CeO2/Cr2O3 direct Z-scheme heterojunction for photo-thermal synergistic catalytic isopropanol degradation and nitrogen fixation

Abstract

A CeO₂/Cr₂O₃ composite heterojunction material is prepared by the combination of a water bath method and a high temperature calcination method. The CeO₂/Cr₂O₃ composite shows enhanced photo-thermal synergistic catalytic activity in comparison with single component Cr₂O₃ and CeO₂. The photo-thermal catalytic nitrogen fixation rate of the CeO₂/Cr₂O₃ composite is 21.0 times that of Cr₂O₃ and 11.7 times that of CeO₂. The photo-thermal catalytic isopropanol degradation rate of the CeO₂/Cr₂O₃ composite is 1.3 times that of Cr₂O₃ and 3.0 times that of CeO₂. The improved catalytic activity of the CeO₂/Cr₂O₃ composite is attributed to the following three points. The CeO₂/Cr₂O₃ heterojunction exhibits a Z-scheme charge transfer mechanism, and the photo-generated carriers have a strong redox ability. There are abundant oxygen vacancies in the CeO₂/Cr₂O₃ composite, which can form a new impurity level leading to the weakening of carrier recombination. The CeO₂/Cr₂O₃ composite has a large specific surface area, which can provide more catalytically reactive sites. Moreover, the photo-thermal catalytic isopropanol degradation activity of CeO₂/Cr₂O₃ has no significant decrease after four cycle experiments, proving its good stability. This study inspires the design and construction of efficient photo-thermal catalysts in the field of air purification and energy conversion.