# Porosity Local Analysis (PoLA): A New Approach to Describe the Porous Volume Distribution in Amorphous Carbons

## TL;DR

PoLA is a new method to analyze the porosity of amorphous carbons, enabling accurate prediction of gas adsorption behavior.

## Contribution

PoLA introduces a point-by-point analysis of porosity in amorphous materials, enabling unique characterization and prediction of adsorption behavior.

## Key findings

- PoLA partitions porous volume into micro-, meso-, and macropores based on distance from material walls.
- PoLA results strongly correlate with nitrogen adsorption isotherms at 77 K.
- Machine learning can predict adsorption isotherms using PoLA data.

## Abstract

A new procedure, named PoLA (Porous Local Analysis),
is presented
to describe the porosity of amorphous carbons accurately. Unlike models
based on predefined geometrical pores, PoLA is based on a point-by-point
description of the inner void, and it is particularly suitable for
amorphous materials. The porous volume is partitioned into small elements
(blocks) of user-defined size, and each block is assigned a micro-,
meso-, or macroporous nature according to its minimum distance from
the material walls. This method is very fast and characterizes any
porous volume uniquely: most importantly, this distribution of volume
allows one to predict the gas adsorption behavior of the material.
To show this, a number of carbon models have been defined, spanning
a large range of porosities, and the adsorption isotherm of nitrogen
at 77 K has been accurately simulated with Grand Canonical Monte Carlo
in each model. We show that PoLA porous volume distributions and adsorption
isotherms are strongly correlated so that N2 isotherms
at 77 K can be accurately predicted by a machine learning procedure
on the basis of PoLA results. We expect that this approach will be
of great help in the design of new adsorbents and in the interpretation
of experimental gas adsorption.