Colloidal\nSynthesis of 1T-WS₂ and 2H-WS₂ Nanosheets: Applications\nfor Photocatalytic Hydrogen Evolution

Abstract

In recent years, a lot of attention\nhas been devoted to monolayer\nmaterials, in particular to transition-metal dichalcogenides (TMDCs).\nWhile their growth on a substrate and their exfoliation are well developed,\nthe colloidal synthesis of monolayers in solution remains challenging.\nThis paper describes the development of synthetic protocols for producing\ncolloidal WS₂ monolayers, presenting not only the usual\nsemiconducting prismatic 2H-WS₂ structure but also the\nless common distorted octahedral 1T-WS₂ structure, which\nexhibits metallic behavior. Modifications of the synthesis method\nallow for control over the crystal phase, enabling the formation of\neither 1T-WS₂ or 2H-WS₂ nanostructures. We study\nthe factors influencing the formation of the two WS₂ nanostructures,\nusing X-ray diffraction, microscopy, and spectroscopy analytical tools\nto characterize them. Finally, we investigate the integration of these\ntwo WS₂ nanostructured polymorphs into an efficient photocatalytic\nhydrogen evolution system to compare their behavior.