Microwave driven synthesis of tungsten sulfide nanosheets: An efficient electrocatalyst for oxygen reduction reaction

The transition metal chalcogenide (TMC) nanosheets are a new class of 2D materials that play an increasingly important role in the variety of electronic devices. In the present work, tungsten sulfide (WS 2 ) nanosheets were successfully synthesized by the one-step microwave irradiation method (850 W, Anton paar monowave 200) without using any templates. The structural formation of the WS 2 was primarily confirmed by the X-ray powder diffraction analysis and the morphology was observed by the field emission scanning electron microscopy. The Raman, X-ray photoelectron, and energy-dispersive X-ray spectroscopies were used to investigate the ordered nature and elemental composition of the WS 2 nanosheets. The synthesized WS 2 showed amendable electrocatalytic activity for the oxygen reduction reaction in an alkaline medium with the onset potential of 0.82 V and the number of electrons transferred for the reaction as 3.29. All of these facts point to the WS 2 nanosheets being a promising noble-metal -free ORR cathode catalyst for the fuel cells.