Here, we show for the first time that the photocatalytic activity of covalent triazine-based frameworks (CTFs) can be efficiently improved using a facile sulfur-doping approach. The sulfur-doped CTFs show superior photocatalytic activity and stability in hydrogen evolution from water under visible light irradiation over pristine CTFs and g-C₃N₄. The significantly improved catalytic efficiency was attributed to sulfur-doping in the frameworks, which results in enhanced adsorption of visible light, reduced recombination of free charge carriers, and rapid separation and transportation of photogenerated electron–holes.

An ultra-low concentration of Au in aqueous solution is selectively detected and recovered by using a covalent organic framework bearing thioether pendant arms.