Rapid Synthesis of Zeolitic Imidazole Frameworks in Laser-Induced Graphene Microreactors

Various approaches to synthesize zeolitic imidazole frameworks (ZIFs) have been developed, such as solvothermal, sonochemical, microfluidic, and mechanochemical reactions. However, most of them are time consuming and involve complex processing steps, thus they cannot rapidly screen potential candidates to obtain ZIFs on demand. Such a challenge calls for efficient synthetic approaches. Herein, this challenge is overcome by employing two nonconventional heating strategies, that is, microwave and Joule heating, which are induced by laser-induced graphene (LIG) microreactors, to rapidly synthesize ZIFs. In the first reaction, the LIG acts as a susceptor that absorbs electromagnetic energy, which is converted into heat. In the latter one, LIG acts an electrical conductor that converts electrical energy to heat. Both of them can rapidly heat up the reactor, accelerating the crystal growth for synthesizing ZIFs with well-controlled morphology and crystallinity. To demonstrate a conceptual application, a ZIF-67/LIG composite was converted into Co/CoNC/LIG by a CO₂ laser-induced process. It showed excellent performance in the oxygen reduction reaction with a half-wave potential (E_1/2 ) of 0.798 V, and superior methanol tolerance and long-term stability. These rapid and facile synthesis methodologies will enable quick optimization of reaction conditions and fast screening of compound libraries for searching new materials, paving the way to high-throughput and autonomous nanomanufacturing.