Fabrication and photocatalytic performance of highly active exposed facets ZnO hexagonal cap/Ti3C2 MXene composites

Herein, a novel zinc oxide (ZnO) hexagonal cap with exposed polar facets/MXene composite was synthesized via a simple hydrothermal method. The analysis of the morphology and structure of these composites as well as the results of photochemical property measurements showed that a heterojunction was formed between ZnO and MXene. After testing the photocatalytic degradation of methyl orange, the ZnO hexagonal cap with 3 mL MXene showed the highest photodegradation efficiency of 87.8 % within 60 min under a xenon lamp. Active species capture experiments showed that •OH and h+ species were the main contributors to the degradation of methyl orange (MO). We proposed a possible mechanism for the excellent photocatalytic activity of ZnO hexagonal cap@Ti3C2 MXene. The Schottky barrier hindering the photogenerated electron recombination, the hexagonal cap morphology with highly active exposed facets, and the hollow structure favoring the adsorption of contaminants were all beneficial to achieve a high catalytic activity. This work provides new insight into the design of metal oxide/MXene photocatalysts.