Construction of a metal-free photocatalyst via encapsulation of 1,2,3,5-tetrakis(carbazole-9-yl)-4,6-dicyanobenzene in a carboxymethylcellulose-based hydrogel for photocatalytic lactic acid production

The efficient application of solar energy to realize photocatalytic biomass conversion to value-added chemicals is of significance. Herein, we propose a novel metal-free photocatalyst (4CzIPN@CMC-HG), which was prepared by encapsulating 1,2,3,5-tetrakis(carbazole-9-yl)-4,6-dicyanobenzene (4CzIPN) in a carboxymethylcellulose-based hydrogel (CMC-HG) using a one-step thermal polymerization strategy. 4CzIPN@CMC-HG has an efficient photon-to-electron conversion rate, excellent visible light absorption, fast photogenerated carrier migration/separation, and high photocatalytic activity, with 90.7% yield of lactic acid (LA) and 100.0% conversion of xylose due to the synergistic effects between 4CzIPN and CMC-HG. 4CzIPN@CMC-HG showed remarkable universality and excellent stability, and the 1000-times amplification system indicated that this system has a potential industrial application in LA production. Furthermore, trapping experiments indicated that OH, h(+), O-1(2), and O-2(-) contributed to LA synthesis, with O-2(-) taking a leading role. These results showed the promising application prospects of metal-free photocatalysts in the photocatalytic biomass conversion to value-added chemicals.

Automated summary

In this study, a novel metal-free photocatalyst (4CzIPN@CMC-HG) was proposed, which achieved efficient photocatalytic biomass conversion to value-added chemicals. 4CzIPN@CMC-HG exhibited excellent photon-to-electron conversion rate, visible light absorption, and photocatalytic activity for lactic acid production. The system also showed universality, stability, and potential industrial application. The trapping experiments revealed the contributions of different reactive species in lactic acid synthesis, with O-2(-) playing a leading role.