Researchers from the University of Antwerp and KU Leuven (University of Leuven), Belgium, have developed an all-gas-phase solid and stand-alone photo-electrochemical (PEC) cell that produces hydrogen gas from volatile organic contaminated air and light. The device recovers part of the energy stored in airborne organic pollutants by the production of hydrogen, while mineralizing the contaminants to less harmful CO2.
The PEC degrades organic contaminants and snd produces the hydrogen gas—without applying any external bias—in separate electrode compartments. Oxidation of volatile organic compounds (VOC) occurs at the photo-anode, while hydrogen is produced at the (dark) cathode on the opposite side of a proton-conducting solid electrolyte membrane. A paper on the work is published in the journal ChemSusChem.
We use a small device with two rooms separated by a membrane. Air is purified on one side, while on the other side hydrogen gas is produced from a part of the degradation products. This hydrogen gas can be stored and used later as fuel, as is already being done in some hydrogen buses, for example.—Professor Sammy Verbruggen (UAntwerp/KU Leuven), lead author
The system works most efficiently with organic pollutants in inert carrier gas. In the presence of oxygen, the cell performs less efficiently but still significant photocurrents are generated, showing the cell can be run on organic contaminated air.
|Schematic representation of the photo-electrochemical cell. Verbruggen et al. Click to enlarge.|
The results highlighted a tradeoff when using PEC cells for organic waste gas treatment: the presence of oxygen promotes more complete mineralization to CO2, but limits the generated photocurrent and hydrogen evolution.
We are currently working on a scale of only a few square centimetres. At a later stage, we would like to scale up our technology to make the process industrially applicable. We are also working on improving our materials so we can use sunlight more efficiently to trigger the reactions.—Sammy Verbruggen
S. W. Verbruggen, M. Van Hal, T. Bosserez, J. Rongé, B. Hauchecorne, J. A. Martens, S. Lenaerts (2017) “Harvesting Hydrogen Gas from Air Pollutants with an Unbiased Gas Phase Photoelectrochemical Cell” ChemSusChem doi: 10.1002/cssc.201601806