Robust Carrier Migration through Carbon Dots Embedded in a C,S,N-TiO₂/Bi₁₂O₁₇Cl₂ Nanocomposite for Photocatalytic N₂ Reduction to NH₃

To avoid environmental issues and an energy shortage, environmentally friendly and energy-saving photocatalytic ammonia synthesis has received immense attention. Herein, novel C,S,N-doped TiO₂/Bi₁₂O₁₇Cl₂/C-Dots (C,S,N-TiO₂/BC/CD) nanocomposites were constructed through inexpensive precursors and a simple strategy, in which carbon dot (CD) particles were scattered uniformly on the surface of C,S,N-TiO₂/BC nanocomposites. The tri-element codoping, BC combination, and embedding of CD effectively promoted light harvesting ability, suppressed the carrier recombination, and boosted nitrogen activation. The synthesized nanocomposite enabled an ammonia generation rate up to 27134 μmol L^-1 g^-1 without the aid of any sacrificial agents, which surpassed 6.57 times that of pristine TiO₂. Moreover, the catalyst exhibited supreme stability with almost constant generation efficiencies for at least four runs. This prominent efficiency can be assigned to the step-scheme heterojunction configuration, which remarkably expanded the lifetime of photoinduced charges and improved the spatial segregation of electrons and holes. The synergistic interplay between C,S,N-TiO₂, BC, and CD in the heterojunction structure enhanced electron transportation, thereby promoting the photocatalytic nitrogen fixation reaction. Our research represents a beneficial strategy for designing robust TiO₂-based catalysts for photocatalytic ammonia synthesis.