Water in Pores: The Gibbs-Thomson Effect

When we have a material in two phases and a surface between them, the material tries to minimize the interface area in order to reduce the excess of associated surface energy. The thermodynamic system reacts minimizing the Gibbs free energy. According to the Gibbs' surface thermodynamics, the Gibbs–Thomson effect arises. This phenomenon is relevant to the shift, with respect to the bulk system, of the melting and freezing temperatures of a confined substance, and it is observed in porous frameworks as a function of pore size. Here, we will consider the literature regarding the Gibbs-Thomson effect as observed for the confinement of water in mesoporous silica, porous carbon materials and biochar. Besides the investigation of temperature shift, we will evidence the researchers' specific interest to the liquid-like interfacial layer which is present between the walls of the pores and the confined phase.