Developing realistic molecular models of biochars

Biochars are widely studied porous materials with applications as economical alternatives to traditional adsorbents, but a molecular-level understanding of their structures is hampered by a lack of good computational models. In the first part one of this two-part study, we reviewed experimental methods used to characterize biochars and compiled a database of publicly available experimental data. Here, we present an iterative approach that allows building biochar molecular models, based upon their experimentally derived chemical descriptors (e.g., H/C and O/C ratios, functional groups, aromaticity index) and validated upon emerging physicochemical properties (e.g., true density and high-resolution transmission electron microscopy [HRTEM]). This approach allows us to build the first, to our knowledge, molecular models of biochar materials, representative of woody biochars produced across a broad range of pyrolysis temperatures: 400°C, 600°C, and high 800°C. To ensure the accessibility of these models for use by the broad research community, we share these models, assigned with the OPLS-AA force field and setup for simulations with GROMACS. •Construction of realistic biochar models for molecular dynamics simulations with GROMACS•Produced models match chemical and physical experimental descriptors for woody biochars•Descriptors derived by fitting a 300+ sample collection of experimental biochar data•The dataset and molecular building blocks used in the iterative protocol are shared In the second part of this two-part study, Wood et al. report an iterative approach for the construction of molecular models of biochar materials, guided by experimental data. The obtained models can be readily used in studies using molecular dynamics simulations, and the underlying dataset is provided for the community.