Phosphorene-Supported Au(I) Fragments for Highly Sensitive Detection of NO.

The fabrication and application of single-site heterogeneous reaction centers are new frontiers in chemistry. Single-site heterogeneous reaction centers are analogous to metal centers in enzymes and transition-metal complexes: they are charged and decorated with ligands and would exhibit superior reactivity and selectivity in chemical conversion. Such high reactivity would also result in significant response, such as a band gap or resistance change, to approaching molecules, which can be used for sensing applications. As a proof of concept, the electronic structure and reaction pathways with NO and NO of Au(I) fragments dispersed on phosphorene (Pene) were investigated with first-principle-based calculations. Atomic-deposited Au atoms on Pene (Au-Pene) have hybridized Au states in the bulk band gap of Pene and a decreased band gap of 0.14 eV and would aggregate into clusters. Passivation of the Au hybrid states with -OH and -CH forms thermodynamically plausible HO-Au-Pene and HC-Au-Pene and restores the band gap to that of bulk Pene. Inspired by this, HO-Au-Pene and HC-Au-Pene were examined for detection of NO and NO that would react with -OH and -CH, and the resulting decrease of band gap back to that of Au-Pene would be measurable. HO-Au-Pene and HC-Au-Pene are highly sensitive to NO and NO, and their calculated theoretical sensitivities are all 99.99%. The reaction of NO with HO-Au-Pene is endothermic, making the dissociation of product HNO more plausible, while the barriers for the reaction of CH-Au-Pene with NO and NO are too high for spontaneous detection. Therefore, HO-Au-Pene is not eligible for NO sensing and CH-Au-Pene is not eligible for NO and NO sensing. The calculated energy barrier for the reaction of HO-Au-Pene with NO is 0.36 eV, and the reaction is about thermal neutral, suggesting HO-Au-Pene is highly sensitive for NO sensing and the reaction for NO detection is spontaneous. This work highlights the potential superior sensing performance of transition-metal fragments and their potential for next-generation sensing applications.