High-Performance Light-Harvesting Cotton Fiber Photocatalyst Inspired by "Ring Dyeing" for the Cross-Dehydrogenative Coupling Reaction

The light-harvesting cottonfiber AMCA/BY 40/beta-SCD-PhB-MCFswas employed for the photocatalytic CDC reaction. Highlyefficient light-harvesting systems (LHSs) with the sequentialenergy transfer process are important for utilizing solar energy inphotosynthesis. However, most light-harvesting systems are nanoparticlesand vesicles, which are difficult to prepare and recycle. In thispaper, we developed a light-harvesting system based on amino-methylcoumarin acid (AMCA), C.I. Basic Yellow 40 (BY 40), and phloxine B(PhB) organic dyes for photocatalytic cross-dehydrogenative coupling(CDC) reactions. The conversion of the CDC reaction using the AMCA-BY40-PhB system could reach 98.77% in ethanol, which was muchhigher than that with the main active catalyst PhB alone. In orderto recycle and reuse the above catalysts, a facile, simple, and highlyefficient light-harvesting cotton photocatalyst AMCA/BY 40/beta-SCD-PhB-MCFswas prepared via three steps of cationization of cotton fibers (MCFs),sulfobutylether-beta-cyclodextrin (beta-SCD) inclusion of donorfluorophores, and final immobilization of fluorophores. These light-harvestingcotton fibers showed excellent catalytic performance, and the catalysisrate of the CDC reaction was 1.57 times higher than that of the PhB-MCFsalone. Its special "ring dyeing" and hierarchical porestructure provided a favorable microenvironment for photocatalysis.The wide range in light absorption, highly efficient energy transfer(53.1%), and antenna efficiency (15.6) of the light-harvesting cottonfiber synergistically enhanced the energy transfer process. Furthermore,the light-harvesting cotton fibers showed high reusability, whichcould be easily recovered and reused five times without significantcatalyst leaching. More interestingly, the fiber could be easily loadedin microchannels of the continuous flow reactor to catalyze the CDCreaction, which successfully achieved gram-scale photosynthesis dueto the large specific surface area and easy mass transfer of fibercatalysts.