Fabrication of La2O3 Uniformly Doped Mo Nanopowders by Solution Combustion Synthesis Followed by Reduction under Hydrogen

Abstract

This work reports the preparation of La2O3 uniformly doped Mo nanopowders with the particle sizes of 40–70 nm by solution combustion synthesis and subsequent hydrogen reduction (SCSHR). To reach this aim, the foam-like MoO2 precursors (20–40 nm in size) with different amounts of La2O3 were first synthesized by a solution combustion synthesis method. Next, these precursors were used to prepare La2O3 doped Mo nanopowders through hydrogen reduction. Thus, the content of La2O3 used for doping can be accurately controlled via the SCSHR route to obtain the desired loading degree. The successful doping of La2O3 into Mo nanopowders with uniform distribution were proved by X-ray photon spectroscopy and transmission electron microscopy. The preservation of the original morphology and size of the MoO2 precursor by the La2O3 doped Mo nanopowders was attributed to the pseudomorphic transport mechanism occurring at 600 °C. As shown by X-ray diffraction, the formation of Mo2C impurity, which usually occurs in the direct H2 reduction process, can be avoided by using the Ar calcination-H2 reduction process, when residual carbon is removed by the carbothermal reaction during Ar calcination at 500 °C.

Construction of Ln2O3@C Nanosheets for Electrocatalytic Nitrogen Reduction to Ammonia

“…The high-resolution TEM image presented the lattice spacing of 0.341 and 0.306 nm, corresponding to the (100) and (002) lattice fringes of La 2 O 3 , proving the formation of La 2 O 3 after the calcination at high temperature. Meanwhile, the selected area electron diffraction (SAED) pattern exhibits a set of diffraction rings, which can be assigned to (100), (102), (110), and (112) planes of La 2 O 3 , further proving the formation of La 2 O 3 . HAADF image and EDS mapping of La 2 O 3 @C-800 showed a homogenous distribution of La, C, and O in the La 2 O 3 @C-800 nanosheet, implying La 2 O 3 nanoparticles are uniformly dispersed in the carbon matrix.…”

High-energy ball milling and spark plasma sintering of molybdenum - lanthanum oxide (Mo-La2O3) and molybdenum – lanthanum zirconate (Mo-La2Zr2O7) composite powders

“…typically covered with thin oxide due to high reactivity of the highlydeformed material with oxygen (similarly to that like Mo nanoparticles are easily oxidized in air and show the evidence of MoO 2 , MoO 3 and Mo 4 O 11 oxides [27]), therefore, the solid state reaction in the La 2 O 3 -MoO 3 -Mo system occurs during thermal treatment with the formation of LaMo 5 O 8 compound as a reaction product [28].…”