Self-assembly of a heterogeneous microreactor with carbon dots embedded in Ti-MOF derived ZnInS/TiO microcapsules for efficient CO photoreduction

The assembly of the heterogeneous microreactor is a promising approach for CO 2 photoreduction attributed to its abundant microchannel, intimate contact, high exposed surface area, and favorable heat-mass transfer. Herein, we developed a metal-organic framework (MOF) derived in situ transformation strategy to construct a carbon dot (CD)-decorated ZnIn 2 S 4 /TiO 2 (CDs/ZIS/TiO 2 ) microreactor. Taking advantages of this hierarchical structure, the CDs/ZnIn 2 S 4 /TiO 2 microreactor exhibits significantly enhanced photocatalytic CO 2 reduction activity with a CH 4 yield of 14.9 μmol g −1 h −1 and CH 4 selectivity of 75.6% in the absence of a sacrificial agent, where the electron consumption rate ( R electron ) of 157.6 μmol g −1 h −1 is 1.9 and 18.3 times higher than those of ZIS(60)/TiO 2 and bare ZnIn 2 S 4 , respectively. The combination of transient photo-induced voltage (TPV), in situ Fourier transform infrared and electron spin resonance (ESR) spectra illustrate the photocatalytic mechanism and the effect of CDs on the electron transfer behavior. This work emphasizes a facile technique for developing a CD-based microreactor to achieve high-efficiency photocatalytic CO 2 reduction performance. The assembly of the heterogeneous microreactor is a promising approach for CO 2 photoreduction attributed to its abundant microchannel, intimate contact, high exposed surface area, and favorable heat-mass transfer.