Quantification of the loss mechanisms in emerging water splitting photoanodes through empirical extraction of the spatial charge collection efficiency
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- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division and Joint Center for Artificial Photosynthesis
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division and Joint Center for Artificial Photosynthesis; Technische Universität München (Germany). Walter Schottky Institut and Physik Department
We present that the operando quantification of surface and bulk losses is key to developing strategies for optimizing photoelectrodes and realizing high efficiency photoelectrochemical solar energy conversion systems. This is particularly true for emerging thin film semiconductors, in which photocarrier diffusion lengths, surface and bulk recombination processes, and charge separation and extraction limitations are poorly understood. Insights into mechanisms of efficiency loss can guide strategies for nanostructuring photoelectrodes, engineering interfaces, and incorporating catalysts. However, few experimental methods are available for direct characterization of dominant loss processes under photoelectrochemical operating conditions. In this work, we provide insight into the function and limitations of an emerging semiconductor photoanode, γ-Cu3V2O8, by quantifying the spatial collection efficiency (SCE), which is defined as the fraction of photogenerated charge carriers at each point below the surface that contributes to the measured current. Analyzing SCE profiles at different operating potentials shows that increasing the applied potential primarily acts to reduce surface recombination rather than to increase the thickness of the space charge region under the semiconductor/electrolyte interface. Comparing SCE profiles obtained with and without a sacrificial reagent allows surface losses from electronically active defect states to be distinguished from performance bottlenecks arising from slow reaction kinetics. Combining these insights promotes a complete understanding of the photoanode performance and its potential as a water splitting photoanode. More generally, application of the SCE extraction method can aid in the discovery and evaluation of new materials for solar water splitting devices by providing mechanistic details underlying photocurrent generation and loss.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Chemical Sciences, Geosciences & Biosciences Division
- Grant/Contract Number:
- AC02-05CH11231; SC0004993
- OSTI ID:
- 1477280
- Journal Information:
- Energy & Environmental Science, Vol. 11, Issue 4; ISSN 1754-5692
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
First-principles modeling of GaN(0001)/water interface: Effect of surface charging
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journal | April 2019 |
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