Enhanced TiO2 Photocatalysts with Open Porous Framework Structure for Improved Continuous Photocatalysis and Solar Fuel Production

Titanium dioxide (TiO₂) has emerged as a leading photocatalyst for solar energy conversion and environmental applications due to its high stability, non-toxicity, and suitability for carbon dioxide (CO₂) reduction [1]. This study presents synthesis and characterization of a novel TiO₂ photocatalyst with enhanced mass transport properties to improve photocatalytic performance in continuous reactors. TiO₂-Aerogels, with their high surface area and porosity, show potential for enhancing photocatalytic applications, especially in flow-through photoreactors. However, the small pore size (< 1 µm) of TiO₂-Aerogels limits their effectiveness due to purely diffusive mass transport [2]. To overcome this limitation, a highly open porous and interconnected TiO₂ photocatalyst was synthesized through liquid phase deposition (LPD) adopted from Mbulanga et al. [3] on a sacrificial tetrapodal zinc oxide (t-ZnO) backbone. The resulting framework aeromaterial (FAM) features pores with diameters between 1 µm and 100 µm, a density of 0.03 g/cm³ (99.3% porosity), and a gravimetric surface area of approximately 40,000 cm²/g. Unlike common TiO₂-aerogels, this synthesis route produces an interconnected open-porous structure capable of withstanding gas flow velocities up to 0.16 m/s.
Characterization of the synthesized TiO₂ photocatalysts was conducted using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The findings reveal a highly porous structure predominantly in the anatase phase post heat treatment at 500°C for 4 hours. Photocatalytic performance was evaluated by the degradation of methylene blue under UV light irradiation (365 nm), with the highly porous TiO₂ demonstrating superior weight-specific activity compared to Degussa P25-TiO₂. Additionally, a flow-through reactor was designed for the continuous decomposition of methylene blue, showcasing the practical capabilities of FAM-TiO₂ in real-world applications. These results highlight the potential of the synthesized TiO₂ photocatalyst for enhanced photocatalytic performance in environmental and energy applications, particularly in solar fuel production such as hydrogen and e-fuels.
[1] Zhang, T. et al. Chinese Journal of Catalysis, 43, 2022, 2500–2529
[2] Matter, F. et al. Chem. Mater., 35, 2023, 7995–8008
[3] Mbulanga, C.M. et al. Appl. Phys. A, 126, 2020, 1–14