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Formaldehyde is an essential building block for hundreds of chemicals and a promising liquid organic hydrogen carrier (LOHC), yet its indirect energy-intensive synthesis process prohibits it from playing a more significant role. Here we report a direct CO reduction to formaldehyde (CORTF) process that utilizes hydrogen underpotential deposition to overcome the thermodynamic barrier and the scaling relationship restriction. This is the first time that this reaction has been realized under ambient conditions. Using molybdenum phosphide as a catalyst, formaldehyde was produced with nearly a 100% faradaic efficiency in aqueous KOH solution, with its formation rate being one order of magnitude higher compared with the state-of-the-art thermal catalysis approach. Simultaneous tuning of the current density and reaction temperature led to a more selective and productive formaldehyde synthesis, indicating the electrochemical and thermal duality of this reaction. DFT calculations revealed that the desorption of the *H 2 CO intermediate likely served as the rate-limiting step, and the participation of H 2 O made the reaction thermodynamically favorable. Furthermore, a full-cell reaction set-up was demonstrated with CO hydrogenation to HCHO achieved without any energy input, which fully realized the spontaneous potential of the reaction. Our study shows the feasibility of combining thermal and electrochemical approaches for realizing the thermodynamics and for scaling relationship-confined reactions, which could serve as a new strategy in future reaction design.
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The Effects of Pulse Frequency on Chemical Species Formation in a Nanosecond Pulsed Plasma Gas-liquid Film Reactor
The influence of pulse frequency (1−60 kHz) in a nanosecond filamentary discharge propagating along a flowing liquid water film was assessed with regards to the formation of chemical species with argon and helium carrier gasses. The production rate and energy yield for H₂O₂ and H₂ were measured for both carrier gases, and O₂ formation was determined for helium. The effect of pulse frequency on the energy dissipated per pulse as well as electron density was also investigated. The results indicate that the energy yield for H₂O₂ decreases with increasing pulse frequency while the energy yields of H₂ and O₂ remain relatively unaffected. It is proposed that the difference in the trends of the liquid versus the significantly longer residence time of the liquid phase allowing for more degradation of formed hydrogen peroxide before it is able exit the reactor.
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- Award ID(s):
- 1702166
- PAR ID:
- 10221338
- Date Published:
- Journal Name:
- International journal of plasma environmental science technology
- Volume:
- 14
- Issue:
- 1
- ISSN:
- 2435-0125
- Page Range / eLocation ID:
- e01008
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.34343/ijpest.2020.14.e01008
