Stoichiometric and non-stoichiometric tungsten doping effect in bismuth vanadate based photoactive material for photoelectrochemical water splitting

Umesh Prasad, Jyoti Prakash, Bruno Azeredo, Arunachala Mada Kannan

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1 Citation (Scopus)

Abstract

In photoelectrochemical (PEC) water splitting, BiVO4 has attracted attention due to its favorable band gap but it suffers low PEC performance due to poor conductivity. The vast majority of publications on this system has examined doping of stoichiometric composition of tungsten (W) on this system to increase bulk and interfacial conductivity while managing the contaminant generation of crystallographic defects and recombination sites. In this paper, a deep investigation was carried out to examine the effect of non-stoichiometric W doping in BiVO4 system. Stoichiometric and non-stoichiometric W-doped monoclinic BiVO4 (i.e. Bi1-(x+δ)V1-xWx+δO4; BiV1-xWx+δO4 and BiV1-yWyO4; x = 0.008; y = 0.03 and δ = 0.005) were prepared using a facile dip coating technique. The stoichiometric composition contains charge balanced Bi, V and W atoms whereas non-stoichiometric compositions contain excess Bi and excess Bi and W. The non-stoichiometric composition BiV1-xWx+δO4 has shown better photoelectrochemical water splitting performance with respect to other compositions at 1.23 V vs RHE, under one sun illumination of electrode. The XRD and XPS results shows that non-stoichiometric doping with excess Bi or with excess Bi and W can possibly create an environment where V5+ ions are substitutional replaced by W6+ ions without generating other defects. But there was no significant difference in band gap of different compositional samples observed. Further electrochemical impedance technique was used to analyze change in bulk and surface charge mobility with W-doping in BiVO4. The electrochemical impedance analysis showed the presence of low interfacial resistance, lower charge transfer resistance and high charge donor/surface state density for non-stoichiometric composition BiV1-xWx+δO4 electrode. It is evident from and cyclic voltammetry that the addition of excess Bi and W from its stoichiometric quantity efficiently suppressed the formation of hole-electron pair recombination sites. The electrochemical analytical results lead us to believe that the particular non-stoichiometric composition of BiV1-xWx+δO4 can significantly lower trap sites and enhances kinetics of charge transfer, leading to the better photoelectrochemical water splitting performance.

Original languageEnglish (US)
Pages (from-to)262-272
Number of pages11
JournalElectrochimica Acta
Volume299
DOIs
StatePublished - Mar 10 2019

Fingerprint

Tungsten
Bismuth
Doping (additives)
Water
Chemical analysis
Charge transfer
Energy gap
Ions
Defects
Electrodes
Coating techniques
Surface states
Surface charge
bismuth vanadium tetraoxide
Sun
Cyclic voltammetry
X ray photoelectron spectroscopy
Lighting
Impurities
Atoms

Keywords

  • Bismuth vanadate
  • Oxygen evolution
  • Photoelectrochemical cell
  • Tungsten doping
  • Water splitting

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry

Cite this

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title = "Stoichiometric and non-stoichiometric tungsten doping effect in bismuth vanadate based photoactive material for photoelectrochemical water splitting",
abstract = "In photoelectrochemical (PEC) water splitting, BiVO4 has attracted attention due to its favorable band gap but it suffers low PEC performance due to poor conductivity. The vast majority of publications on this system has examined doping of stoichiometric composition of tungsten (W) on this system to increase bulk and interfacial conductivity while managing the contaminant generation of crystallographic defects and recombination sites. In this paper, a deep investigation was carried out to examine the effect of non-stoichiometric W doping in BiVO4 system. Stoichiometric and non-stoichiometric W-doped monoclinic BiVO4 (i.e. Bi1-(x+δ)V1-xWx+δO4; BiV1-xWx+δO4 and BiV1-yWyO4; x = 0.008; y = 0.03 and δ = 0.005) were prepared using a facile dip coating technique. The stoichiometric composition contains charge balanced Bi, V and W atoms whereas non-stoichiometric compositions contain excess Bi and excess Bi and W. The non-stoichiometric composition BiV1-xWx+δO4 has shown better photoelectrochemical water splitting performance with respect to other compositions at 1.23 V vs RHE, under one sun illumination of electrode. The XRD and XPS results shows that non-stoichiometric doping with excess Bi or with excess Bi and W can possibly create an environment where V5+ ions are substitutional replaced by W6+ ions without generating other defects. But there was no significant difference in band gap of different compositional samples observed. Further electrochemical impedance technique was used to analyze change in bulk and surface charge mobility with W-doping in BiVO4. The electrochemical impedance analysis showed the presence of low interfacial resistance, lower charge transfer resistance and high charge donor/surface state density for non-stoichiometric composition BiV1-xWx+δO4 electrode. It is evident from and cyclic voltammetry that the addition of excess Bi and W from its stoichiometric quantity efficiently suppressed the formation of hole-electron pair recombination sites. The electrochemical analytical results lead us to believe that the particular non-stoichiometric composition of BiV1-xWx+δO4 can significantly lower trap sites and enhances kinetics of charge transfer, leading to the better photoelectrochemical water splitting performance.",
keywords = "Bismuth vanadate, Oxygen evolution, Photoelectrochemical cell, Tungsten doping, Water splitting",
author = "Umesh Prasad and Jyoti Prakash and Bruno Azeredo and {Mada Kannan}, Arunachala",
year = "2019",
month = "3",
day = "10",
doi = "10.1016/j.electacta.2019.01.013",
language = "English (US)",
volume = "299",
pages = "262--272",
journal = "Electrochimica Acta",
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publisher = "Elsevier Limited",

