Caini Fan,Junjia Liu,Haiying Zhao,Ling Li,Min Liu,Jing Gao,Li Ma
PtPd nanoflowers (PtPd NFs) exhibit intrinsic peroxidase-like activity as nanozymes, but the nanozymes lack substrate specificity and have low catalytic activity. Herein, a molecularly imprinted nanogel on PtPd NFs was prepared by using 3,3′,5,5′-tetramethylbenzidine (TMB) as the template through the aqueous precipitation polymerization method. After the TMB was washed out, many substrate binding pockets were retained in the PtPd NFs. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) were employed to characterize the molecularly imprinted polymer (MIP) PtPd nanoflowers (T-MIP-PtPd NFs). The obtained T-MIP-PtPd NFs exhibited enhanced catalytic activity and specific recognition for TMB. Compared with PtPd NFs, T-MIP-PtPd NFs showed a linear range from 0.01–5000 μM and a detection limit of 0.005 μM toward the detection of H2O2. Glucose can also be sensitively detected through cascade reaction by the T-MIP-PtPd NFs and glucose oxidase. Therefore, molecular imprinting on nanozymes technology shows promising application in biocatalysis and sensing fields.
Yi Zhang,Guoqiang Shu,Zhongtao Shang,Kui Ma,Lei Song,Chao Wang,Chang-An Zhou,Hairong Yue
Platinum-based electrocatalysts usually exhibit limited and quickly vanished activity for the methanol oxidation reaction (MOR) due to active site occupation and surface intermediate poisoning, especially CO. The attendant synergistic effect of the alloy strategy is often executed to improve these flaws. Here, PtPd nanoflower alloys uniformly anchored on the carbon paper were successfully synthesized by electrodeposition to construct well-defined active sites, over which high MOR activity and tolerance were realized. The homogeneous alloy structure of PtPd nanoflowers was confirmed by TEM and XAFS. Impressively, the Pt1Pd1-N NFs/CP exhibited an excellent mass activity of 9.25 A mgPt+Pd–1 and specific activity of 13.2 mA cmECSA–2 of MOR in the alkaline electrolyte, and 87.8% of the initial activity was still retained after 500 cycles. In situ infrared spectroscopy revealed that Pt1Pd1-N NFs/CP ensured the complete oxidation of methanol following a CO-free path. The investigation of the electronic and coordination structure demonstrated that the Pt–Pd adjacent sites with a zero valence are the highly active center for MOR, and the synergistic effect between Pt and Pd greatly improved the MOR electrocatalytic performance. This work offers an effective strategy to precisely control the number and structure of decorating species for constructing alloy nanocatalysts to enhance the electroactivity toward MOR.
Li Ma,Liya Zhou,Ying He,Lihui Wang,Zhihong Huang,Yanjun Jiang,Jing Gao
Mesoporous bimetallic PtPd nanoflowers (MPtPdN) were synthesized by a surfactant-directing method. The MPtPdN was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and wide-angle X-ray diffraction (XRD). The use of MPtPdN as a platform for the indirect electrochemical detection of organophosphate pesticides (OPs) via enzymatic inhibition pathway was demonstrated. Due to the nanostructure of MPtPdN and the synergy effect of the noble metal nanoparticles, a novel and sensitive acetylcholinesterase (AChE) biosensor for OPs detections based on MPtPdN and enzyme inhibition was prepared. The inhibition of omethoate exhibited a linear relationship from 4.7×10 −11 to 4.7×10 −8 M with a detection limit of 1.7×10 −12 M (S/N=3). The proposed AChE biosensor was reliable and can be used to measure the concentration of omethoate in different spiked samples with high accuracy and satisfactory recovery. The preparation of biosensors based on the MPtPdN can be further extended to construct many other important enzyme biosensors.
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