Adsorbate and defect effects on electronic and transport properties of gold nanotubes

TL;DR

This study uses first-principles calculations to analyze how adsorbates and defects affect the electronic and transport properties of gold nanotubes, revealing potential for chemical sensing applications.

Contribution

It provides detailed insights into the effects of CO, O adsorbates, and various defects on the conductance of Au nanotubes, highlighting their impact on electronic properties.

Findings

CO adsorption decreases conductance by up to 0.9G0.

O atoms cause around 2G0 conductance drop.

Defects reduce conductance by approximately 1G0.

Abstract

First-principles calculations have been performed to study the effects of adsorbates (CO molecules and O atoms) and defects on electronic structures and transport properties of Au nanotubes (Au(5, 3) and Au(5, 5)). For CO adsorption, various adsorption sites of CO on the Au tubes were considered. The vibrational frequency of the CO molecule was found to be very different for two nearly degenerate stable adsorption configurations of Au(5, 3), implying the possibility of distinguishing these two configurations via measuring the vibrational frequency of CO in experiments. After CO adsorption, the conductance of Au(5, 3) decreases by 0.9G0 and the conductance of Au(5, 5) decreases by approximately 0.5G0. For O-adsorbed Au tubes, O atoms strongly interact with Au tubes, leading to around 2G0 of drop in conductance for both Au tubes. These results may have implications for Au-tube-based chemical sensing. When a monovacancy defect is present, we found that, for both tubes, the conductance decreases by around 1G0. Another type of defect arising from the adhesion of one Au atom is also considered. For this case, it is found that, for the Au(5, 3) tube, the defect decreases the conductance by nearly 1G0, whereas for Au(5, 5), the decrease in conductance is only 0.3G0.