Hand-in-hand quantum dot assembly sensitized photocathodes for enhanced photoelectrochemical hydrogen evolution

Wu, Hao‐Lin; Li, Xu‐Bing; Wang, Yang; Zhou, Shuai; Chen, Yajing; He, Xiao-Jun; Tung, Chen‐Ho; Wu, Li‐Zhu

doi:10.1039/c9ta10056c

Cited by 11 publications

(7 citation statements)

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Section: Qds Assemblymentioning

confidence: 99%

“…However, the sequential deposition of CdSe and CdTe QDs can result in a significant current attenuation because the outer CdTe layers not only hinder electron transfer from the inner CdSe but also limit the PEC performance due to their relatively weak proton reduction capability. To solve this issue, Wu's group introduced a linker molecule between CdSe and CdTe (Figure 9c,d), [235] which can efficiently shorten the interparticle distance, ensuring facile and ultrafast interparticle charge transfer. Such a design also provides a strategy that can adequately handle the spatial orientation of QDs when loaded on the electrode surface.…”

Section: Qds Assemblymentioning

confidence: 99%

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Quantum Dots‐Based Photoelectrochemical Hydrogen Evolution from Water Splitting

Liu

Zhao

Wang

et al. 2021

Advanced Energy Materials

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opportunity since it is by far the most abundant, sustainable, carbon-neutral, and inexpensive energy source. The theoretical potential of solar power striking the earth's surface is ≈89 300 TW (the integral of the time-and-space-averaged solar flux 342.5 W m −2 over the earth's surface area 5.11 × 10 14 m 2 , estimating that ≈30% and ≈19% are scattered and absorbed by the atmosphere and clouds), [3] which is equivalent to ≈6000 times the power used worldwide every year (estimated at 13.5 TW in 2001, with projected growth up to 27.6 TW by 2050 by the Intergovernmental Panel on Climate Change). [4] In particular, storing solar energy in the form of H 2 presents advantages such as high energy content per mass (143 MJ kg −1), ease of transportation, and cost-effectiveness, [5] thereby addressing the storage challenge which is associated with the diffuse and intermittent character of solar irradiation. Solar energy and water could be converted into H 2 [5b] indirectly by using solar-converted electricity and an electrolyzer, [6] concentrated solar thermal and an electrolyzer, [7] biological and thermochemical processes [8] or directly by photo-/photoelectrocatalysis of water. [1b,f,g] The combination of the energy conversion step with electrolyzers is always limited by the performance of the electrolyzers, whose typical commercial efficiencies are around 73%. [9] Besides, indirect technologies suffer from excessive cost, area requirements, feasibility issues, or energy loss. [10] An alternative direct route is the photo-/photoelectrocatalysis of water, including powdered photocatalysts [11] and photoelectrochemical (PEC) cells. [12] The dispersion of powdered photocatalysts in water is suitable for large-scale processes, while the system requires stirring during the reaction and product separation after the reaction. In comparison, PEC systems (Figure 1a), which combine harvesting solar energy with water reduction into a single device, possesses several advantages. [13] i) PEC reactions address the issue of gas separation by generating products at different electrodes. ii) An external bias supply or self-bias voltage in the PEC system can provide additional energy input to compensate for the potential deficiency, [14] leading to the formation of a surface space charge layer and achieving efficient charge separation and an increased number of long-living photogenerated charges. [15] iii) Moreover, PEC systems can potentially be operated using only stable and abundant materials, such as Cu-based metal oxides, [16] Fe 2 O 3 , [14b,17] and TiO 2. [18] In a typical PEC system, at least one photoelectrode is used as a working electrode to harvest solar radiation, either acting Solar-driven photoelectrochemical (PEC) hydrogen evolution is a promising and sustainable approach to convert solar energy into a fuel that can be stored. Semiconductor quantum dots (QDs) are increasingly used in PEC devices due to their broad composition/size/shape tunable absorption spectrum (from ultraviolet to near-infrared, with significant over...

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Section: Qds Assemblymentioning

confidence: 99%

Section: Qds Assemblymentioning

confidence: 99%

Quantum Dots‐Based Photoelectrochemical Hydrogen Evolution from Water Splitting

Liu

Zhao

Wang

et al. 2021

Advanced Energy Materials

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“…Photoelectrochemical (PEC) water splitting has presented great potential in harvesting solar energy to produce hydrogen in an environmentally friendly manner. − The photoelectrode, as the pivotal component in a PEC cell, enables photoinduced carrier excitation, separation, transport, and then drives water reduction/oxidation reactions at the electrode/electrolyte interface. , Therefore, accelerating the photocarrier transport at the interfaces between the host semiconductor photoelectrode and the guest modification species (e.g., the second semiconductor layer, the quantum dot sensitizer, the protective layer and the catalyst layer), as well as at the electrode/electrolyte interface, is essential to achieve highly efficient PEC water splitting. − Given the relatively low maximum photocurrent densities generated by most metal oxide photoelectrodes, because of the wide band gaps and, thus, the limited optical absorption in visible region, it is highly expected to develop semiconductor photoelectrodes with narrow band gaps to ensure the effective use of wide-spectrum sunlight …”

mentioning

confidence: 99%

Building Directional Charge Transport Channel in CdTe-Based Multilayered Photocathode for Efficient Photoelectrochemical Hydrogen Evolution

Chen

Yin

Cao

et al. 2022

ACS Materials Lett.

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Modulating the band alignment of semiconducting photoelectrodes is essential for efficient carrier transport and consequently optimized photoelectrochemical performances. Herein, a CdS/TiO2 bilayer is coated on a CdTe absorber via chemical bath deposition and magnetron sputtering, successively, to build directional interfacial charge transfer channels for efficient photoelectrochemical hydrogen evolution. The obtained multilayered CdTe/CdS/TiO2/Pt photocathode yields a dramatically increased photocurrent density of −9.6 mA cm–2 at −0.4 V vs reversible hydrogen electrode (RHE) under simulated sunlight (AM 1.5 G, 100 mW cm–2). It is well evidenced that, with the CdS/TiO2 bilayer coated onto CdTe, the CdTe/CdS/TiO2 heterojunction, with a well aligned band structure, generates favorable conduction band offset, energetically facilitating electron transfer from CdTe to CdS, and then to TiO2. Moreover, the CdTe/CdS/TiO2/Pt photocathode shows good stability for water reduction due to the TiO2 protective layer stabilizing against the photocorrosion of CdTe/CdS. This study provides referable guidance for designing multilayer photoelectrodes for stable and efficient solar water splitting from the viewpoint of interface energetics engineering.

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“…In this process, hydrogen and oxygen are generated through the decomposition of water because of the photochemical reaction started by the semiconductor aer the adsorption of sunlight. [72][73][74][75][76][77] The PEC water splitting process is one of the most promising methods to convert light energy into chemical energy. The main challenge in the PEC system is to nd a suitable material with absorption in a broad range of the solar spectrum, high photochemical stability, a suitable band edge position, low overpotential, efficient use in photogenerated electron-hole pairs, and low cost.…”

Section: Photocatalytic Water Splittingmentioning

confidence: 99%