Work function based sensing of alkanes and alcohols with benzene tricarboxylate linked metal organic frameworks

Metalorganic frameworks (MOFs) are porous crystalline materials that can be synthesized using various metal ions and organic linkers. Due to their great physical, chemical, and geometrical variety, MOFs are very attractive for the potential application as selective gas sensing materials. The selectivity and sensitivity towards target gases is affected by chemical and/or geometrical properties of sensing layers. In this study we examine work function based gas sensing properties of MOFs, consisting of the same organic linker, benzene tricarboxylate (BTC), and different metal sites (Co, Ni, Cd, Al), towards different linear alkanes and monohydric alcohols at room temperature. The influence of oxygen and humidity on the gas sensing performances as well as the possible reaction mechanism are discussed. It was shown that exposure to alcohol leads to strong and concentration dependent changes in work function that increase with increasing length of the carbon chain of the alcohol while alkanes with similar carbon chains can hardly be detected. Moreover, the type of the metal site does not affect sensing of alcohols and alkanes qualitatively. By analysing the influence of size and polarity of the target gases, we assume that adsorption mechanisms and adsorption sites on BTC-MOF for polar and nonpolar molecules are different. (C) 2013 Elsevier B.V. All rights reserved.