A p-n heterojunction PdO/CeO2 photocatalysts with enhanced photocatalytic ability for reduction of Hg(II) ions from aqueous solution

Abstract

Heterostructured photocatalysts represent an essential role in the catalytic redox reactions in wastewater during illumination. In this contribution, p-n heterojunction PdO/CeO2 photocatalysts were constructed with enhanced photocatalytic ability for the reduction of Hg(II) utilizing HCOOH as hole scavengers under visible light. PdO NPs were uniformly spread on the mesoporous CeO2 surface, to act as potential separation centers of electrons and holes. The synthesized PdO/CeO2 nanocomposites exhibited an excellent photocatalytic ability, contrasted to the bare CeO2 NPs. The photocatalytic ability of PdO/CeO2 nanocomposites for reduction of Hg(II) has existed in the trends of 2%PdO ≥1.5%PdO >1%PdO >0.5 % PdO/CeO2 nanocomposites > bare CeO2 NPs. A photocatalytic ability of 100 % for Hg(II) reduction was achieved within 40 min utilizing 1.5 % PdO/CeO2 nanocomposites, which was 2.2 folds greater than that of bare CeO2 NPs. The rate constant of 1.5 % PdO/CeO2 nanocomposite (0.106 min−1) is more 9.9 times than that CeO2 NPs (0.0107 min−1). The enhancement photocatalytic ability of PdO/CeO2 can be interpreted to the wide surface area, narrow bandgap, numerous active sites, fast mobility, efficient diffusion of Hg(II), and the high separation rate of photocarriers. Considering the promotion photocatalytic ability of heterojunction PdO/CeO2 nanocomposites, the heterostructure photocatalyst is of magnificent importance to the photocatalytic redox reactions and exhibits a significant effect on our human health and ecological environment.