Researchers at the Lawrence Berkeley National Laboratory (Berkeley Lab) and their colleagues studied the chemical mechanisms that allow photocatalysis to remove pollution from indoor air and urban atmospheres, as well as allow self-cleaning surfaces to work. The basis of the process is a catalyst such as titanium dioxide (TiO2) energized by light. Building materials and coatings with nano-sized TiO2 particles are gaining market share. Photocatalytic products include self-cleaning building envelope materials (coatings, mortar, plaster, architectural fabrics and tiles) and indoor air purifiers.
At the American Geophysical Union Meeting in San Francisco this week, the research team reported on their study of de-noxification (nitrogen oxide (NOx) removal) and de-soiling (removal of deposited black carbon or soot) through photocatalysis. Their work revealed that water vapor, carbon and salt impurities can affect the rate and mechanisms of de-noxification. Photocatalysis was also shown to be effective for complete oxidation of soot into CO2, under realistic weathering conditions. These results need to be taken into account in the design of photocatalytic technologies to maximize the effectiveness of NOx and soot removal.
The research was conducted by Berkeley Lab's Mohamad Sleiman, Olivier Rosseler, Thomas Kirchstetter, Hendrik Bluhm, Musahid Ahmed, Miquel Salmeron, and Hugo Destaillats; Nahuel Montesinos, Damian Bikiel of the University of Buenos Aires; and Marta Litter of Argentina's Comisión Nacional de Energía Atómica.