Marked enhancement in electron–hole separation achieved in the low bias region using electrochemically prepared Mo-doped BiVO<sub>4</sub>photoanodes

Park, Yiseul; Kang, Dong Hyun; Choi, Kyoung‐Shin

doi:10.1039/c3cp53649a

Cited by 125 publications

(148 citation statements)

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“…This suggests that the FeOOH layer induced the photostability of BiVO 4 /FeOOH. The use of FeOOH has been replicated in other studies for these reasons [29,42].…”

Section: Strategies Adopted To Enhance Reaction Kinetics In Solar Watsupporting

confidence: 50%

“…Park et al [42] reported that 3 at.% Mo doping on the V site almost doubled the absorbed photon-to-current efficiency (APCE), and also significantly enhanced the photocurrent density of bare BiVO 4 , from between 0.1 and 0.2 mA/cm 2 at 1.23 V vs. RHE, reaching a final photocurrent density of up to 1.0 mA/cm 2 at 1.23 V vs. RHE. After addition of an FeOOH OER co-catalyst, the photocurrent density increased even more to 3 mA/cm 2 at 1.23 V vs. RHE.…”

Section: Addition Of N-type Conductivity Dopantsmentioning

confidence: 99%

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Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

2017

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Photoelectrochemical (PEC) water splitting, which is a type of artificial photosynthesis, is a sustainable way of converting solar energy into chemical energy. The water oxidation half-reaction has always represented the bottleneck of this process because of the thermodynamic and kinetic challenges that are involved. Several materials have been explored and studied to address the issues pertaining to solar water oxidation. Significant advances have recently been made in the use of stable and relatively cheap metal oxides, i.e., semiconducting photocatalysts. The use of BiVO 4 for this purpose can be considered advantageous because this catalyst is able to absorb a substantial portion of the solar spectrum and has favourable conduction and valence band edge positions. However, BiVO 4 is also associated with poor electron mobility and slow water oxidation kinetics and these are the problems that are currently being investigated in the ongoing research in this field. This review focuses on the most recent advances in the best-performing BiVO 4 -based photoanodes to date. It summarizes the critical parameters that contribute to the performance of these photoanodes, and highlights so far unresolved critical features related to the scale-up of a BiVO 4 -based PEC water-splitting device.

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“…This suggests that the FeOOH layer induced the photostability of BiVO 4 /FeOOH. The use of FeOOH has been replicated in other studies for these reasons [29,42].…”

Section: Strategies Adopted To Enhance Reaction Kinetics In Solar Watsupporting

confidence: 50%

Section: Addition Of N-type Conductivity Dopantsmentioning

confidence: 99%

Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

2017

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“…Such Mo-free, textured samples are designated ''noMo/T'' films. To assess the impact of incorporating molybdenum, an impurity known to improve the photocurrent of BiVO 4 electrodes, 18,21,26,30,31,33,34,37,40,42 we added Mo to untextured and textured BVO films (making ''Mo/U'' and ''Mo/T'' films, respectively) by spiking the spin coating solution with 2 at% MoO 2 (acac) 2 (see Experimental and Fig. 1c-e).…”

Section: Resultsmentioning

confidence: 99%

“…21,42 In this paper, we assume Z rxn,sulfite = 100% and negligible current doubling by sulfite. 59 Fig .…”

Section: àmentioning

confidence: 99%

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Nair

Perkins

Lin

et al. 2016

Energy Environ. Sci.

155

106

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We have developed a simple spin coating method to make high-quality nanoporous photoelectrodes of monoclinic BiVO 4 and studied the ability of these electrodes to transport photogenerated carriers to oxidize sulfite and water. Samples containing molybdenum and featuring [001] out-of-plane crystallographic texture show a photocurrent and external quantum efficiency (EQE) for sulfite oxidation as high as 3.1 mA cm À2 and 60%, respectively, at 1.23 V versus reversible hydrogen electrode. By using an optical model of the electrode stack to accurately determine the fraction of electrode absorptance due to the BiVO 4 active layer, we estimate that on average 70 AE 5% of all photogenerated carriers escape recombination. A comparison of internal quantum efficiency as a function of film processing, illumination direction, and film thickness shows that electron transport is efficient and hole transport limits the photocurrent (hole diffusion length o40 nm). We find that Mo addition primarily improves electron transport and texturing mostly improves hole transport. Mo enhances electron transport by thinning the surface depletion layer or passivating traps and recombination centers at grain boundaries and interfaces, while improved hole transport in textured films may result from more efficient lateral hole extraction due to the texturing itself or the reduced density of deep gap states observed in photoemission measurements.Photoemission data also reveal that the films have bismuth-rich, vanadium-and oxygen-deficient surface layers, while ion scattering spectroscopy indicates a Bi-V-O surface termination. Without added catalysts, the plain BiVO 4 electrodes oxidized water with an initial photocurrent and peak EQE of 1.7 mA cm À2 and 30%, respectively, which equates to a hole transfer efficiency to water of 464% at 1.23 V. The electrodes quickly photocorrode during water oxidation but show good stability during sulfite oxidation and indefinite stability in the dark. By improving the hole transport efficiency and coating these nanoporous BiVO 4 films with an appropriate protective layer and oxygen evolution catalyst, it should be possible to achieve highly efficient and stable water oxidation at a practical pH.

