How boron is adsorbed by oxygen-containing groups functionalized graphene: A density functional theory study

We employed density functional theory to investigate the adsorption mechanism of B(OH)3 and B(OH)4- on different graphene models: graphene with 20 carbon rings (G20), hydroxyl-modified graphene (G20-OH), and carboxyl-modified graphene (G20-COOH). The enthalpy of adsorption for B(OH)3 and B(OH)4- was as follows: G20 (-9.24 and-3.51 eV), G20-OH (-9.38 and-3.89 eV), and G20-COOH (-10.28 and-4.83 eV). The free energy of adsorption values were: G20 (-8.82 and-3.16 eV), G20-OH (-8.85 and-3.45 eV), G20-COOH (-9.66 and-4.27 eV). B(OH)3 exhibited easier adsorption than B(OH)4- within these groups. The interaction forces between B(OH)3/B(OH)4- and oxygen-containing groups were quantified, highlighting their role in determining the differential adsorption of B(OH)3 and B(OH)4-. Hydrogen bonding, van der Waals interaction, and steric effects were the main contributing factors to the adsorption process. G20 displayed stronger van der Waals forces with B(OH)3 than with B(OH)4- , while G20-COOH exhibited significantly stronger van der Waals forces with B(OH)3. The decreased steric hindrance contributed to the increased adsorption of G20-COOH with B (OH)3. Hydrogen bonding and reduced van der Waals forces played a role in the higher adsorption of G20-COOH with B(OH)4-. These findings inform strategies for efficiently removing boron species by understanding their adsorption mechanism on graphene.

Automated summary

Density functional theory was employed to investigate the adsorption mechanism of B(OH)3 and B(OH)4- on different graphene models. The interaction forces between B(OH)3/B(OH)4- and oxygen-containing groups were quantified, highlighting their role in determining the differential adsorption. Hydrogen bonding, van der Waals interaction, and steric effects were found to be the main contributing factors to the adsorption process.