期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 113, 期 42, 页码 11750-11755出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1610554113
关键词
energy conversion; spectroscopy; CO2 reduction; biohybrid systems; catalysis
资金
- Office of Science, Office of Basic Energy Sciences, of the US Department of Energy (DOE) [DE-AC02-05CH11231]
- National Science Foundation [DMR-1507914]
- Office of Science, Office of Basic Energy Sciences, of the US DOE [DE-AC02-05CH11231]
- Direct For Mathematical & Physical Scien [1507914] Funding Source: National Science Foundation
- Division Of Chemistry
- Direct For Mathematical & Physical Scien [1213135] Funding Source: National Science Foundation
- Division Of Materials Research [1507914] Funding Source: National Science Foundation
The rise of inorganic-biological hybrid organisms for solar-to-chemical production has spurred mechanistic investigations into the dynamics of the biotic-abiotic interface to drive the development of next-generation systems. The model system, Moorella thermoacetica-cadmium sulfide (CdS), combines an inorganic semiconductor nanoparticle light harvester with an acetogenic bacterium to drive the photosynthetic reduction of CO2 to acetic acid with high efficiency. In this work, we report insights into this unique electrotrophic behavior and propose a charge-transfer mechanism from CdS to M. thermoacetica. Transient absorption (TA) spectroscopy revealed that photoexcited electron transfer rates increase with increasing hydrogenase (H(2)ase) enzyme activity. On the same time scale as the TA spectroscopy, time-resolved infrared (TRIR) spectroscopy showed spectral changes in the 1,700-1,900-cm(-1) spectral region. The quantum efficiency of this system for photosynthetic acetic acid generation also increased with increasing H(2)ase activity and shorter carrier lifetimes when averaged over the first 24 h of photosynthesis. However, within the initial 3 h of photosynthesis, the rate followed an opposite trend: The bacteria with the lowest H(2)ase activity photosynthesized acetic acid the fastest. These results suggest a two-pathway mechanism: a high quantum efficiency charge-transfer pathway to H(2)ase generating H-2 as a molecular intermediate that dominates at long time scales (24 h), and a direct energy-transducing enzymatic pathway responsible for acetic acid production at short time scales (3 h). This work represents a promising platform to utilize conventional spectroscopic methodology to extract insights from more complex biotic-abiotic hybrid systems.
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