Improvement of Bi doping in ZnO nanocrystals by co-doping with Al: crystal geometry calculations and photocatalytic activity

Abstract

In this work we demonstrate enhancement in visible-light photocatalytic activity (PCA) of ZnO nanoparticles (NPs) with minimal attenuation of visible light transmittance. This approach can benefit numerous optoelectronic and photocatalytic applications. ZnO NPs were p-n co-doped with Al and Bi to improve Bi doping into the ZnO crystal. Al- and/or Bi-doped ZnO was coprecipitated by ammonia from aqueous nitrate solutions of Zn2+, Al3+, and Bi3+, followed by microwave heating. Doping concentrations in Al- and Bi- doped ZnO (AZO and BZO) and Al/Bi co-doped ZnO (ABZO) were 1, 3, 5, and 7 mole %. The resulting NPs were characterized by XRD, TEM, EDS, BET, and UV-visible absorption. While EDS shows that almost all added Bi was incorporated into the ZnO, XRD analysis of BZO reveals formation of α-Bi2O3 as a secondary phase due to the poor Bi solubility in ZnO. Co-doping of Al with Bi suppressed α-Bi2O3 formation and increased Bi solubility in ZnO. XRD-based calculations of the lattice constants and deformation strain, stress, and energy all show insertion of Al and/or Bi into the crystal with different extents according to the dopants’ solubilities into ZnO. AZO and BZO NPs had E g lowered by 0.05–1.39 eV and 0.30–0.70 eV, respectively, relative to ZnO. On the other hand, ABZO had E g reductions of only 0.01–0.20 eV due to formation of acceptor-donor complex through co-doping. ABZO gave higher PCA enhancements with respect to E g reductions (Δk photo/–ΔE g) than either AZO and BZO, with values up to 370, 126, and 13 min–1 eV–1, respectively.

Ce, Eu incorporation through doping of ALD-ZnO thin films for enhancing their photoluminescent properties

“…The results indicate that the codoped ZnO electrode is capable of enhancing their sensitivity, in comparison to pristine ZnO [15]. There are studies where codoping, including aluminum and bismuth, led to an improvement in size and shape of the structures compared to the pure ZnO compound [16]. It has also been reported that doping involving lithium and dispersed rare earth oxides over the ZnO compact powders, improve the photoluminscence signal in ZnO, concluding that color depends on the Er 3+ , Tm 3+ , or Eu 3+ dispersed onto the ZnO pellets [17].…”

Metal-doping of halide perovskite nanocrystals for energy and environmental photocatalysis: challenges and prospects

“…126 However, there is no related report about the Bi-doped HPNCs applied in photocatalysis so far even though Bi-doping has been proven an effective way to modify traditional photocatalysts. [141][142][143] In addition to Bi, other trivalent metal dopings such as In 3+ and Au 3+ may also be promising metals in photocatalysis, and deserve the attention of photocatalysis researchers. 78,144 Metal-doped HPNCs hold great potential in photocatalytic applications, but the inferior efficiency still restricts their practical application.…”