A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes

Jesus M. Velazquez, Jimmy John, Daniel V. Esposito, Adam Pieterick, Ragip Pala, Guofeng Sun, Xinghao Zhou, Zhuangqun Huang, Shane Ardo, Manuel P. Soriaga, Bruce S. Brunschwig, Nathan S Lewis

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The spatial variation in the photoelectrochemical performance for the reduction of an aqueous one-electron redox couple, Ru(NH3)63+/2+, and for the evolution of H2(g) from 0.5 M H2SO4(aq) at the surface of bare or Pt-decorated p-type WSe2 photocathodes has been investigated in situ using scanning photocurrent microscopy (SPCM). The measurements revealed significant differences in the charge-collection performance (quantified by the values of external quantum yields, Φext) on various macroscopic terraces. Local spectral response measurements indicated a variation in the local electronic structure among the terraces, which was consistent with a non-uniform spatial distribution of sub-band-gap states within the crystals. The photoconversion efficiencies of Pt-decorated p-WSe2 photocathodes were greater for the evolution of H2(g) from 0.5 M H2SO4 than for the reduction of Ru(NH3)63+/2+, and terraces that exhibited relatively low values of Φext for the reduction of Ru(NH3)63+/2+ could in some cases yield values of Φext for the evolution of H2(g) comparable to the values of Φext yielded by the highest-performing terraces. Although the spatial resolution of the techniques used in this work frequently did not result in observation of the effect of edge sites on photocurrent efficiency, some edge effects were observed in the measurements; however the observed edge effects differed among edges, and did not appear to determine the performance of the electrodes.

Original languageEnglish
Pages (from-to)164-175
Number of pages12
JournalEnergy and Environmental Science
Volume9
Issue number1
DOIs
Publication statusPublished - Jan 1 2016

Fingerprint

Photocathodes
terrace
probe
Scanning
Photocurrents
edge effect
Quantum yield
Spatial distribution
Electronic structure
Microscopic examination
Energy gap
microscopy
Crystals
electrode
Electrodes
spatial resolution
spatial variation
Electrons
crystal
spatial distribution

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Chemistry
  • Pollution
  • Nuclear Energy and Engineering

Cite this

A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes. / Velazquez, Jesus M.; John, Jimmy; Esposito, Daniel V.; Pieterick, Adam; Pala, Ragip; Sun, Guofeng; Zhou, Xinghao; Huang, Zhuangqun; Ardo, Shane; Soriaga, Manuel P.; Brunschwig, Bruce S.; Lewis, Nathan S.

In: Energy and Environmental Science, Vol. 9, No. 1, 01.01.2016, p. 164-175.

Research output: Contribution to journalArticle

Velazquez, JM, John, J, Esposito, DV, Pieterick, A, Pala, R, Sun, G, Zhou, X, Huang, Z, Ardo, S, Soriaga, MP, Brunschwig, BS & Lewis, NS 2016, 'A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes', Energy and Environmental Science, vol. 9, no. 1, pp. 164-175. https://doi.org/10.1039/c5ee02530c
Velazquez, Jesus M. ; John, Jimmy ; Esposito, Daniel V. ; Pieterick, Adam ; Pala, Ragip ; Sun, Guofeng ; Zhou, Xinghao ; Huang, Zhuangqun ; Ardo, Shane ; Soriaga, Manuel P. ; Brunschwig, Bruce S. ; Lewis, Nathan S. / A scanning probe investigation of the role of surface motifs in the behavior of p-WSe2 photocathodes. In: Energy and Environmental Science. 2016 ; Vol. 9, No. 1. pp. 164-175.
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