In-situ embedded ultrafine Bi12O17Br2 nanotubes in MOF-derived hierarchical porous carbon for enhanced photocatalytic CO2 conversion to CO.

• The Bi 12 O 17 Br 2 nanotubes with average diameter of 5 nm were embedded inside the ZIF-67-derived hollow porous carbon materials. • The abundant confined spaces of porous carbon ensured more CO 2 molecules participate in the photoreduction reaction. • The tight interfacial contact between the Bi 12 O 17 Br 2 and porous carbon boosted the charge separation and transfer. • The composites displayed 2.95 times higher CO yield than that of the pure Bi 12 O 17 Br 2. Increasing the utilization efficiency of photogenerated electrons is highly recognized as one of the efficient approaches to boost the photocatalytic CO 2 conversion efficiency. Herein, ZIF-67-derived porous carbon (PC) material was employed for the construction of PC@ultrafine Bi 12 O 17 Br 2 nanotubes (PC@BOB NTs) composites through a facile solvothermal synthesis in order to optimize the use of excited electrons in the BOB NTs. Photoelectrochemical characterization results revealed that the introduction of PC material achieved a faster charge separation rate in the PC@BOB composites, ensuring more photogenerated electrons participate in the CO 2 adsorption and activation process. Moreover, the pore structures of ZIF-67-derived PC material provided abundant confined spaces for the enrichment of CO 2 molecules. After 5 h of Xenon lamp irradiation, PC@BOB composites exhibited obviously increased photocatalytic CO 2 reduction activity in the pure water. When the addition amount of PC was 5 wt%, the PC@BOB-2 composite showed the highest CO evolution rate of 359.70 µmol/g, which was 2.95 times higher than that of the pure BOB NTs. This work provides some independent insights into the applications of Metal-Organic Framework (MOF)-derived hierarchical porous structures to strengthen the CO 2 enrichment, as well as the excited charge utilization efficiency, thus achieving a high solar-to-fuel conversion efficiency. [ABSTRACT FROM AUTHOR]