Self-assembled silver-decorated titania and zinc oxide nanowires for photocatalytic dye degradation

Fast fashion and expansion into new markets, mainly in Asia, have drastically increased the demand for dyes. A significant proportion of toxic dyes enter the environment unfiltered, causing severe damage, such as disrupting photosynthesis and respiration in aquatic organisms even at low concentrations of 1 mg/L. Reducing the concentration or entirely removing those dyes is therefore essential to protect aquatic life and ensure clean drinking water. Here, we present a novel approach for fabricating photocatalytic ZnO and TiO 2 nanostructures with high photocatalytic activity on a large scale using metastable atomic layer deposition (MS-ALD). Dose times and number of cycles were optimized to achieve structures with superior optical performance. Mean absorption rates of 79 % and 68 % were achieved over a broad spectral range (200 nm–2500 nm) for TiO 2 and ZnO nanostructures, respectively. Optimized structures were used to test the degradation of the model analyte Acid Orange 7 (AO7) under UV light. ZnO structures demonstrated high activity, significantly reducing AO7 concentration, whereas TiO 2 structures showed no photocatalytic activity. The inactivity of TiO 2 could be attribute to numerous effects such as the absence of a crystalline phase or fast charge recombination. • Large-scale synthesis of catalytic active nanostructures using MS-ALD. • Photocatalytic degradation of the dye Acid Orange 7 under UV-light. • Broadband absorption above 79 % from 220 nm to 2500 nm. • Self-assembled 3D ALD synthesis with structures height over 2 μm.