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Title: Photocatalysis versus photosynthesis: A sensitivity analysis of devices for solar energy conversion and chemical transformations

Here, the chemical literature often does not differentiate between photocatalytic (PC) and photosynthetic (PS) processes (including artificial photosynthesis) even though these reactions differ in their thermodynamics. Photocatalytic processes are thermodynamically downhill (ΔG < 0) and are merely accelerated by the catalyst, whereas photosynthetic processes are thermodynamically unfavorable (ΔG > 0) and require photochemical energy input to occur. Here we apply this differentiation to analyze the basic functions of PC and PS devices and to formulate design criteria for improved performance. As will be shown, the corresponding devices exhibit distinctly different sensitivities to their functional parameters. For example, under conditions of optimal light absorption, carrier lifetimes, and electrochemical rates, the performance of PCs is limited only by their surface area, while type 1 PS devices are limited by their carrier mobility and mass transport, and type 2 PS devices are limited by electrochemical charge-transfer selectivity. Strategies for the optimization of type 1 and 2 photosynthetic devices and photocatalysts are also discussed.
Authors:
ORCiD logo [1]
  1. Univ. of California, Davis, CA (United States)
Publication Date:
Grant/Contract Number:
SC0001234; SC-0001234
Type:
Published Article
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Volume: 2; Journal Issue: 2; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Research Org:
Univ. of California, Davis, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY
OSTI Identifier:
1341470
Alternate Identifier(s):
OSTI ID: 1345212

Osterloh, Frank E. Photocatalysis versus photosynthesis: A sensitivity analysis of devices for solar energy conversion and chemical transformations. United States: N. p., Web. doi:10.1021/acsenergylett.6b00665.
Osterloh, Frank E. Photocatalysis versus photosynthesis: A sensitivity analysis of devices for solar energy conversion and chemical transformations. United States. doi:10.1021/acsenergylett.6b00665.
Osterloh, Frank E. 2017. "Photocatalysis versus photosynthesis: A sensitivity analysis of devices for solar energy conversion and chemical transformations". United States. doi:10.1021/acsenergylett.6b00665.
@article{osti_1341470,
title = {Photocatalysis versus photosynthesis: A sensitivity analysis of devices for solar energy conversion and chemical transformations},
author = {Osterloh, Frank E.},
abstractNote = {Here, the chemical literature often does not differentiate between photocatalytic (PC) and photosynthetic (PS) processes (including artificial photosynthesis) even though these reactions differ in their thermodynamics. Photocatalytic processes are thermodynamically downhill (ΔG < 0) and are merely accelerated by the catalyst, whereas photosynthetic processes are thermodynamically unfavorable (ΔG > 0) and require photochemical energy input to occur. Here we apply this differentiation to analyze the basic functions of PC and PS devices and to formulate design criteria for improved performance. As will be shown, the corresponding devices exhibit distinctly different sensitivities to their functional parameters. For example, under conditions of optimal light absorption, carrier lifetimes, and electrochemical rates, the performance of PCs is limited only by their surface area, while type 1 PS devices are limited by their carrier mobility and mass transport, and type 2 PS devices are limited by electrochemical charge-transfer selectivity. Strategies for the optimization of type 1 and 2 photosynthetic devices and photocatalysts are also discussed.},
doi = {10.1021/acsenergylett.6b00665},
journal = {ACS Energy Letters},
number = 2,
volume = 2,
place = {United States},
year = {2017},
month = {1}
}