Discovery and Characterization of a Pourbaix-Stable, 1.8 eV Direct Gap Bismuth Manganate Photoanode
Abstract
Solar-driven oxygen evolution is a critical technology for renewably synthesizing hydrogen- and carbon-containing fuels in solar fuel generators. New photoanode materials are needed to meet efficiency and stability requirements, motivating materials explorations for semiconductors with (i) band-gap energy in the visible spectrum and (ii) stable operation in aqueous electrolyte at the electrochemical potential needed to evolve oxygen from water. Motivated by the oxygen evolution competency of many Mn-based oxides, the existence of several Bi-containing ternary oxide photoanode materials, and the variety of known oxide materials combining these elements with Sm, we explore the Bi–Mn–Sm oxide system for new photoanodes. Through the use of a ferri/ferrocyanide redox couple in high-throughput screening, BiMn_2O_5 and its alloy with Sm are identified as photoanode materials with a near-ideal optical band gap of 1.8 eV. Using density functional theory-based calculations of the mullite Bi^(3+)Mn^(3+)Mn^(4+)O_5 phase, we identify electronic analogues to the well-known BiVO4 photoanode and demonstrate excellent Pourbaix stability above the oxygen evolution Nernstian potential from pH 4.5 to 15. Our suite of experimental and computational characterization indicates that BiMn_2O_5 is a complex oxide with the necessary optical and chemical properties to be an efficient, stable solar fuel photoanode.
Additional Information
© 2017 American Chemical Society. Received: August 25, 2017; Revised: November 13, 2017; Published: November 13, 2017. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy (Award DE-SC0004993). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract DE-AC02-76SF00515. Pourbaix diagram computation was supported by the Materials Project (BES DOE Grant EDCBEE). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract DE-AC02-05CH11231. We thank Apurva Mehta, Fang Ren, Douglas G. Van Campen, Tim Dunn, and Ryan Jones for assistance with collection of synchrotron XRD data. The authors declare no competing financial interest.Attached Files
Supplemental Material - acs.chemmater.7b03591.pdf
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Additional details
- Eprint ID
- 83218
- Resolver ID
- CaltechAUTHORS:20171115-095753143
- Department of Energy (DOE)
- DE-SC0004993
- Department of Energy (DOE)
- DE-AC02-76SF00515
- Department of Energy (DOE)
- DE-AC02-05CH11231
- Created
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2017-11-15Created from EPrint's datestamp field
- Updated
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2021-11-15Created from EPrint's last_modified field
- Caltech groups
- JCAP