Before testing, the samples were coated with Au over a period of 1 minute using a Balzers PV205P coater.In order to characterise the adsorption properties, nitrogen adsorption/desorption isotherms at 77 K and parameters such as surface area (), total volume (), and mean size () of pores were determined using an ASAP 2020 instrument (Accelerated Surface Area and Porosimetry???Micromeritics Instrume