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 (WS2) 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 WS2 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 WS2 nanosheets. The synthesized WS2 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 WS2 nanosheets being a promising noble-metal -free ORR cathode catalyst for the fuel cells.