Hexagonal CePO 4 nanorods were prepared by a precipitation method and hexagonal CePO 4 nanowires were prepared by hydrothermal synthesis at 150 °C. Rh (NO 3 ) 3 was then used as a precursor for the impregnation of Rh 2 O 3 onto these CePO 4 materials. The Rh 2 O 3 supported on the CePO 4 nanowires was much more active for the catalytic decomposition of N 2 O than the Rh 2 O 3 supported on CePO 4 nanorods. The stability of both catalysts as a function of time on stream was studied and the influence of the co-feed (CO 2 , O 2 , H 2 O or O 2 /H 2 O) on the N 2 O decomposition was also investigated. The samples were characterized by N 2 adsorption-desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, hydrogen temperature-programmed reduction, oxygen temperature-programmed desorption, and CO 2 temperature-programmed desorption in order to correlate the physicochemical and catalytic properties.
LaPO 4 has been used as a support to make supported catalysts in some investigations, but the effect of different LaPO 4 supports on the catalytic performance of supported catalysts has been rarely reported. In this work, conventional hexagonal LaPO 4 (LaPO 4 H) was prepared by precipitation, and hexagonal LaPO 4 nanowires (LaPO 4 HNW) was prepared by hydrothermal synthesis at 150 °C. Monoclinic LaPO 4 nanowires (LaPO 4 -MNW-220 and LaPO 4 -MNW-900) were prepared by hydrothermal synthesis at 220 °C or calcining LaPO 4 HNW at 900 °C. These samples were used to support Rh 2 O 3 via impregnation using Rh(NO 3 ) 3 as a precursor. The activities of these supported catalysts in N 2 O decomposition and CO oxidation follow the same sequence of Rh 2 O 3 / LaPO 4 HNW > Rh 2 O 3 / LaPO 4 H > Rh 2 O 3 / LaPO 4 -MNW-220 > Rh 2 O 3 / LaPO 4 -MNW-900, i.e. , two hexagonal LaPO 4 supports are better than two monoclinic LaPO 4 supports in making active catalysts, and hexagonal LaPO 4 nanowires are better than hexagonal LaPO 4 composed of nanoparticles and short nanorods. The most active catalyst has highly dispersed Rh 2 O 3 species interacting strongly with the support, more oxygen-adsorption capacity, and more basic sites.
Jin Gao,Junxia Shao,Hua Li,Najun Li,Dongyun Chen,Qingfeng Xu,Jianmei Lu
The sluggish charge transfer and fast recombination of charge carriers is a determining factor limiting photocatalytic efficiency of carbon nitride. Herein, carbon vacancies and Rh 2 O 3 nanoparticles were sequentially introduced into CN to accelerate photo-generated electron and hole transfer simultaneously, thereby improving the photocatalytic performance of CN to achieve the complete removal of Bisphenol A (BPA) in 15 min. Mechanism analyses reveal that the modification of the carbon vacancies regulates the active charge carriers, excitons and trap states, thus enhances the carrier separation capabilities and light absorption. Meanwhile, the in situ photodeposited Rh 2 O 3 nanoparticles, as a hole-transfer mediator, maximally suppress recombination of photogenerated charges. These synergistic effects result in promoting the separation and transfer of charge carriers and thus improving photocatalytic performances. This strategy can serve as guideline for the reasonable design of efficient photocatalysts for phenolic wastewater remediation.
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