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“…8a). 60 Undoubtedly, the separation and transportation of the non-directional electrons are crucial factors for the further suppression on interfacial recombination. For this, given its high conductivity, rGO was introduced into FeOOH/P:BiVO 4 to transfer the electron to FTO (Fig.…”

Section: -50mentioning

confidence: 99%

Enriched Photoelectrochemical Performance of Phosphate Doped BiVO₄Photoelectrode by Coupling FeOOH and rGO

Qiu

Song

Wang

et al. 2017

J. Electrochem. Soc.

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Bismuth vanadate is a promising photoanode with a set of intrinsic limitations for water oxidation and photoelectrochemical degradation of organic pollution. FeOOH/P:BiVO 4 /rGO composite with a considerably small charge-transfer resistance was successfully developed by doping the BiVO 4 lattice with phosphate (P:BiVO 4 ), photo-depositing FeOOH nanoparticles on P:BiVO 4 nanoparticles, and grafting reduced graphene oxide (rGO) onto the surface of P:BiVO 4 , in that order. This composite photoelectrode significantly improves photoelectrochemical performance originating from its effective suppression on electron-hole recombination and charge transfer at the semiconductor/electrolyte interface. The photoelectrocatalysts were systematically characterized by FTIR, XPS, SEM, TEM, UV-vis and XRD. The characterization results show that FeOOH/P:BiVO 4 /rGO consisted of spherical agglomerates comprising a large number of P:BiVO 4 nanoparticles with an average size of approximately 10 nm. FeOOH nanoparticles were successfully loaded onto the surface of P:BiVO 4 nanoparticles, and rGO layers with a thickness of approximately 4 nm were coated onto the P:BiVO 4 particles. The enhanced photoelectrochemical properties were observed using linear sweep voltammetry. The mechanism underlying the observed photoelectrocatalytic activity enhancement was determined using Mott-Schottky analysis and electrochemical impedance spectroscopy. The photocurrent density of FeOOH/P:BiVO 4 /rGO in a Na 2 SO 4 solution with 2,4-dichlorophenol (2,4-DCP) at 0.6 V Ag/AgCl is approximately 100 times higher than that of P:BiVO 4 ; the onset potentials of FeOOH/P:BiVO 4 /rGO (0.008 V Ag/AgCl ) is 5 times lower than that of P:BiVO 4 (0.043 V Ag/AgCl ). It is suggested that FeOOH/P:BiVO 4 /rGO obtains the highest photoelectrocatalytic performance for 2,4-DCP degradation. The proposed mechanism is that the synergistic effect between FeOOH and rGO can alleviate two main limitations of P:BiVO 4 : suppression on the bulk recombination and interfacial recombination formed at the P:BiVO 4 -FeOOH junction and effective charge transfer at the semiconductor/electrolyte interface. Environmental pollution by chlorinated phenols (CPs) has become one of the most important worldwide issues. Because many types of CPs are resistant to physical, chemical, and biological treatment processes, and their accumulation poses a threat to living organisms, including human beings. 1 Many studies have been devoted to developing effective methods to degrade CPs, such as photocatalytic oxidation, 2 photoelectrochemical (PEC) technology, 3 and electrochemical oxidation-reduction. 4 Notably, PEC technology is regarded as not only a promising solution to the increasing energy demand, but also an effective wastewater treatment. Developing a practical and effective photoelectrocatalyst that can be used under moderate reaction conditions, exhibits high degradation efficiency, and requires low energy cost is important. One of the most promising photoanode materials, monoclinic BiVO 4 exhibi...

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Marked enhancement in electron–hole separation achieved in the low bias region using electrochemically prepared Mo-doped BiVO₄photoanodes

Cited by 125 publications

References 32 publications

Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Enriched Photoelectrochemical Performance of Phosphate Doped BiVO₄Photoelectrode by Coupling FeOOH and rGO

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Marked enhancement in electron–hole separation achieved in the low bias region using electrochemically prepared Mo-doped BiVO4photoanodes

Cited by 125 publications

References 32 publications

Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

Recent Advances in the BiVO4 Photocatalyst for Sun-Driven Water Oxidation: Top-Performing Photoanodes and Scale-Up Challenges

Textured nanoporous Mo:BiVO4 photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Enriched Photoelectrochemical Performance of Phosphate Doped BiVO4Photoelectrode by Coupling FeOOH and rGO

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Product

Resources

About

Marked enhancement in electron–hole separation achieved in the low bias region using electrochemically prepared Mo-doped BiVO₄photoanodes

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Enriched Photoelectrochemical Performance of Phosphate Doped BiVO₄Photoelectrode by Coupling FeOOH and rGO