Binding of Trivalent Arsenic onto the Tetrahedral
Au<sub>20</sub> and Au<sub>19</sub>Pt Clusters: Implications in Adsorption
and Sensing
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Abstract
The
interaction of arsenic(III) onto the tetrahedral Au<sub>20</sub> cluster
was studied computationally to get insights into the interaction
of arsenic traces (presented in polluted waters) onto embedded electrodes
with gold nanostructures. Pollutant interactions onto the vertex,
edge, or inner gold atoms of Au<sub>20</sub> were observed to have
a covalent character by forming metal–arsenic or metal–oxygen
bonding, with adsorption energies ranging from 0.5 to 0.8 eV, even
with a stable physisorption; however, in aqueous media, the Au–vertex–pollutant
interaction was found to be disadvantageous. The substituent effect
of a platinum atom onto the Au<sub>20</sub> cluster was evaluated
to get insights into the changes in the adsorption and electronic
properties of the adsorbent–adsorbate systems due to chemical
doping. It was found that the dopant atom increases both the metal–pollutant
adsorption energy and stability onto the support in a water media
for all interaction modes; adsorption energies were found to be in
a range of 0.6 to 1.8 eV. All interactions were determined to be accompanied
by electron transfer as well as changes in the local reactivity that
determine the amount of transferred charge and a decrease in the HOMO–LUMO
energy gap with respect to the isolated substrate