Optical, structural, and catalytic properties of synthesized Cu2O nanocubes

Cu2O nanocubes (CNCs) have been successfully synthesized by simple thermal annealing of hydrothermally synthesized Cu(OH)(2) microstructures (CHMs) at 400 degrees C for 2 h. The transformation of CHMs to CNCs and changes of their nanostructures due to thermal annealing have been confirmed by analyzing transmission electron microscopy and field emission scanning electron microscopy images. The observed structural transformation has been explained by orientational crystallization mechanism. The changes in optical properties of the synthesized materials have been studied by UV-Vis. absorption and photoluminescence (PL) emission data analyses. The PL emission spectra showed the existence of a few emission bands due to the excitonic transitions in different sub-levels of conduction band to the different Cu 3d shells of valence band. CNCs have shown capability in degradation of methylene blue dye with the highest degradation efficiency of 77% within 100 min. The dye degradation process is found to be following the pseudo-first-order reaction pathway with the rate constant of similar to 1.5 x 10(-2) min(-1). In addition, the cyclic voltammetry studies have been performed in the as-prepared samples and it is observed that as-prepared CNCs have exhibited excellent ion diffusion and capacitive behaviors. The diffusion coefficient of CNCs is found to be similar to 17 times higher than that of CHMs. The quasi-rectangular behavior of CV curves of CHMs electrode confirms its capacitive behavior, whereas other electrodes showed faradic behavior. Graphic abstract