Laser-Induced Transformation of ZIF-8 into Highly Luminescent N-Doped Nanocarbons for Flexible Sensors

Abstract

Metal–organic frameworks (MOFs) like the zeolitic imidazolate framework (ZIF-8) have a high surface area, tunable porosity, and robust thermal and chemical stability, making them attractive candidates for various applications. Here, a strategy is shown that spans that functionality and provides strong photoluminescence (PL) emission, unlocking ZIF-8-based materials for chemical and temperature sensors based on PL. The approach is based on laser processing that dramatically boosts the PL response of laser-irradiated ZIF-8 (LI ZIF-8), achieving a 70-fold increase in intensity relative to the pristine material. The PL characteristics of the irradiated material can be easily tuned by varying the laser power and irradiation time with in situ and real-time spectroscopic analysis providing insights into the process dynamics. It is found that the observed PL enhancement is primarily due to the laser-induced transformation of ZIF-8 into nitrogen-doped nanocarbons and ZnO nanostructures. The versatility of this laser processing approach is leveraged to create flexible electronics by integrating the LI ZIF-8/nanocarbon architectures into thermoplastic polyurethane (TPU). The multifunctional composite material shows excellent performance as flexible electrodes for human-body monitoring applications, as well as both temperature and flexure sensors with remarkable mechanical resilience.