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Si Microwire-Array Photocathodes Decorated with Cu Allow CO₂ Reduction with Minimal Parasitic Absorption of Sunlight

Kempler, Paul A. and Richter, Matthias H. and Cheng, Wen-Hui and Brunschwig, Bruce S. and Lewis, Nathan S. (2020) Si Microwire-Array Photocathodes Decorated with Cu Allow CO₂ Reduction with Minimal Parasitic Absorption of Sunlight. ACS Energy Letters, 5 (8). pp. 2528-2534. ISSN 2380-8195. doi:10.1021/acsenergylett.0c01334.

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High loadings of Cu were integrated on the light-facing side of Si microwire arrays used under simulated sunlight for the photoelectrochemical reduction of CO₂ (aq) to hydrocarbons in 0.10 M KHCO₃ (aq). Radial-junction n⁺p-Si microwire arrays decorated with Cu exhibited absolute photocurrent densities comparable to an uncovered Si surface. Moreover, with respect to a Cu foil electrode, the positive shift in the onset potential for hydrocarbon formation at n⁺p-Si/Cu microwire arrays was equal to or greater than the photovoltage of the semiconductor alone. Selective electrodeposition of Cu on the tips and sidewalls of Si microwires was responsible for the minimal parasitic reflection and absorption exhibited by the catalyst, such that light-limited, absolute current densities >25 mA·cm⁻² were sustained for 48 h under simulated sunlight. Photoelectrodes prepared from semiconductors with low diode quality factors and electrocatalysts with large Tafel slopes are shown to benefit from increased microstructured surface area. Si microwire arrays are thus suitable for photoelectrochemical reactions requiring high loadings of metallic and reflective electrocatalysts.

Item Type:Article
Related URLs:
URLURL TypeDescription
Kempler, Paul A.0000-0003-3909-1790
Richter, Matthias H.0000-0003-0091-2045
Cheng, Wen-Hui0000-0003-3233-4606
Brunschwig, Bruce S.0000-0002-6135-6727
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2020 American Chemical Society. Received: June 21, 2020; Accepted: July 7, 2020; Published: July 7, 2020. This work was supported through the Office of Science of the U.S. Department of Energy (DOE) under award no. DE SC0004993 to the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub. Fabrication of the Si microwire arrays was performed in the Kavli Nanoscience Institute (KNI) at Caltech, and we thank the KNI staff for their assistance during fabrication. XPS data were collected at the Molecular Materials Resource Center of the Beckman Institute. Author Contributions: Si μW sample fabrication, P.A.K.; Cu foil preparation, M.H.R.; investigation, P.A.K., M.H.R., and W.H.C.; writing, P.A.K., M.H.R., B.S.B., and N.S.L.; funding acquisition, N.S.L. and B.S.B.; supervision, N.S.L. and B.S.B. The authors declare no competing financial interest.
Group:JCAP, Kavli Nanoscience Institute
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Issue or Number:8
Record Number:CaltechAUTHORS:20200707-161346609
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Official Citation:Si Microwire-Array Photocathodes Decorated with Cu Allow CO2 Reduction with Minimal Parasitic Absorption of Sunlight. Paul A. Kempler, Matthias H. Richter, Wen-Hui Cheng, Bruce S. Brunschwig, and Nathan S. Lewis. ACS Energy Letters 2020 5 (8), 2528-2534; DOI: 10.1021/acsenergylett.0c01334
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104264
Deposited By: Tony Diaz
Deposited On:07 Jul 2020 23:26
Last Modified:16 Nov 2021 18:30

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