Photocatalytic performance of K2Ti6O13 whiskers to H2 evolution and CO2 photo-reduction

Abstract K 2 Ti 6 O 13 whiskers were synthesized by conventional sol-gel method, sono-chemical assisted and microwave assisted sol-gel method in order to obtain catalysts with different particle sizes and to modify their optical, textural and electrochemical properties. These modifications improved their photocatalytic activity for H 2 evolution and CO 2 photo-reduction. Long K 2 Ti 6 O 13 whiskers prepared by ultrasound assisted sol-gel method are the most active photocatalysts for the hydrogen evolution reaction using pure water as reactant (U-SG, 10,065 µmol g −1 ). In contrast, an opposite behavior was observed using a mixture of ethanol-water, where the highest activity was achieved by the shortest and less crystalline K 2 Ti 6 O 13 whiskers (C-SG, 3,2871 µmol g −1 ). In case of CO 2 photo-reduction, long whiskers that were also prepared by the sono-chemical assisted sol-gel method were the most active to transform CO 2 to formaldehyde, methane, methanol and hydrogen. The E FB value of this catalyst is located very close to the potential for formaldehyde production and favors the selectivity to this organic product.