Oxidation-locking of hydrogen-substituted γ-graphdiyne via a two-step hydrothermal route: from enhanced catalyst to bifunctional quantum dots

As a rising new member of carbon allotropes, graphdiyne has shown great potential in various fields due to its fascinating properties. Herein, a controlled two-step hydrothermal route was employed to convert hydrogen-substituted γ-graphdiyne into two functional derivatives: graphdiyne oxides (OGDY) and graphdiyne oxide quantum dots (OGDYQD). Systematic characterization revealed distinct differences in morphology, chemical structure, and optical properties between precursors and derivatives. Especially, the existence of alkyne bonds was demonstrated through evidence from Fourier transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL), and selective oxidation experiments, which provides new insights for the characterization of graphdiyne materials. Moreover, we identified an oxidation-locking phenomenon governing selective alkyne oxidation at specific sites during synthesis. The oxidation-locking feature endowed significant application potential upon both derivatives: OGDY exhibited excellent photocatalytic ability in the degradation of cationic dyes, achieving efficiency ∼5–200 higher than those of other carbon-based materials; while OGDYQD could achieve ultrasensitive electrochemical detection of methyl orange with a limit of detection (LOD) as low as 0.032 μM, as well as serve as an excellent catalyst, which was comparable to metal catalysts, for the hydrogenation of 4-nitrophenol. This work provides fundamental insights into sp-carbon reactivity while delivering practical platforms for multiple applications.