Australian group develops tunable nitrogen-doping of 2D MoS2
Sol-gel doping method is simple, efficient and scalable
2D MoS2 has attracted considerable interest because of its direct bandgap, high electron mobility, stable chemical properties and its graphene-like honeycomb lattice which make it a candidate for future electronic and energy storage applications. While various methods have been developed to prepare 2D MoS2, none has been reported capable of incorporating nitrogen content into MoS2 nanosheets, especially in a controllable manner.
Recently, Zhou W. et al reported nitrogen self-doped MoS2 produced by separated nitridation and sulphuration process showing outstanding performance as catalysis for hydrogen evolution reaction. However, it requires a complicated and multi-step process and it is unlikely to control the nitrogen doping on the final product.
Now a team from Deakin University in Australia, has reported in Nature Scientific Reports a method for the synthesis of MoS2 nanosheets with tunable, high concentration and in-situ nitrogen-doping using a simple sol-gel process, that they say is efficient and scalable.
They synthesised the MoS2 nanosheets using a sol-gel method with MoCl5 and thiourea as starting materials. By adjusting the ratio of MoCl5 and thiourea, the team was able to produce MoS2 nanosheets with almost the same morphology and structure but different nitrogen doping level.
MoS2 nanosheets made in this way show a porous structure formed by curled and overlapped nanosheets with well-defined edges. Analysis of the nanosheets shows that they have an enlarged interlayer distance and high specific surface area. X-ray photoelectron spectroscopy analysis shows the nanosheets have Mo-N bond indicating successful nitrogen doping. The nitrogen content of the product is evenly distributed and can be modulated by adjusting the ratio of starting materials easily within the range from ca. 5.8 to 7.6 at%.
The researchers say that this synthesis approach may open up new paths to non-metal element doping and functionalisation of MoS2 for other applications such as catalyst and energy storage and conversion devices including lithium ion batteries.
'In-situ and tunable nitrogen-doping of MoS2 nanosheets', by Si Qin et al, Nature Scientific Reports 4, Article number: 7582 doi:10.1038/srep07582
