Charge-modulated CO2 capture of C3N nanosheet: Insights from DFT calculations

Increasing concerns about the atmospheric CO2 concentration and its impact on the environment promote developing new materials and technologies for efficient CO2 capture and conversion. Here, for the first time we investigate the CO2 adsorption on C3N nanosheet with different charge states by means of density functional theory calculations. It is found that injecting extra negative electrons instead of positive electrons can extremely improve CO2 adsorption capacity of C3N nanomaterial. The adsorption strength of CO2 molecules on this 3 e(-) negatively charged nanomaterial is 20 times of that on neutral surface while there is little difference between these on positively charged surface and the neutral surface. Interestingly, CO2 molecules can spontaneously adsorb and desorb from C3N sorbent with appropriate charge density range by injecting and removing extra negative charges. Importantly, this negatively charged C3N exhibits highly selective adsorption for CO2/C2H2, CO2/CH4, CO2/H-2, C2H2/CH4 and C2H2/H-2 mixtures through tuning charge density. Our theoretical results could provide guidance for designing high-capacity and high-selectivity CO2 capture materials.