Bismuth oxide, CAS number 1304-76-3, has five polymorph modifications, known as α-, β-, γ-, δ-, and ε-Bi2O3. The monoclinic form α phase of ambient temperature and the δ phase of high temperature are both structurally stable. At a temperature higher than 710 °C, α phase is converted into the cubic δ phase that has a defective structure with random oxygen vacancies. The others are high-temperature metastable phases. Each polymorph possesses distinct crystalline structures and physical properties. γ-Bi2O3 phase, having the sillenite structure, is optically active in electro-optic devices. At 300 K, the band gap of monoclinic α-Bi2O3 is equal to 2.85 eV, while that of tetragonal β-phase is 2.58 eV.

Bismuth oxide shows great potential as anode materials for lithium-ion batteries (LIBs), owing to its high theoretical capacity of 690 mA h g−1. Furthermore, CQD−Bi2O3 composite exhibited good electrochemical activity and delivered a discharge capacity as high as 1500 mA h g−1 at 0.2 C rate. The supercapacitor properties of the CQD−Bi2O3 composite electrode revealed good reversibility and a high specific capacity of 343 C g−1 at 0.5 A g−1 in 3 M KOH. The asymmetric device using the CQD−Bi2O3 and reduced graphene oxide as the binary anode materials delivered a maximum energy density of 88 Wh kg−1 at a power density of 2799 W kg−1, while the power density reached a highest value of 8400 W kg−1 at the energy density of 32 Wh kg−1.

Technical Data

Bismuth Oxide (Bi2O3) Nanopowder