Spatioselective Electrochemical and Photoelectrochemical Functionalization of Silicon Microwires with Axial p/n Junctions

Milbrat, Alexander; Elbersen, Rick; Kaş, Recep; Tiggelaar, Roald M.; Gardeniers, Han; Mul, Guido; Huskens, Jurriaan

doi:10.1002/adma.201504609

Cited by 14 publications

(11 citation statements)

References 31 publications

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“…Figure A shows that the good photocurrent reproducibility can be observed in TiO 2 NBs and TiO 2 homojunction. And compared with that of TiO 2 NBs, TiO 2 homojunction exhibits a higher photocurrent intensity indicating that the TiO 2 homojunction catalyst possesses a superior charge separation property and transfer ability, which is consistent with the result of PL analysis. The weak PL intensity and enhanced photocurrent in TiO 2 homojunction further confirmed that the high efficiency of this dendritic homojunction structure on suspension of photo‐generated carrier recombination and promotion of carrier transportation with the simulated solar light irradiation.…”

Section: Resultssupporting

confidence: 82%

Design and constructing of mutually independent crystal facet exposed TiO₂homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Liu

Song

et al. 2018

Int J Energy Res

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Summary Constructing homojunctions of same semiconductors is an effective way to promote charge separation and thus to improve the photoelectrochemical (PEC) and photocatalytic H2 generation performance, and specifically, crystal‐facet exposed homojunction is considered as a very promising structure. Herein, a mutually independent crystal facet exposed TiO2 homojunction was fabricated through a two‐step hydrothermal method with the consideration of morphology and built‐in compacted bonding interaction for PEC water splitting. The as‐prepared homojunction photocatalyst is composed of a similarly dendritic structure where the trunk is TiO2 nanobelts (NBs) array with exposed (101) facets, and the branch portion is ultrathin TiO2 nanosheets (NSs) with exposed (100) facets sequentially located on the side surface of TiO2 NBs. The one‐dimension (1‐D) TiO2 NBs provide a fast electron transfer pathway and are beneficial to the radial transmission of photo‐generated carriers. And the ultrathin TiO2 NSs with a larger surface area can increase direct contact area with electrolyte, light‐harvesting capability and then accelerate the water splitting process. Moreover, due to built‐in compacted bonding interaction between two building blocks with mutually independent exposed facets and matched band structure, this unique homojunction structure can effectively accelerate the transmission of electrons and decrease the recombination rate of the photo‐generated carriers at the interface of two building blocks, thereby increasing the separation efficiency of photo‐generated carriers and simultaneously enhancing the density of photo‐generated electrons and holes, which can be verified through the photocurrent responses and photoluminescence spectra of the as‐prepared samples. As a result, the as‐prepared TiO2 homojunction can not only increase adsorption and profoundly boost photocatalytic performance for decomposition of organic contaminants (rhodamine B), but also possess a higher PEC and photocatalytic H2 generation performance compared with TiO2 NBs. This work offers a new idea to design and fabricate highly efficient TiO2 photocathode for hydrogen generation and degradation of organic pollutants.

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Section: Resultssupporting

confidence: 82%

Design and constructing of mutually independent crystal facet exposed TiO₂homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Liu

Song

et al. 2018

Int J Energy Res

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“…Other reported results strengthen this hypothesis. In earlier work, we have observed an inversed gradient of electrodeposited Pt particles from a solution containing H 2 PtCl 6 on an array of microwires (with 7 μm length, 4 μm diameter and 2 μm spacing). There, the deposited Pt particle density was also higher at the bottom than the top.…”

Section: Results and Discussionmentioning

confidence: 95%

Integration of Molybdenum-Doped, Hydrogen-Annealed BiVO₄ with Silicon Microwires for Photoelectrochemical Applications

Milbrat

Vijselaar

Guo

et al. 2019

ACS Sustainable Chem. Eng.

