The sensing mechanism of pristine and transition metals doped Zn12O12, Sn12O12 and Ni12O12 nanocages towards NH3 and PH3: a DFT study

Abstract

From the perspective of environmental safety and human health, it is crucial to develop high-performance sensitive materials that can effectively monitor ammonia (NH₃) and phosphine (PH₃) toxic gases. In this study, we first investigated the adsorption performance of Zn₁₂O₁₂, Sn₁₂O₁₂ and Ni₁₂O₁₂ nanocages towards NH₃ and PH₃. Based on the analysis of adsorption energy, charge transfer and the nearest intermolecular distance, Zn₁₂O₁₂, Sn₁₂O₁₂ and Ni₁₂O₁₂ nanocages exhibit excellent sensitivity toward NH₃ with respect to PH₃. Meanwhile, the gas sensing performance of the NH₃ adsorption system can be improved by applying a positive electric field. Additionally, a humid environment has a great negative impact on the detection of PH₃. Next, the sensing mechanisms of NH₃ on Ti, Cr and Fe-doped nanocages were also analyzed. The cohesive energies are obtained to confirm the stability of doped Zn₁₂O₁₂, Sn₁₂O₁₂ and Ni₁₂O₁₂ nanocages. The results show that Zn₁₁TiO₁₂ and Sn₁₁TiO₁₂ exhibit a more desirable adsorption performance with respect to NH₃ compared with pure Zn₁₂O₁₂ and Sn₁₂O₁₂, along with larger adsorption energy and significant charge transfer. Therefore, Ti doped Zn₁₂O₁₂ and Sn₁₂O₁₂ can be considered as potential candidates for NH₃ detection. This work would be meaningful to reveal a gas sensing mechanism and provide theoretical guidelines for experimentalists to design and synthesis high sensitivity sensors for detecting toxic gases.