Arc Synthesis, Crystal Structure, and Photoelectrochemistry of Copper(I) Tungstate
Tayar Galante, Miguel; Zivkovic, A.; Costa Alvim, Jéssica; Cristina Calchi Kleiner, Cinthia; Sangali, Márcio; Taylor, S.F. Rebecca; Greer, Adam J.; Hardacre, Christopher; Rajeshwar, Krishnan; Caram, Rubens; Bertazzoli, Rodnei; Macaluso, Robin T.; de Leeuw, Nora H.; Longo, Claudia
(2021) ACS applied materials & interfaces, volume 13, issue 28, pp. 32865 - 32875
(Article)
Abstract
A little-studied p-type ternary oxide semiconductor, copper(I) tungstate (Cu2WO4), was assessed by a combined theoretical/experimental approach. A detailed computational study was performed to solve the long-standing debate on the space group of Cu2WO4, which was determined to be triclinic P1. Cu2WO4 was synthesized by a time-efficient, arc-melting method, and the
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crystalline reddish particulate product showed broad-band absorption in the UV–visible spectral region, thermal stability up to ∼260 °C, and cathodic photoelectrochemical activity. Controlled thermal oxidation of copper from the Cu(I) to Cu(II) oxidation state showed that the crystal lattice could accommodate Cu2+ cations up to ∼260 °C, beyond which the compound was converted to CuO and CuWO4. This process was monitored by powder X-ray diffraction and X-ray photoelectron spectroscopy. The electronic band structure of Cu2WO4 was contrasted with that of the Cu(II) counterpart, CuWO4 using spin-polarized density functional theory (DFT). Finally, the compound Cu2WO4 was determined to have a high-lying (negative potential) conduction band edge underlining its promise for driving energetic photoredox reactions.
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Keywords: arc synthesis, copper tungstate, crystal structure, density functional theory, p-type semiconductor, photoelectrochemistry, solar fuels, ternary copper oxide, General Materials Science
ISSN: 1944-8244
Publisher: American Chemical Society
Note: Funding Information: The authors gratefully acknowledge Dr. Flavia Cassiola and her team at Shell Technologies Center Houston for the valuable support in SEM analyses. M.T.G., J.C.A., and C.L. acknowledge support from National Council for Scientific and Technological Development (CNPq), Unicamp Fund for Support to Teaching, Research and Outreach Activities (FAEPEX Unicamp/Cardiff Mobility program), CAPES-PrInt Program (Process 88881.310535/2018-01), FAPESP (the São Paulo Research Foundation, Processes 2017/11986-5) and Shell and the strategic importance of the support given by ANP (Brazil’s National Oil, Natural Gas and Biofuels Agency) through the R&D levy regulation. R.B. also acknowledges the support from FAPESP, Process 2019/11353-8. C.H., R.T., A.G., and N.H.d.L. acknowledge funding from the EPSRC under grant no. EP/N009533/1, Multi-Disciplinary Approach to Generating Low Carbon Fuels, carried out in collaboration with the University of Manchester, Queen’s University Belfast, Cardiff University, and University College London. Open access data can be found via the University of Manchester research portal. A.Z. and N.H.d.L. acknowledge the NWO ECHO grant (712.018.005) for funding. The computational work was carried out on the Dutch national e-infrastructure with the support of the SURF Cooperative. The authors thank the four anonymous reviewers for constructive criticisms of an earlier manuscript version. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society.
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