Title: Photoelectrochemical Properties and Photostabilities of High Surface Area CuBi ₂ O ₄ and Ag-Doped CuBi ₂ O ₄ Photocathodes

Abstract

Here, electrochemical synthesis methods were developed to produce CuBi₂O₄, a promising p-type oxide for use in solar water splitting, as high surface area electrodes with uniform coverage. These methods involved electrodepositing nanoporous Cu/Bi films with a Cu:Bi ratio of 1:2 from dimethyl sulfoxide or ethylene glycol solutions, and thermally oxidizing them to CuBi₂O₄ at 450°C in air. Ag-doped CuBi₂O₄ electrodes were also prepared by adding a trace amount of Ag+ in the plating medium and codepositing Ag with the Cu/Bi films. In the Ag-doped CuBi₂O₄, Ag+ ions substitutionally replaced Bi3+ ions and increased the hole concentration in CuBi₂O₄. As a result, photocurrent enhancements for both O₂ reduction and water reduction were achieved. Furthermore, while undoped CuBi₂O₄ electrodes suffered from anodic photocorrosion during O₂ reduction due to poor hole transport, Ag-doped CuBiO₄ effectively suppressed anodic photocorrosion. The flat-band potentials of CuBi₂O₄ and Ag-doped CuBi₂O₄ electrodes prepared in this study were found to be more positive than 1.3 V vs RHE in a 0.1 M NaOH solution (pH 12.8), which make these photocathodes highly attractive for use in solar hydrogen production. The optimized CuBi₂O₄/Ag-doped CuBi₂O₄ photocathode showed a photocurrent onset for water reduction at 1.1 V vs RHE, achieving a photovoltage highermore » than 1 V for water reduction. The thermodynamic feasibility of photoexcited electrons in the conduction band of CuBi₂O₄ to reduce water was also confirmed by detection of H₂ during photocurrent generation. This study provides new understanding for constructing improved CuBi₂O₄ photocathodes by systematically investigating photocorrosion as well as photoelectrochemical properties of high-quality CuBi₂O₄ and Ag-doped CuBi₂O₄ photoelectrodes for photoreduction of both O₂ and water.« less

Authors:

Kang, Donghyeon ^[1]; Hill, James C. ^[2]; Park, Yiseul ^[1]; Choi, Kyoung-Shin ^[1]

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+ Show Author Affiliations

1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry
2. Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry

Publication Date:

Thu Jun 09 00:00:00 EDT 2016

Research Org.:

Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division

OSTI Identifier:

1328579

Alternate Identifier(s):

OSTI ID: 1438028

Grant/Contract Number:  

SC0008707

Resource Type:

Published Article

Journal Name:

Chemistry of Materials

Additional Journal Information:

Journal Name: Chemistry of Materials Journal Volume: 28 Journal Issue: 12; Journal ID: ISSN 0897-4756

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE