Mesoporous α-Fe2O3/ZnO heterojunction with a synergistic effect for rapid and efficient reduction of mercury ions

Abstract

Ease construction of mesoporous α-Fe2O3/ZnO heterostructures at diverse percentages of Fe2O3 was successfully achieved through the sol-gel method. The photoreduction of Hg(II) ions was conducted over newly synthesized mesoporous α-Fe2O3/ZnO heterostructures in the presence of formic acid as holes scavenger. 3%α-Fe2O3/ZnO heterojunction was exhibited remarkable improvement in the Hg(II) photoreduction through visible light exposure, with a photocatalytic efficiency ∼100% within 50 min, which was about 24 and 14 times higher than that of pristine ZnO NPs and commercial TiO2, respectively. The apparent rate constant of mesoporous 3% α-Fe2O3/ZnO photocatalyst was better 65 and 36 times than that of pristine ZnO NPs and commercial TiO2, respectively. The enhancement α-Fe2O3/ZnO heterojunction for Hg(II) photoreduction was ascribed by the synergistic effect, large surface/volume ratio with notably porous structure and the extended absorption capability with the improved separation of charge carriers efficiency due to fabrication of a heterojunction system. The results provide a favourable approach to fabricate mesoporous α-Fe2O3/ZnO heterojunction system with desirable potential photocatalysis applications.