Facile one-step synthesis of g–C3N4–supported WS2 with enhanced lithium storage properties

Abstract

Composites of WS2 nanosheets integrated with g-C3N4 were synthesized using a facile solid-state reaction method from a precursor mixture of tungstic acid and thiourea under an inert gas, and denoted as WS/CN-x where x is the weight ratio of thiourea/tungstic acid. In the composites, highly exfoliated-WS2 sheets were dispersed evenly onto the g-C3N4 matrix. The intimate contact between the WS2 nanosheets and g-C3N4 flakes was confirmed using TEM, FTIR, and XPS analyses. Among the composites, WS/CN-5 exhibited excellent lithium storage performance. Even at a high current density of 1000 mA g−1, the composite electrode delivered a reversible capacity of 622.7 mAh g−1 after 400 charge-discharge cycles. The enhanced lithium storage capacity of the composite stems from the even distribution of WS2 nanosheets as active electrode material on the g-C3N4 matrix. The presence of g-C3N4 as a supporting framework for the WS2 nanosheets significantly improved the kinetics of the charge transport process and alleviated the strains caused by the volume change in the nanostructured WS2 during the charge-discharge process. In addition, the enhanced lithium storage performance of the WS2/g-C3N4 composites was also attributed to the high contribution of the pseudocapacitive effect.