Ultrahigh degradation efficiency of AB type in-plane reverse polarization WS2 nano sheets in dark by piezo-catalyst effect

Abstract

In the past decades, organic pollutants have become an important issue affecting life. In previous works, despite the photocatalytic degradation of organic pollutants have been extensively studied and applied, the period of catalytic effect is too long and the catalytic efficiency is difficult to converge, due to the limitation of photocatalytic conditions. In this work, the WS2 piezoelectric catalytic materials were proved to be highly efficient and reusable. Herein, it is reported that a-WS2 (150 °C), b-WS2 (160 °C), and c-WS2 (180 °C) catalysts degrade MB, with efficiencies of 99.7%, 72.2%, and 49.3%, respectively. The results show that cyclic stretching and releasing of thin WS2 flakes with an odd number atomic layers, produces oscillating piezoelectric volt-age, resulting in ultra-high catalytic efficiency. When external mechanical stress is applied, the WS2 nanosheets structure can disperse a large amount of hydroxyl radicals (OH) and superoxide radicals (O2−) in the solution. The high repetition rate of WS2 was also proved by cyclic experiments. In this work, the shortcomings of conventional photocatalysis were overcome by employing a novel AB type in-plane reverse polarization WS2 nano network, which is activated through the application of an external force.