Phase transition guided V2O5/β-Bi2O3 Z-scheme heterojunctions for efficient photocatalytic Hg0 oxidation

The incorporation of vanadium during the synthesis process induced a spontaneous and complete thermal phase transition from alpha-Bi2O3 to beta-Bi2O3. This phase transition facilitated the development of intrinsic electric field at the interface between V2O5 and beta-Bi2O3, consequently establishing a novel carrier transfer pathway. As a result, the fabricated V2O5/beta-Bi2O3 heterojunction exhibited an outstanding removal efficiency of over 98 % for gaseous mercury (Hg-0) under UV light, and this efficiency of 95.0 % even after 35 h of testing. Introducing vanadium enhanced the light absorption capacity in the ultraviolet region and effectively separated photoinduced charge carriers. As revealed by density functional theory calculations, the photoinduced electron-hole transfer in the V2O5/beta-Bi2O3 heterojunction followed the Z-scheme mechanism. This mechanism significantly contributed to the long-term stability of photocatalytic Hg-0 removal, even when H2O and NO were present. This study presents a novel material composited by a thermal phase transition technique, aimed at the highly effective and green removal of Hg-0 in the environment.