The Cascade Effectiveness of 3-Terminal Tandem Photocathode Architectures as Applied to CO2 Reduction
Cascade catalysis for photoelectrochemical CO2 reduction (CO2R) decouples the overall reaction into sequential steps occurring on separately optimized catalysts (for example, Ag and Cu) between which an intermediate species such as CO is transferred. A 3-terminal tandem (3TT) photovoltaic architecture advantageously holds two different catalytic regions at different potentials under a single illumination source, but its overall efficiency is low. Using a stochastic reaction-diffusion model, we have examined 3TT photocathode design principles, focusing on the coupling of surface chemistry and transport of CO both inside the boundary layer and outward, into the bulk electrolyte. We find that ensuring that the lateral diffusion distance within the boundary layer is short compared to the boundary layer thickness and controlling bulk flow are key, with interdigitated designs showing an overall conversion efficiency improvement by 2 orders of magnitude compared to the side-by-side case without flow. These findings can be adapted for other cascaded architectures.
- Research Organization:
- California Institute of Technology (CalTech), Pasadena, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); National Laboratory of the Rockies (NLR), Golden, CO (United States)
- Sponsoring Organization:
- US Department of Energy; USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC02-05CH11231; AC36-08GO28308; SC0021266
- OSTI ID:
- 3375355
- Report Number(s):
- NLR/JA-5900-96786
- Journal Information:
- ACS Energy Letters, Journal Name: ACS Energy Letters Journal Issue: 5 Vol. 11; ISSN 2380-8195
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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