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

Ease construction of mesoporous alpha-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 alpha-Fe2O3/ZnO heterostructures in the presence of formic acid as holes scavenger. 3%alpha-Fe2O3/ZnO heterojunction was exhibited remarkable improvement in the Hg(II) photoreduction through visible light exposure, with a photocatalytic efficiency similar to 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% alpha-Fe2O3/ZnO photocatalyst was better 65 and 36 times than that of pristine ZnO NPs and commercial TiO2, respectively. The enhancement alpha-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 alpha-Fe2O3/ZnO heterojunction system with desirable potential photocatalysis applications.

Automated summary

The synthesis of mesoporous alpha-Fe2O3/ZnO heterostructures with different Fe2O3 percentages through the sol-gel method allowed for effective photoreduction of Hg(II) ions. Particularly, the 3% alpha-Fe2O3/ZnO heterojunction exhibited significantly improved photocatalytic efficiency for Hg(II) photoreduction under visible light exposure, surpassing pristine ZnO NPs and commercial TiO2. The success was attributed to the synergistic effect, large surface/volume ratio, porous structure, and enhanced charge carrier separation efficiency of the heterojunction system.