Versatile nanocellulose-anatase TiO2 hybrid nanoparticles in Pickering emulsions for the photocatalytic degradation of organic and aqueous dyes

Hypothesis: Degradation of pollutants using photocatalysts is a surface strategy and their release is generally undesired in nature. Biobased particles with simultaneous activity in aqueous and organic phase could limit their amount for enhanced efficiency. Using photoactive materials as interfacial stabilizer for the preparation of Pickering emulsion should allow for its action on both phases. Experiments: We report the preparation of hybrid nanoparticles involving water-dispersible cellulose nanocrystals (CNC) and anatase TiO2. TiO2 nanoparticles were grown in situ on the CNC surface resulting in hybrids that could contain up to 40 wt % in TiO2 with a biobased core and interfacial properties. We measured their photocatalytic efficiency in water on a hydrophilic dye and in organic phase on a hydrophobic dye. Their photocatalytic activity was also observed on freeze-dried emulsions-templated aerogels. Results: The hybrids led to improved dispersability of TiO2 NPs in water and photocatalytic efficiency on watersoluble dye compared to ungrafted TiO2 NPs. When stabilizing the oil/water interface, they also simultaneously degrade an organic dye. Finally, the emulsion-based aerogels retained the hybrids photocatalytic activity. It results in novel, essentially biobased photocatalytic nanoparticles, highly versatile and able to degrade model dyes in aqueous suspensions, emulsions and aerogels.