼50 ps) was identified with Rh/Cr2O3 decoration, which is attributed to interfacial charge transfer from InGaN/GaN NWs to Rh/Cr2O3 NPs, desired for light energy conversion applications. This is consistent with reduced photoluminescence (PL) of the NWs by the Rh/Cr2O3 NPs. A kinetic model was developed to explain the TA results and gain further insight into the exciton and charge-carrier dynamics.

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“…Chakrapani et al reported an evidence of electrochemical 14 In x Ga 1−x N is a semiconductor of interest for different Fermi level pinning at the GaN surface caused by surface applications including light-emitting diodes 3,4 and biosensors. 5 In particular, InGaN has attracted a lot of attention as material 6,7 for photoelectrodes because of its large carrier mobility, high light absorption coefficient, and the ability to tune its band gap by tailoring the indium concentration. 8,9 However, the relative high overpotential of InGaN could hinder its application as photoelectrode.…”

Section: Introductionmentioning

confidence: 99%

Charge Transfer Characteristics of n-type In_0.1Ga_0.9N Photoanode across Semiconductor–Liquid Interface

et al. 2016

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Understanding the mechanisms of charge transfer across the semiconductor/liquid interface is crucial to realize efficient photoelectrochemical devices. Here, the interfacial charge transfer characteristics of n-type In 0.1 Ga 0.9 N photoanodes are investigated and correlated to their photo-activity properties measured in phosphate buffered saline solution (pH 7) under illumination conditions. Cyclic voltammetry measurements show evident photoactivity changes as the number of cycles increases. In particular, the photocurrent density reaches its maximum value after 49 voltammetric cycles; meanwhile, the photocurrent onset potential shifts toward more negative cathodic potentials. Electrochemical impedance measurements reveal that, first, the hole transfer process occurs mainly via localized states at the surface and the photocurrent onset potential is dependent on the energetic position of those states. Therefore, the observed initial photocurrent increase and cathodic shift of the photocurrent onset potential can be attributed to a decrease of the transfer resistance and partial passivation of the states at the surface. On the other hand, a gradual oxidation and corrosion of the InGaN surface arises, causing a consequential decrease of the photocurrent. At this point, the charge transfer process occurs predominantly from the valence band. This work provides a basic understanding of the charge transfer mechanisms across the InGaN/liquid interface which can be used to improve the overall photoanode efficiency.

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Band Engineered Epitaxial 3D GaN-InGaN Core–Shell Rod Arrays as an Advanced Photoanode for Visible-Light-Driven Water Splitting

Cited by 72 publications

References 31 publications

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

Ultrafast Exciton Dynamics in InGaN/GaN and Rh/Cr₂O₃ Nanoparticle-Decorated InGaN/GaN Nanowires

Charge Transfer Characteristics of n-type In_0.1Ga_0.9N Photoanode across Semiconductor–Liquid Interface

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Band Engineered Epitaxial 3D GaN-InGaN Core–Shell Rod Arrays as an Advanced Photoanode for Visible-Light-Driven Water Splitting

Cited by 72 publications

References 31 publications

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

Enhanced Photoelectrochemical Behavior of H-TiO2 Nanorods Hydrogenated by Controlled and Local Rapid Thermal Annealing

Ultrafast Exciton Dynamics in InGaN/GaN and Rh/Cr2O3 Nanoparticle-Decorated InGaN/GaN Nanowires

Charge Transfer Characteristics of n-type In0.1Ga0.9N Photoanode across Semiconductor–Liquid Interface

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Product

Resources

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Ultrafast Exciton Dynamics in InGaN/GaN and Rh/Cr₂O₃ Nanoparticle-Decorated InGaN/GaN Nanowires

Charge Transfer Characteristics of n-type In_0.1Ga_0.9N Photoanode across Semiconductor–Liquid Interface