Hydrogen is an environmentally friendly alternate fuel to the conventional fossil fuels. It can be produced electrochemically from seawater which is an abundant source. But to make the production cost cheap advanced catalysts have to be developed to increase the efficiency of the electrochemical hydrogen reaction. The most efficient catalysts for this purpose is made from platinum group metals which are expensive.

Researchers at Stanford University in California have developed a new catalyst for hydrogen evolution reaction. The catalyst is made of molybdenum disulphide nanoparticles grown on graphene as an alternative to expensive platinum.

Flexible graphene oxide sheets could provide an ideal substrate for MoS2 nanoparticles and the resulting MoS2/reduced graphene oxide hybrid has a very high electrocatalytic activity for the hydrogen evolution reaction that is superior to MoS2 catalysts synthesized without graphene. This is shown by the very high value of the measured Tafel slope which indicates the rate of a electrochemical reaction. The activity of the developed hydrogen evolution reaction catalyst is very high compared to previous MoS2 catalysts. This effect is attributed to the large number of catalytic edge sites on the tiny MoS2 nanoparticles, the material couples well to the underlying graphene network, shows a small overpotential and a large current density and it remains active even after 1000 cycles.

The researchers made their hybrid catalysts in a solvothermal reaction of ammonium tetrathiomolybdate – (NH4)MoS4 – and hydrazine in a dimethylformaide solution of graphene oxide at 200 °C overnight. During this process, graphene oxide was reduced to RGO, and (NH4)MoS4 was reduced to MoS2 on RGO by hydrazine. The researchers are exploring the possibility of improving and integrating it into photoelectrochemical reactions. While traditional catalysts such as platinum and palladium, although very efficient are not cheap, the performance and low cost of the MoS2/RGO hybrid catalyst makes it a very good replacement of these precious metals for large-scale industrial and domestic applications.