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

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.