Microwave-assisted selective deoxygenation of layer- and chain-containing oxides

Abstract

Very rapid (within 5 min), selective, single-step deoxygenation of layer- and chain-containing oxides, MoO₃, CrO₃, V₂O₅, α-VOPO₄·2H₂O and Ag₆Mo₁₀O₃₃ has been accomplished using graphitic carbon in a microwave-assisted reaction. The products were found to be MoO₂, Cr₂O₃, VO₂, VPO₄ and a mixture of (Ag + MoO₂), respectively. Products were characterised by X-ray diffraction (XRD), differential scanning calorimetry (DSC), IR and electron paramagnetic resonance (EPR) spectroscopies. Although conventional methods of preparing these materials are tedious, the present method is simple, fast and yields very homogeneous products of good crystallinity. Our results reveal that while layer- and chain-containing oxides undergo rapid microwave-assisted carbothermal reduction, the non-layered materials do not. The high structural selectivity of these reactions is suggestive of the topochemical nature of the fast reduction process.