Improved photocatalytic activity of LaFeO3 with doping Mn3+ ions and modifying Pd2+ ions for photoreduction of CO2 into CH4

Abstract

A new type of Mn-doped and Pd-modified LaFeO 3 (LaFeO 3 -Mn-Pd) photocatalyst is introduced by a sol-gel method. The existing states of dopants (Mn and Pd), the band structures, and the behaviors of photogenerated carriers for LaFeO 3 -Mn-Pd are studied. It is revealed that the Mn 3+ ions are doped into the LaFeO 3 lattice by substituting Fe 3+ ions, while the Pd 2+ ions exist as -O-Pd-Cl species on the surface of LaFeO 3 . The Mn 3+ ions and -O-Pd-Cl species increase the absorption of light. Moreover, a more suitable band structure for the redox potential of CO 2 conversion into CO and CH 4 , and higher carrier separation efficiency appeared. The Mn 3+ ions promote the conversion of CO 2 into CO for LaFeO 3 -Mn, while the -O-Pd-Cl surface species boost the conversion of CO into CH 4 for LaFeO 3 -Pd. Furthermore, the synergistic effect of Mn 3+ ions and -O-Pd-Cl species realize the conversion of CO 2 into CH 4 and improve the photocatalytic activity of LaFeO 3 -Mn-Pd effectively. These results offer a paradigm for the design and fabrication of novel LaFeO 3 -based photocatalysts with excellent photocatalytic performance. • The introduced Mn 3+ are doped into the LaFeO 3 in mode of substituting Fe 3+ . • The introduced Pd 2+ form –O–Pd–Cl species on the surface of LaFeO 3 . • The Mn-doped and Pd-modified on LaFeO 3 can improve the visible light absorption. • The Mn-doped and Pd-modified on LaFeO 3 can promote separation of carriers. • The synergistic effect of Mn 3+ and Pd 2+ ions can improve photocatalytic activity.