Two step mechanochemical synthesis of Nb doped MgO rock salt nanoparticles and its application for hydrogen storage in MgH2

•Nb doped MgO was synthesized from NbO2/MgH2 and MgNb2O6/MgH2.•The particle size of Nb doped MgO is lesser than 100 nm.•Nb substituted MgO is catalytically active for MgH2.•Small amount of NbOx (x < 1) also exists along with Nb doped MgO.

In the present study, we demonstrate two mechanochemical approaches suitable for the bulk scale synthesis of catalytically active Nb doped MgO rock salt nanoparticles. In the first method, Nb2O5 initially was reduced to NbO2 by MgH2 and then transformed to MgxNbyOx+y. In the second method, MgO and Nb2O5 were initially combined to make MgNb2O6 and then converted to MgxNbyOx+y. The DSC-TG and Sievert's volumetric analysis suggest that the end product, MgxNbyOx+y, is catalytically more active in comparison to all other oxide phases involved in the reaction, such as Nb2O5, NbO2 and MgNb2O6.