Thermal Decomposition of Nanostructured Bismuth Subcarbonate

Abstract

Nanostructured (BiO)2CO3 samples were prepared, and their thermal decomposition behaviors were investigated by thermogravimetric analysis under atmospheric conditions. The method of preparation and Ca2+ doping could affect the morphologies of products and quantity of defects, resulting in different thermal decomposition mechanisms. The (BiO)2CO3 nanoplates decomposed at 300–500 °C with an activation energy of 160–170 kJ/mol. Two temperature zones existed in the thermal decomposition of (BiO)2CO3 and Ca-(BiO)2CO3 nanowires. The first one was caused by the decomposition of (BiO)4(OH)2CO3 impurities and (BiO)2CO3 with surface defects, with an activation energy of 118–223 kJ/mol, whereas the second one was attributed to the decomposition of (BiO)2CO3 in the core of nanowires, with an activation energy of 230–270 kJ/mol for the core of (BiO)2CO3 nanowires and 210–223 kJ/mol for the core of Ca-(BiO)2CO3 nanowires. Introducing Ca2+ ions into (BiO)2CO3 nanowires improved their thermal stability and accelerated the decomposition of (BiO)2CO3 in the decomposition zone.

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“…The peak temperature was determined using the DTG peak, where the maximum decomposition rate was obtained. The results show that there is a weight loss zone in the thermogravimetric curve of BOB/BOC at 300–550 °C, which is the mass loss zone of BOC, and the mass loss is 5.1%. ,, The decomposition equation is as follows: …”

“…In comparison to BOB, the peaks observed at 529.94 and 531.1 eV in the BOB/BOC spectrum correspond to lattice oxygen species of Bi−O and C−O, respectively. 37 Additionally, the binding energy observed at 532.8 eV can be attributed to the presence of surface-adsorbed O−H groups. 23 The decrease in binding energy for the Bi−O bond in BOB/BOC suggests a strong charge transfer between BOB and BOC, while an increase in binding energy is observed for the C−O bond.…”