CeO 2 nanotubes with well-defined hollow interiors are employed as support material for Pd electrocatalysts towards formic acid oxidation (FAO). Pd nanoparticles are deposited both on the outer surfaces and inside interiors of CeO 2 nanotubes. The as-prepared Pd catalysts possess a large electrochemical surface area (ESA) and exhibit improved electrocatalytic performance towards FAO in comparison with the Vulcan XC-72 carbon black and the commercial CeO 2 powder supported Pd catalysts.
Yun Zhu,Zezhou Yang,Lifei Song,Maoqiang Chi,Meixuan Li,Ce Wang,Xiaofeng Lu
A quick and sensitive detection of ascorbic acid (AA) is essential in the fields of biosensing and disease diagnosis. In this work, an effective approach combined with electrospinning, chemical bath deposition, and calcination process is developed to encapsulate Co 3 O 4 nanoparticle into CeO 2 nanotubes as efficient peroxidase mimics for the detection of AA. The peroxidase-like catalytic activity of the as-prepared Co 3 O 4 @CeO 2 nanotubes is much higher than that of individual Co 3 O 4 nanofibers and CeO 2 nanotubes alone due to the synergistic effect between the two components. Owing to the superior catalytic efficiency of the prepared Co 3 O 4 @CeO 2 nanotubes, a colorimetric route for the rapid and accurate detection of AA with a detection limit of 0.73 × 10 −9 m with a wide linear range from 0 to 0.8 × 10 −6 m is demonstrated. This detection limit is much better than the previous reports based on the enzyme-like catalytic systems. In addition, a good selectivity toward the detection of AA over amino acids, common ions, dopamine, and uric acid is achieved. This study offers a new approach for the fabrication of Co 3 O 4 @CeO 2 nanotubes as sensing platform toward the detection of AA, which presents promising potential applications in biosensing, environmental monitoring, and medical diagnostics.
In this work, we proposed a new hybrid of Pd nanoparticles dispersed on CeO 2 nanotubes (Pd NPs/CeO 2 NTs) with synergistically enhanced peroxidase-like activity for the visual detection of sulfhydryl compounds. In comparison with individual Pd NPs and CeO 2 NTs, the Pd NPs/CeO 2 NTs hybrid exhibited a synergy effect to trigger the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to its blue product TMBox mediated by H 2 O 2 . It was further demonstrated that the improved activity observed in Pd NPs/CeO 2 NTs originated from the strong interplays between Pd NPs and CeO 2 NTs, which could significantly increase the Ce 3+ /Ce 4+ ratio. Besides, sulfhydryl compounds were found to have the capacity to suppress the color reaction of TMB + H 2 O 2 catalyzed by the Pd NPs/CeO 2 NTs nanozyme at a low level. Based on this principle, mercaptoacetic acid in the concentration range of 66–400 nM could be linearly determined. Similarly, sulfhydryl-containing amino acid (cysteine) and its derivative (glutathione) in the linear scope of 6–40 nM were also detected, providing a detection limit down to 2.9 and 11.3 nM, respectively.
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