A DFT-based study of As₂O₃ adsorption using single and bimetallic atom-doped g-C₃N₄

Non-precious metal atom-doped g-C₃N₄ is a promising adsorbent for arsenic removal from coal-fired flue gas, but the adsorption process and mechanisms are unclear. This work systematically investigates As₂O₃ adsorption on single- and double-transition-metal-loaded g-C₃N₄ using density functional theory, examining the adsorption location, structure, energy, and charge density. Calculations show that metal doping significantly improves As₂O₃ adsorption capacity. Adsorption energy on M₂/g-C₃N₄ (where M₂ denotes a bimetallic atom) exceeds that on M/g-C₃N₄ (where M denotes a monometallic atom) due to bimetallic atoms' synergistic and electronic effects. Co₂ introduction has the most obvious effect, with an adsorption energy of -565.1 kJ mol^-1-4.36 and 2.25 times higher than that of pure g-C₃N₄ and monoatomic Co doping, respectively. This indicates that bimetallic doping favors As₂O₃ adsorption. Projected density of states and adsorption process analysis further verify the excellent performance of bimetallic-doped g-C₃N₄. This DFT study contributes to understanding the atomic-scale adsorption mechanism and aids in the rational design of high-performance adsorbents.