“…An isotherm is the main data source for surface area estimation. Some researchers have suggested that the pressure range of BET analysis should obey four criteria; some researchers have modified the traditional BET equation to obtain a more reasonable surface area; − and some others have developed new isotherm models to describe the adsorption process and then derive the surface area, e.g., zeta adsorption isotherms, , cluster sorption isotherms, − and the isotherm model based on Polanyi’s theory. , In addition to utilizing isotherms, some other methods can also determine the surface area, such as using electron microscopy , and mathematically calculating according to the crystal structure. , Most of these studies have concluded that the traditional BET method will overestimate the surface area. ,,,, …”