A Floatable Piezo-Photocatalytic Platform Based on Semi-Embedded ZnO Nanowire Array for High-Performance Water Decontamination

HIGHLIGHTS: ZnO nanowires were securely immobilized onto a floatable photocatalytic platform, which had a uniform diameter (55 ± 5 nm) and length (1.5 ± 0.3 μm). An additional 20% of the probe pollutant (methylene blue) was degraded by piezocatalysis-assisted photocatalytic degradation. The crude oil pollutant was decomposed up to 20% within 6 h. ABSTRACT: Photocatalytic degradation attracts considerable attention because it is a promising strategy to treat pollutants from industrial and agricultural wastes. In recent years, other than the development of efficient photocatalysts, much effort has been devoted to the design of reliable and inexpensive photocatalytic platforms that work in various environment conditions. Here, we describe a novel photocatalytic platform that is able to float and freely move atop water while performing photodegradation. Compared to common platforms, such as slurry reactors and immobilized photoreactors, the proposed platform is advantageous in terms of easy recycling and energy saving. Furthermore, the special configuration resulting from a two-step synthesis route, semi-embedded photocatalysts, addresses some of the remaining challenges, for instance, the contamination from the loose photocatalysts themselves. For the probe pollutant, methylene blue (MB), a reproducible and remarkable degradation activity of the platform, is observed and the effect of two primary factors, including surface area of the catalyst and mass transfer rate, is investigated. Besides, the piezo-photocatalysis effect, serving as an additional functionality, is confirmed to further improve the degradability of the platform, which offers an additional 20% of degraded MB. At last, the promising result of the degradation toward crude oil reveals the possibility of the platform to be used in gasoline pollution treatment. [Image: see text]