Understanding the characteristics, enhanced optical and photoelectrochemical performance of copper-loaded titania nanotubes synthesized via successive ionic layer adsorption reaction

Abstract

The physico-chemical, optical and photoelectrochemical (PEC) characteristics of copper sensitized titania nanotubes (CuTNT) nanocomposites are still not well understood despite numerous conducted studies. In the present study, copper sensitized titania nanotubes (CuTNT) were prepared using customized Successive Ionic Layer Adsorption Reaction (SILAR) method. The foremost aim is to investigate the aforestated characteristics and consolidate the results to propose mechanisms to elucidate CuTNT’s enhanced optical and PEC performance. Such mechanisms are of particular interest because a better understanding of them would essentially translate to advances in improved CuTNT production and use, especially in regard to PEC applications. We, therefore, attempt to shed more light on its characteristics by employing electron microscopies, X-ray powder diffraction and X-ray photoelectron spectroscopy techniques. Well-ordered crystalline TNT was successfully obtained via anodization in the mixture of ethylene glycol and water mixed with NH4F. CuTNTs were prepared at various concentrations, SILAR cycles and immersion times. CuTNT/20 min of fixed 20 mM and 3 SILAR cycles showed enhanced photoconversion efficiency of almost 2.7 times higher compared to pure TNT due to electron-trap center effect introduced by Cu, reduced band gap energy from 3.26 eV of pure TNT to 2.75 eV, enhanced visible light reactivity and balanced distribution within TNT.