Complexation Reaction-Based Two-Dimensional Luminescent Crystalline Assembly of Atomic Clusters for Recyclable Storage of Oxygen

Abstract

In this work, we report storage of oxygen in two-dimensional (2D) crystalline nanosheets comprising luminescent gold nanoclusters (Au NCs). Complexation reaction between Au NCs (stabilized by l-phenylalanine and mercaptopropionic acid) and zinc ions led to the formation of crystalline assembly of Au NCs. The crystalline nature of the assembly of Au NCs was confirmed through transmission electron microscopy (TEM), high-resolution TEM, and selected area electron diffraction (SAED) analysis. Atomic force microscopy (AFM) analysis, in conjunction with field emission scanning electron microscopy (FESEM) analysis, confirmed the 2D nature of the assembly of the Au NCs. The 2D crystalline nanosheets formed out of reaction between Au NCs and Zn2+ were found to be of near-uniform thickness, with an average value of 3.8 ± 1.65 nm. These 2D nanosheets constituting of hierarchically organized Au NCs were further used for reversible storage of oxygen at ambient conditions of 20 °C and 20 bar pressure.