Rational molecular design of P-doped porous carbon material for the VOCs adsorption

Abstract

The objective of this study was to identify and synthesize functional groups for the efficient adsorption of volatile organic compounds (VOCs) through a combination of theoretical calculations, molecular design, and experimental validation. The density functional theory (DFT) calculation, focusing on the P-containing functional groups, showed that methanol adsorption was dominated by the electrostatic interaction between the carbon surface and methanol, while toluene was mainly trapped through π-π dispersive interaction between toluene molecule and functional group structure. The experimental results showed the phosphorus-doped carbon materials (PCAC) prepared by directly activating potassium phytate had a phosphorus content of up to 4.5% (atom), mainly in the form of C—O—P(O)(OH)₂. The material exhibited a high specific area (987.6 m²·g⁻¹) and a large adsorption capacity for methanol (440.0 mg·g⁻¹) and toluene (350.1 mg·g⁻¹). These properties were superior to those of the specific commercial activated carbon (CAC) sample used for comparison in this study. The adsorption efficiencies per unit specific surface area of PCAC were 0.45 mg·g⁻¹ m⁻² for methanol and 0.35 mg·g⁻¹·m⁻² for toluene. This study provided a novel theoretical and experimental framework for the molecular design of polarized elements to enhance the adsorption of polar gases, offering significant advancements over existing commercial solutions.