Simultaneous Enhancement of Electrical Conductivity and Porosity of a Metal–Organic Framework Toward Thermoelectric Applications

Abstract

Metal–organic frameworks (MOFs) exhibit large surface areas and low thermal conductivity, making them promising for thermoelectric generation. However, their limited electrical conductivity poses a significant hurdle to be practically useful. Traditionally, enhancing the electrical conductivity of MOFs typically comes at the cost of reducing surface area, thereby increasing thermal conductivity. This study introduces an approach to simultaneously boost the electrical conductivity and porosity of a MOF-based material while maintaining remarkably low thermal conductivity. The electrically conductive poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is deployed to nucleate the growth of Cu3(BTC)2 (or simply CuBTC, where BTC = benzene-1,3,5-tricarboxylic acid), resulting in the synthesis of composites labeled CPP-y (where y denotes wt% PEDOT:PSS). Predictably, the CPP-y composites are more electrically conductive than pure CuBTC, achieving an electrical conductivity exceeding 1.40 S cm−1 at room temperature. Furthermore, the CPP-y composites exhibit consistently high Brunauer–Emmett–Teller (BET) surface areas of ≈1600 m2 g−1, comparable to pristine CuBTC, while maintaining thermal conductivities below 0.04 W m−1 K−1 at room temperature. With a high Seebeck coefficient in the range 180–373 µV K−1, CPP-15 and CPP-23 demonstrate a figure-of-merit (zT) of 0.25 and 0.11, respectively, at 285 K, marking a substantial achievement for MOF-based materials.