Synergistic effect of charge and strain engineering on porous g-C9N7 nanosheets for highly controllable CO2 capture and separation

Rational design of stable carbon nitride monolayer membranes for highly controllable CO2 capture and separation from CH4 and C2H2

CO2 capture and separation from natural and fuel gas are important industrial issues that refer to the control of CO2 emissions and the purification of target gases. Here, a novel non-planar g-C12N8 monolayer that could be synthesized via the supramolecular self-assembly strategy was identified using DFT calculations. The cohesive energy, phonon spectrum, BOMD, and mechanical stability criteria confirm the stability of the g-C12N8 monolayer. Our DFT calculations and MD simulations designate the g-C12N8 monolayer to perform as a superior CO2 separation membrane from CH4 and C2H2 gas owing to the high CO2 permeability and selectivity. Specifically, the CO2 permeability ranges from 1.21 × 107 to 1.53 × 107 GPU, while the selectivity of CO2/CH4 and CO2/C2H2 is 3.03 × 103 and 3.10 × 102 at 300 K, respectively, much higher than the Robeson upper bound and most of the reported 2D membranes, and even at high temperatures, the g-C12N8 monolayer-based CO2 separation membranes could operate with high performance. Further, at room temperature, the permeated CO2 gas can adsorb on the g-C12N8 surface with moderate adsorption energy and high capacity. These results indicate that the g-C12N8 membrane exhibits high performance for controlling CO2 capture and separation, which inevitably injects a new alternative of novel 2D membranes for CO2 separation and capture from CH4 and C2H2 in light of further experimental and theoretical research.

Synthesis and applications of biomass-derived porous carbon materials in energy utilization and environmental remediation

Renewable biomass and its waste are considered among the most promising applications materials owing to the depletion of fossil fuel and concerns about environmental pollution. Notably, advanced porous carbon materials derived from carbon-rich biomass precursors exhibit controllable pore structures, large surface areas, natural microstructures, and abundant functional groups. In addition, these three-dimensional structures provide sufficient reaction sites and fascinating physicochemical properties that are conducive to heteroatom doping and functional modification. This review systematically summarizes the design methods and related mechanisms of biomass-derived porous carbon materials (BDPCMs), discusses how the synthesis conditions influence the structure and performance of the carbon material, and emphasizes the importance of its use in energy utilization and environmental remediation applications. Current BDPCMs challenges and future development strategies are finally discussed to provide systematic information for further synthesis and performance optimization, which are expected to lead to novel ideas for the future development of bio-based carbon materials.

Superior Selective CO2 Adsorption and Separation over N2 and CH4 of Porous Carbon Nitride Nanosheets: Insights from GCMC and DFT Simulations

Development of high-performance materials for the capture and separation of CO₂ from the gas mixture is significant to alleviate carbon emission and mitigate the greenhouse effect. In this work, a novel structure of C₉N₇ slit was developed to explore its CO₂ adsorption capacity and selectivity using Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) calculations. Among varying slit widths, C₉N₇ with the slit width of 0.7 nm exhibited remarkable CO₂ uptake with superior CO₂/N₂ and CO₂/CH₄ selectivity. At 1 bar and 298 K, a maximum CO₂ adsorption capacity can be obtained as high as 7.06 mmol/g, and the selectivity of CO₂/N₂ and CO₂/CH₄ was 41.43 and 18.67, respectively. In the presence of H₂O, the CO₂ uptake of C₉N₇ slit decreased slightly as the water content increased, showing better water tolerance. Furthermore, the underlying mechanism of highly selective CO₂ adsorption and separation on the C₉N₇ surface was revealed. The closer the adsorption distance, the stronger the interaction energy between the gas molecule and the C₉N₇ surface. The strong interaction between the C₉N₇ nanosheet and the CO₂ molecule contributes to its impressive CO₂ uptake and selectivity performance, suggesting that the C₉N₇ slit could be a promising candidate for CO₂ capture and separation.