Core-shell ZnO@Cu2O encapsulated Ag NPs nanocomposites for photooxidation-adsorption of iodide anions under visible light

Iodide anion (I-) is one of the most-problematic radioactive nuclides in used nuclear fuel due to its intrinsic characteristics of a high toxicity and environmental mobility. Therefore, effective and selective elimination of I- from nuclear contaminated solution is highly beneficial for the pollution remediation purposes in the development of nuclear power, but is of significant challenge owing to the extreme conditions of the high acidity, strong ionizing radiation field and high concentration of competing anions. Herein, a novel core-shell ZnO@Cu2O (ZC) encapsulated Ag nanoparticles (Ag NPs) nanocomposites have been fabricated via a facile one step self-assembly process and an environmentally friendly technique. The as-fabricated ZnO@Ag@Cu2O (ZAC) nanocomposites were characterized and applied to capture of I from aqueous solution. Adsorption studies revealed that the ternary nanocomposites showed fast removal kinetics, high photooxidation-adsorption capacity (up to 217.4 mg g(-1) at pH = 3 for ZAC-2), satisfactory selectivity and high acidity resistance. Furthermore, the nanocomposites also exhibited a good reusability, as no significant change in the uptake capacity was observed even after five adsorption-regeneration cycles. Inspired by the superior features, a possible mechanism (chemical adsorption coupled with photooxidations) was proposed based on XRD, XPS and Raman spectra analysis for the pre- and post-adsorbed samples as well as the detailed adsorption experimental evidence.