One-step route to α-Bi2O3/BiOX (X = Cl, Br) heterojunctions with Bi2O3 ultrafine nanotubes closely adhered to BiOX nanosheets

Intrinsic point defects and the n- and p-type dopability in α- and β-Bi2O3 photocatalysts

“…75,81,82 It is challenging to provide considerable n-type carriers even at the experimental preparation temperature of around 673 K. 23 Therefore, the native point defects cannot reasonably explain the intrinsic n-type conductivity character of α-Bi 2 O 3 in experiments. 23–25…”

“…In fact, it is found that H bonds strongly with the nearest O with a bond length of around 1 Å, and a stable structure is formed after H incorporation. Therefore, it is suggested that the observed unintentional n-type conductivity character in experiments 23–25 for α-Bi 2 O 3 should principally arise from the unintentional H interstitials. In these intrinsic n-type semiconductor cases of ZnO 81,82 and GaInO 3 , 75 the native defects also cannot provide the n-type carriers because of the high formation energies or the deep transition levels.…”

“…15 Moreover, α-Bi 2 O 3 has an appropriate band gap of 2.8 eV 15–22 and was usually reported as a p-type semiconductor, 16,17,19–22 also was reported as an n-type semiconductor. 23–25 While tetragonal β-Bi 2 O 3 is a metastable high-temperature phase, it can become stable at room temperature through doping or other methods. 26,27 Compared to α-Bi 2 O 3 , β-Bi 2 O 3 has a smaller bandgap (around 2.4 eV), 28,29 and most experimental research showed that β-Bi 2 O 3 is an intrinsic n-type semiconductor.…”