TM-Doped B₁₂N₁₂ Nanocage (TM = Fe, Co, and Ni) As a Sensitive and Selective CO Gas Sensor: A Theoretical Study

The development of efficient sensors for hazardous gases remains a critical challenge, driving intense interest within the scientific community. In this theoretical investigation, the interactions between carbon monoxide (CO) and pristine B₁₂N₁₂, as well as transition-metal-doped nanocages (FeB₁₁N₁₂, CoB₁₁N₁₂, and NiB₁₁N₁₂), were examined using DFT at the B97D/6-31G-(d,p) level. The results reveal that CO is weakly physisorbed on the pristine B₁₂N₁₂ nanocage, indicating limited sensing capability. In contrast, metal doping markedly enhances adsorption strength and sensing performance, with the NiB₁₁N₁₂ system standing out for its moderate adsorption energy (E _ads = -0.76 eV) and high electronic sensitivity (80.9%). Beyond adsorption strength, selectivity coefficient analysis combined with molecular dynamics simulations demonstrates that NiB₁₁N₁₂ can effectively discriminate CO from common interfering gases, including CO₂, N₂O, CH₄, and H₂. Additionally, compared with other systems in the literature, NiB₁₁N₁₂ exhibits better sensitivity and selectivity, even under dry conditions or in very low humidity. Overall, this study advances the field by establishing NiB₁₁N₁₂ as a promising material for the selective detection of CO, thereby offering valuable insights for experimental fabrication and real-world applications.