Title : Room temperature reduction of carbon dioxide using localized surface plasmon energy
Abstract:
World’s increasing energy demand can be easily met by the fossil fuel reserves for next several decades without an impact on environments if the carbon dioxide (CO2) emission can be reduced or mitigated. Photocatalytic conversion of CO2 to useful chemicals is an attractive option but not practical yet due to low conversion rate and high cost of precious metal catalyst used. Here, we show that localized surface plasmon (LSP) resonance energies of aluminum (Al) plasmonic nanoparticles, excited by high energy electrons, can be used to reduce CO2 by carbon at room temperature according to the reverse Boudouard reaction: CO2+C → 2CO. Al nanoparticles, with diameters ranging from 30 nm to 300 nm, were loaded on either amorphous carbon film or polycrystalline graphite support and introduced in an environmental transmission electron microscope (ETEM), equipped with a monochromated electron source (80 meV energy resolution) and operated at 80 kV, to excite Al LSP resonance modes, and characterize the CO2 reduction rate based on the measured carbon etching rate. In CO2 environment of ≈ 50 Pa, the carbon etching was observed near Al nanoparticles at a rate that is ≈ 10 times faster than in the regions away from the particles when irradiated by the same electron beam flux. Electron energy-loss spectroscopy was used to measure the thickness reduction of graphite around the Al particles to obtain the net carbon etching rate due to the energy provided by LSP resonance. Carbon etching rates were also obtained as function of the number of Al nanoparticles, CO2 pressure, and LSP resonance amplitude. A complete analysis of mechanism and scalability details will be presented. Potentially the reduction can be achieved using sunlight to excite LSP resonances on Al particles and that will make this cost-effective process scalable at industrial level requiring only sunlight and earth-abundant Al and C for CO2 reduction.
