Boosting thermoelectric performance by in situ growth of metal organic framework on carbon nanotube and subsequent annealing

Despite the significant progress in thermoelectric composites in the last five years, examining the existing main body of publications shows the scarcity of composite systems and limited preparation strategies. Metal-organic frameworks (MOFs) have been extensively studied and have wide applications, however, MOF-related thermoelectric composites have been seldom reported mainly due to their poor electrical conductivity. In this work, we propose a conceptual strategy, in situ growing reaction and subsequent annealing, to achieve zeolitic imidazolate framework 67/carbon nanotube (ZIF-67@CNT) composites with a unique microstructure of MOFs growing on CNT surfaces. The ZIF-67@CNT composites display outstanding and tunable thermoelectric properties. Annealing plays an important role in the composite morphology, structure and thermoelectric performance. Both the electrical conductivity (825.7 ± 12.0 S cm−1) and the figure of merit (ZT = ∼0.02) at room temperature are the highest in the experimental data reported so far for MOF-related materials, and even comparable to the corresponding theoretical values. The results inspire a new insight into MOF-related thermoelectric composites, which should be considered for future design strategies for novel high-performance thermoelectric composites.