Two-dimensional Nanomaterials in Thermocatalytic Reactions: Transition Metal Dichalcogenides, Metal Phosphorus Trichalcogenides and MXenes

ABSTRACT Two-dimensional (2D) nanomaterials have attracted intense interest since the successful discovery of mechanically exfoliated graphene. Their unique chemical, mechanical, optical, and electrical properties have been exploited in a wide range of applications, including electrical/optoelectrical devices, solar cells, sensors, membranes, and electro/photocatalysis. However, the application of 2D nanomaterials as thermocatalysts is much less common such that a wide range of questions regarding their activity and stability remain. Herein, the application of 2D transition metal dichalcogenides (TMDs), metal phosphorus trichalcogenides (MPTs) and MXenes as thermocatalysts is reviewed. The data indicate that in most cases, reducing the thickness of the catalyst to that of a single or a few layers of atoms, leads to a significant improvement in product selectivity and reaction rate. However, challenges remain, including the low thermal and chemical stability of 2D nanostructures at typical thermocatalytic operating conditions, facile poisoning of the exposed surface, and rapid loss of activity. In addition, the synthesis procedures for 2D nanostructures are complex, making reproducibility and scale-up difficult. This review identifies knowledge gaps to draw attention to these unique materials that have the potential for significant impact as thermocatalysts.