Photocatalytic abatement of ambient NOx by TiO2 coated solar panels

Nitric oxide and nitrogen dioxide (combined, known as NOx) and their contribution to ozone and photochemical smog generation are persistent issues in urban environments. Many technologies have been developed to alleviate this issue, including photochemical transformation. While previous experiments have focused on incorporating photocatalysts into paving and building materials, we report coating glass substrates for the eventual application to solar panels that are inherently positioned to optimize the amount of solar exposure they receive, creating a surface compatible with photocatalytic coatings. As most photocatalyst materials absorb the ultraviolet spectrum outside the light range used for energy production, this approach could enable dual-functionalized solar panels for energy generation and air remediation. Proof of concept testing was conducted to determine the effectiveness of TiO2-based photocatalytic products to oxidize NOx to NO3-/HNO3. It was found that the tested TiO2-based photocatalytic products can successfully reduce NOx concentrations by up to 36%. With the success of laboratory proof of concept experiments, field testing was conducted to determine if glass panels coated with TiO2 products can reduce NOx concentrations in environmental conditions. Deionized water washes of the coated glass panels were analyzed through ion chromatography to determine the concentration of NO3- formed on the surface of the coated glass panels. Field testing resulted in flux values up to 33 mg of NO3- per m2 per day and an average flux up to 8.8 mg of NO3- per m2 per day, representing an order of magnitude value to evaluate possible large-scale implementation. Utilizing field testing results, scale-up estimations suggest widespread application would have a limited impact on total NOx concentrations. Still, at the local scale, deployment at sites with elevated NOx concentrations could meaningfully improve local air quality.