The “falling cards model” for the structure of microporous carbons

Microporous and activated carbons have numerous applications ranging from gas absorbers to liquid decolorizers and are often called carbon molecular sieves. Their properties depend critically on the size of their pores and pore openings. Their structures are very complex and have defied a description which can explain the structural changes which occur during the thermal or chemical treatments necessary to adjust their properties. Here, we present a simple qualitative model, the “falling cards model”, which describes how the pore size and structure of these important materials changes with processing conditions. Comparison to experiment shows that the model works well. This conceptual picture has guided our attempts to design and synthesize carbons for the latest generation of advanced batteries and we believe it will be important in other attempts to make designer carbons for advanced materials applications.