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TY - JOUR

T1 - Stoichiometric and non-stoichiometric tungsten doping effect in bismuth vanadate based photoactive material for photoelectrochemical water splitting

AU - Prasad, Umesh

AU - Prakash, Jyoti

AU - Azeredo, Bruno

AU - Mada Kannan, Arunachala

PY - 2019/3/10

Y1 - 2019/3/10

N2 - In photoelectrochemical (PEC) water splitting, BiVO4 has attracted attention due to its favorable band gap but it suffers low PEC performance due to poor conductivity. The vast majority of publications on this system has examined doping of stoichiometric composition of tungsten (W) on this system to increase bulk and interfacial conductivity while managing the contaminant generation of crystallographic defects and recombination sites. In this paper, a deep investigation was carried out to examine the effect of non-stoichiometric W doping in BiVO4 system. Stoichiometric and non-stoichiometric W-doped monoclinic BiVO4 (i.e. Bi1-(x+δ)V1-xWx+δO4; BiV1-xWx+δO4 and BiV1-yWyO4; x = 0.008; y = 0.03 and δ = 0.005) were prepared using a facile dip coating technique. The stoichiometric composition contains charge balanced Bi, V and W atoms whereas non-stoichiometric compositions contain excess Bi and excess Bi and W. The non-stoichiometric composition BiV1-xWx+δO4 has shown better photoelectrochemical water splitting performance with respect to other compositions at 1.23 V vs RHE, under one sun illumination of electrode. The XRD and XPS results shows that non-stoichiometric doping with excess Bi or with excess Bi and W can possibly create an environment where V5+ ions are substitutional replaced by W6+ ions without generating other defects. But there was no significant difference in band gap of different compositional samples observed. Further electrochemical impedance technique was used to analyze change in bulk and surface charge mobility with W-doping in BiVO4. The electrochemical impedance analysis showed the presence of low interfacial resistance, lower charge transfer resistance and high charge donor/surface state density for non-stoichiometric composition BiV1-xWx+δO4 electrode. It is evident from and cyclic voltammetry that the addition of excess Bi and W from its stoichiometric quantity efficiently suppressed the formation of hole-electron pair recombination sites. The electrochemical analytical results lead us to believe that the particular non-stoichiometric composition of BiV1-xWx+δO4 can significantly lower trap sites and enhances kinetics of charge transfer, leading to the better photoelectrochemical water splitting performance.

AB - In photoelectrochemical (PEC) water splitting, BiVO4 has attracted attention due to its favorable band gap but it suffers low PEC performance due to poor conductivity. The vast majority of publications on this system has examined doping of stoichiometric composition of tungsten (W) on this system to increase bulk and interfacial conductivity while managing the contaminant generation of crystallographic defects and recombination sites. In this paper, a deep investigation was carried out to examine the effect of non-stoichiometric W doping in BiVO4 system. Stoichiometric and non-stoichiometric W-doped monoclinic BiVO4 (i.e. Bi1-(x+δ)V1-xWx+δO4; BiV1-xWx+δO4 and BiV1-yWyO4; x = 0.008; y = 0.03 and δ = 0.005) were prepared using a facile dip coating technique. The stoichiometric composition contains charge balanced Bi, V and W atoms whereas non-stoichiometric compositions contain excess Bi and excess Bi and W. The non-stoichiometric composition BiV1-xWx+δO4 has shown better photoelectrochemical water splitting performance with respect to other compositions at 1.23 V vs RHE, under one sun illumination of electrode. The XRD and XPS results shows that non-stoichiometric doping with excess Bi or with excess Bi and W can possibly create an environment where V5+ ions are substitutional replaced by W6+ ions without generating other defects. But there was no significant difference in band gap of different compositional samples observed. Further electrochemical impedance technique was used to analyze change in bulk and surface charge mobility with W-doping in BiVO4. The electrochemical impedance analysis showed the presence of low interfacial resistance, lower charge transfer resistance and high charge donor/surface state density for non-stoichiometric composition BiV1-xWx+δO4 electrode. It is evident from and cyclic voltammetry that the addition of excess Bi and W from its stoichiometric quantity efficiently suppressed the formation of hole-electron pair recombination sites. The electrochemical analytical results lead us to believe that the particular non-stoichiometric composition of BiV1-xWx+δO4 can significantly lower trap sites and enhances kinetics of charge transfer, leading to the better photoelectrochemical water splitting performance.

KW - Bismuth vanadate

KW - Oxygen evolution

KW - Photoelectrochemical cell

KW - Tungsten doping

KW - Water splitting

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U2 - 10.1016/j.electacta.2019.01.013

DO - 10.1016/j.electacta.2019.01.013

M3 - Article

VL - 299

SP - 262

EP - 272

JO - Electrochimica Acta

JF - Electrochimica Acta

SN - 0013-4686

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