Co 3 O 4 nanochain and Co 3 O 4 /CeO 2 heterostructures were prepared via an electrospinning process and subsequent calcination . The formation and shape evolution from Co 3 O 4 nanochains to Co 3 O 4 /CeO 2 composite nanobelts were investigated, suggesting that both components and preparation parameters play important roles in resulted morphology and properties. Homogeneous Co 3 O 4 /CeO 2 junctions in belt samples were formed towards enhanced catalysis performance. Well-dispersed Au nanoparticles were deposited on Co 3 O 4 /CeO 2 composite nanostructures or doped inside through reduction and direct calcination route method, respectively. The loading of Au nanoparticles significantly enhanced catalytic performance with onset CO conversion at 100 °C and resulted in CO conversion over at 127 °C.
Chaonan Jiao,Ying Zhu,Tongkai Ji,Xingwei Cai,Jing Wang
For yolk-shell structured nanoreactors , multiple active components can be precisely positioned on core and/or shell that can afford more exposed accessible active sites, and the internal voids can guarantee sufficient contact of reactants and catalysts. In this work, a unique yolk–shell structured nanoreactor [email protected] 3 O 4 /CeO 2 @mSiO 2 was fabricated and applied as nanozyme for biosensing. The [email protected] 3 O 4 /CeO 2 @mSiO 2 exhibited superior peroxidase-like activity with a lower Michaelis constant ( K m ) and a higher affinity to H 2 O 2 . The enhanced peroxidase-like activity was attributed to the unique structure and the synergistic effects between the multiple active components. Colorimetric essays were developed based on [email protected] 3 O 4 /CeO 2 @mSiO 2 for the ultra-sensitive sensing of glucose in the range of 3.9 nM–1.03 mM with the limit of detection as low as 3.2 nM. In the detection of glucose-6-phosphate dehydrogenase (G6PD), the cooperation between G6PD and [email protected] 3 O 4 /CeO 2 @mSiO 2 triggered the redox cycling between NAD + and NADH, thereby achieving the amplification of the signal and enhancing the sensitivity of the assay. The assay showed superior performance as compared to other methods with linear response of 5.0 × 10 −3 –15 mU mL −1 and lower detection limit of 3.6 × 10 −3 mU mL −1 . The fabricated novel multi-enzyme catalytical cascade reaction system allowed rapid and sensitive biodetection, demonstrating its potential in biosensors and biomedical applications.
Multicomponent heterogeneous structures of yolk@shell nanospheres embedded in MOF-derived porous carbon are potentially excellent electrocatalytic materials. In this work, the multicomponent yolk@shell nanospheres (Au@Co 3 O 4 @CeO 2 ) were synthesized through an autocatalytic redox reaction. The synergistic and interfacial effects between Co 3 O 4 and CeO 2 can expose more active sites and enhance the catalytic activity. Then, the electrical conductivity of Au@Co 3 O 4 @CeO 2 was improved using N-doped carbon nanomaterials (NPC), which was derived from ZIF-8 by high-temperature pyrolysis. The synergistic catalytic effect between ZIF-8 derived NPC and Au@Co 3 O 4 @CeO 2 resulted in the highest electrochemical response current to caffeic acid in this composite. Under optimal conditions, the prepared modified electrode showed a LOD (limit of detection) of 5.7 × 10 −10 M for CA and a linear range of 1.0 × 10 −9 to 3.0 × 10 −6 M. Meanwhile, it showed remarkable selectivity for CA in the anti-interference experiments and can be applied to the detection in food samples (strawberry and red wine). This work has developed a novel sensing material for sensitive detection of CA, broadening the application of multi-component shell-core structured metal oxidation.
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