Quantification of Pore Connectivity in Hierarchically Porous Carbon by Percolation Effect Integrated Differential Hysteresis Scanning

Abstract

A thorough understanding of pore architecture is essential for grasping its effects on mass transfer processes in various applications, a challenge that has long persisted. Conventional gas sorption methods cannot provide direct insights into pore geometry, connectivity, and other detailed structural characteristics. Here, we present a robust percolation effect integrated differential hysteresis scanning (PE-DHS) method that quantitatively evaluates the size and quantity of different pore geometries in various porous materials through hysteresis loop scanning. Alongside a detailed measurement program and experimental procedures, we performed an in-depth analysis of the phase transition behaviors during the filling and emptying process in pores of diverse shapes, offering a systematic explanation of the guiding mechanisms and the derivation of relevant formulas for PE-DHS. Additionally, we selected two samples with distinct d_pore and d_win characteristics to validate our analysis. A series of wood-based carbon materials with varying delignified pretreatment were chosen to test the analytical capabilities of PE-DHS on more complex and disordered pore networks with wider pore size distribution. Based on PE-DHS analysis, we introduced an index called the mean diameter/window ratio (MDWR) to quantify the degree of constriction in each cavity, thereby transforming conventional pore size distribution into a two-dimensional representation. Moving forward, the PE-DHS method is anticipated to become accessible to all and applicable to various materials with complex pore structures.