Preparation of Ni/Ce Composite Photocatalytic CO2 Heterojunction by Treating Electroplating Nickel Wastewater

Abstract

AbstractIn the past few years, it was discovered that Ni(OH)2 is an effective photocatalyst for CO2 as a chemical fuel catalyst. Ni(OH)2 nanosheets were prepared by simple wet treatment and electric transformation of nickel‐containing wastewater. The Ni(OH)2/Ce(OH)4 hybrid nanosheets were prepared by Ce doping experiment, and Ni/Ce oxide was prepared by calcination with Ni(OH)2/Ce(OH)4 composite nanosheets. Finally, Ce(OH)4 was prepared by electroconversion with CeCl3 ⋅ 7H2O as raw material, and all the samples were used as CO2 photocatalysts for performance comparison. The diameter and thickness of Ni(OH)2/Ce(OH)4 and NiO/CeO2 nanocrystals are about 1∼50 nm and 1∼10 nm, respectively. The BET‐specific surface area is calculated to be 205.93 m2/g (Ni(OH)2/Ce(OH)4) and 18.93 m2/g (NiO/CeO2). During CO2 photoreduction, bare Ce(OH)4 can only produce CO (1.32 μmol after 4 h). The methane yield of Ni(OH)2/Ce(OH)4 is 11.435 μmol after 4 h, while the CO yield increases to 21.515 μmol after 4 h. Compared with the oxide NiO/CeO2, the electrolytic product Ni(OH)2/Ce(OH)4 showed a higher photocatalytic activity for CO2 reduction, which is attributed to the larger specific surface area of the precursor. We believe this work provides a potential approach for treating nickel‐containing electroplating wastewater to prepare highly efficient and selective CO2 reduction photocatalysts.