Nanometer-Sized MoS2 Clusters on Graphene Flakes for Catalytic Formic Acid Decomposition

MoS2 was deposited on graphene flakes via decomposition of MoS3 in vacuum at different temperatures (500-800 degrees C). The materials obtained were tested for catalytic formic acid decomposition, giving mainly hydrogen and carbon dioxide. According to atom-resolved transmission electron microscopy study, a considerable amount of MoS2 clusters with a mean size of 1 nm was formed on the graphene surface at 500 degrees C. Simulation of the structure of a cluster revealed the presence of Mo-edge atoms. Raising the preparation temperature up to 800 degrees C led to agglomeration of MoS2 clusters and formation of thin crystalline MoS2 particles 2030 nm in size. The sample enriched with the MoS2 clusters showed 6 times higher catalytic activity at 160 degrees C than the sample with the crystalline MoS2 particles. This demonstrates that the observed nanometer-sized MoS2 clusters are responsible for catalysis.