Cf. Tsang et A. Manthiram, SYNTHESIS OF LOWER-VALENT MOLYBDENUM OXIDES IN AQUEOUS-SOLUTIONS BY REDUCING NA2MOO4 WITH NABH4, Journal of materials chemistry, 7(6), 1997, pp. 1003-1006
Reduction of Na2MoO4 with NaBH4 in aqueous solutions at ambient temper
atures has been investigated systematically by varying the concentrati
on and volume of NaBH4 as well as the reaction pH. The reduction produ
cts have been characterized by X-ray diffraction and differential scan
ning calorimetry (DSC). The reduction yields metastable, amorphous oxi
des of lower-valent molybdenum, which crystallize around 350 degrees C
to give the binary oxide MoO2 and the sodium molybdenum bronze Na0.88
Mo6O17. The relative amounts of MoO2 and Na0.88Mo6O17 formed are corre
lated to the overall reducing power that can be achieved. The concentr
ation and volume of NaBH4, the reaction pH and the changes in the degr
ee of condensation of the molybdate ions are all found to influence th
e overall reducing power.