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H-BiVO4–x:Mo was successfully deposited on microwire-structured silicon substrates, using indium tin oxide (ITO) as an interlayer and BiOI prepared by electrodeposition as precursor. Electrodeposition of BiOI, induced by the electrochemical reduction of p-benzoquinone, appeared to proceed through three stages, being nucleation of particles at the base and bottom of the microwire arrays, followed by rapid (homogeneous) growth, and termination by increasing interfacial resistances. Variations in charge density and morphology as a function of spacing of the microwires are explained by (a) variations in mass transfer limitations, most likely associated with the electrochemical reduction of p-benzoquinone, and (b) inhomogeneity in ITO deposition. Unexpectedly, H-BiVO4–x:Mo on microwire substrates (4 μm radius, 4 to 20 μm spacing, and 5 to 16 μm length) underperformed compared to H-BiVO4–x:Mo on flat surfaces in photocatalytic tests employing sulfite (SO32–) oxidation in a KPi buffer solution at pH 7.0. While we cannot exclude optical effects, or differences in material properties on the nanoscale, we predominantly attribute this to detrimental diffusion limitations of the redox species within the internal volume of the microwire arrays, in agreement with existing literature and the observations regarding the electrodeposition of BiOI. Our results may assist in developing high-efficiency PEC devices.

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“…For example, Milbrat et al . have developed a method for the spatioselective functionalization of silicon microwires with axial p‐n junctions . The charges directed by the junction, either in the dark or under illumination, were used to electrochemically deposit silver or platinum NPs in a spatially selective manner.…”

Section: Introductionmentioning

confidence: 99%

Maskless Spatioselective Functionalization of Silicon Nanowires

Veerbeek

Huskens

2018

ChemNanoMat

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Spatioselective functionalization of silicon nanowires was achieved without using a masking material. The designed process combines metal‐assisted chemical etching (MACE) to fabricate silicon nanowires and hydrosilylation to form molecular monolayers. After MACE, a monolayer was formed on the exposed nanowire surfaces. A second MACE step was expected to elongate the nanowires, thus creating two different segments. When monolayers of 1‐undecene or 1‐tetradecyne were formed on the upper segment, however, the second MACE step did not extend the nanowires. In contrast, nanowires functionalized with 1,8‐nonadiyne were elongated, but at an approximately 8 times slower etching rate. The elongation resulted in a contrast difference in high‐resolution scanning electron microscopy (HR‐SEM) images, which indicated the formation of nanowires that were covered with a monolayer only at the top parts. Click chemistry was successfully used for secondary functionalization of the monolayer with azide‐functionalized nanoparticles. The spatioselective presence of 1,8‐nonadiyne gave a threefold higher particle density on the upper segment functionalized with 1,8‐nonadiyne than on the lower segment without monolayer. These results indicate the successful spatioselective functionalization of silicon nanowires fabricated by MACE.

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Spatioselective Electrochemical and Photoelectrochemical Functionalization of Silicon Microwires with Axial p/n Junctions

Cited by 14 publications

References 31 publications

Design and constructing of mutually independent crystal facet exposed TiO₂homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Design and constructing of mutually independent crystal facet exposed TiO₂homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Integration of Molybdenum-Doped, Hydrogen-Annealed BiVO₄ with Silicon Microwires for Photoelectrochemical Applications

Maskless Spatioselective Functionalization of Silicon Nanowires

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Spatioselective Electrochemical and Photoelectrochemical Functionalization of Silicon Microwires with Axial p/n Junctions

Cited by 14 publications

References 31 publications

Design and constructing of mutually independent crystal facet exposed TiO2homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Design and constructing of mutually independent crystal facet exposed TiO2homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Integration of Molybdenum-Doped, Hydrogen-Annealed BiVO4 with Silicon Microwires for Photoelectrochemical Applications

Maskless Spatioselective Functionalization of Silicon Nanowires

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Design and constructing of mutually independent crystal facet exposed TiO₂homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Design and constructing of mutually independent crystal facet exposed TiO₂homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

Integration of Molybdenum-Doped, Hydrogen-Annealed BiVO₄ with Silicon Microwires for Photoelectrochemical Applications