To a suspension of cellulose (300 mg) in a 50 mM aqueous sodium acetate solution (6 mL) at pH 5 (adjusted by the addition of HCl) at 37 °C was added cellulase (15 mg in 1.5 mL) in a 50 mM aqueous sodium acetate solution at pH 5. The suspension was incubated at 37 °C for 24 h, followed by 15 min at 90 °C and filtration through a syringe filter (0.2 µm). The filtered solution was stored at -4 °C. The pre-treated cellulose solution contained glucose (53±2 mM) and cellobiose (26±1 mM) as determined by HPLC. To a glass photoreactor vial (7.74 mL total volume) equipped with a magnetic stir bar was added 5 mg of TiO2 which was suspended in 2.95 mL of 2:1 v:v MeCN:pre-treated cellulose solution.