Synthesis of bilayer MoS2 nanosheets by green chemistry approach and its application in triboelectric and catalytic energy harvesting

Recently, 2D materials are being explored as attractive candidate materials for mechanical energy harvesting by employing the triboelectric effect. However, in this work, development of flexible paper-based triboelectric nanogenerators has been reported in 2-, 5-and 9-layered MoS2 nanosheets (MNSs). The syntheses of bilayered MNSs have been carried out by using a rarely reported natural surfactant (aqueous extract of Washnut, viz.) assisted simple bath ultrasonication process. The development of triboelectric power cells (TPCs) by using bilayer MNSs has also not been reported earlier and it has been found that it is exhibiting the best performance. The maximum values of open-circuit voltage (V-oc) and power density of -10.20 V and -2.55 mW/m(2), respectively, are obtained in bilayer MNSs based TPC. It is found that the fabricated device can charged up an external capacitor up to the maximum voltage of 0.52 V within 25s. Also, due to the highest absorbance of bilayer MNSs in the visible region, it has been found to be acting as the most effective photocatalytic material for removal of MB dye from water even under the visible light excitation. In another experiment, the bilayer MNSs is found to be exhibiting superior catalytic activity in the hydrogen evolution reaction (HER), and the highest value of the Tafel slope for bilayer MNSs is obtained as similar to 49 mV/decade. Thus, it is envisioned that this work will open up new vistas of easy and ecofriendly processes for synthesis of 2D MoS2 nanosheets for their potential applications in energy harvesting by using triboelectric and as well as catalytic processes. (C) 2020 Elsevier B.V. All rights reserved.