Exciton dissociation and transfer behavior and surface reaction mechanism in Donor–Acceptor organic semiconductor photocatalytic separation of uranium

Photocatalytic uranium extraction from nuclear effluent is a promising approach for avoiding environmental damage and recovering uranium resources. Here, a hollow tube-like D-A organic semiconductor photocatalyst consisting of triazine (Acceptor) and carbon ring (Donnor) was synthesized via two cheap monomers, sodium alginate and melamine. The incorporation of carbon ring structure could endow g-C3N4 with unique hollow hexagonal tube-like morphology, modulate the electronic excitation model, lower the energy for exciton dissociation, and promote the adsorption and activation of O2. Thus, the D-A photocatalyst established high efficiency of photocatalytic uranium separation under LED light and high concentration of anions and cations interference. More importantly, we propose a novel theory, that photocatalytic-induced-uranyl-coordination-reaction (PIUCR), and highlight that the formation rate and pathway of crystal nucleus is the most crucial step for the surface reaction of photocatalytic uranium separation. This study provides insights and guidelines for the in-depth understanding of the photocatalytic separation of uranium. [Display omitted] •HCNCR exhibits efficient photocatalytic uranium separation under LED light and high anion/cation interference.•HCNCR shows charge-transfer excitation with long carrier lifetime (44.76 ns) and low exciton dissociation energy (112 meV).•A novel theory, photocatalytic-induced-uranyl-coordination-reaction (PIUCR), has been proposed to guide future researches.