An integration system derived from LDHs for CO2 direct capture and photocatalytic coupling reaction

Aiming at integration of CO2 capture and utilization, we put forward a nanocatalyst for coupling photocatalytic CO2 reduction with 5-hydroxymethylfurfural (5-HMF) oxidation. Specifically, we synthesize a carbonate-type CuCoAl-layered double hydroxide (LDH) to pre-enrich the raw material of the half reduction reaction. In the inert atmosphere, CO32− located in the interlayers realized in situ reduction catalyzed by the metal cations on the layers, and this was coupled with 5-HMF oxidation catalyzed by the hydroxyl sites, thus generating CO as a reduction product and 2.5-furandiformaldehyde (DFF), 5-formyl-2-furanacarboxylic acid (FFCA), and 2.5-furan dicarboxylic acid (FDCA) as oxidation products. A series of in situ Fourier transform infrared (FTIR) spectroscopy with assistance of 13C labeling characterizations clarified the above in situ transformation process and further revealed the important role of tuning the electronic structure by selectively etching the LDHs layers in promoting catalytic performance. More importantly, the consumed CO32− could be easily supplied by CO2 in air, which would endowed the nanocatalyst with good recycle performance.