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

Abstract

Highly efficient light-harvesting systems (LHSs) with the sequential energy transfer process are important for utilizing solar energy in photosynthesis. However, most light-harvesting systems are nanoparticles and vesicles, which are difficult to prepare and recycle. In this paper, we developed a light-harvesting system based on amino-methyl coumarin 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−BY 40−PhB system could reach 98.77% in ethanol, which was much higher than that with the main active catalyst PhB alone. In order to recycle and reuse the above catalysts, a facile, simple, and highly efficient light-harvesting cotton photocatalyst AMCA/BY 40/β-SCD-PhB-MCFs was prepared via three steps of cationization of cotton fibers (MCFs), sulfobutylether-β-cyclodextrin (β-SCD) inclusion of donor fluorophores, and final immobilization of fluorophores. These light-harvesting cotton fibers showed excellent catalytic performance, and the catalysis rate of the CDC reaction was 1.57 times higher than that of the PhB-MCFs alone. Its special "ring dyeing" and hierarchical pore structure 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 cotton fiber synergistically enhanced the energy transfer process. Furthermore, the light-harvesting cotton fibers showed high reusability, which could be easily recovered and reused five times without significant catalyst leaching. More interestingly, the fiber could be easily loaded in microchannels of the continuous flow reactor to catalyze the CDC reaction, which successfully achieved gram-scale photosynthesis due to the large specific surface area and easy mass transfer of fiber catalysts.