Jiasheng Xu

Research on the self-assembly of exfoliated perovskite nanosheets (LaNb2O7−) and cobalt porphyrin utilized for the electrocatalytic oxidation of ascorbic acid

A sandwich-structured nanocomposite of LaNb2O7/CoTMPyP [5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrinato cobalt(III)] was fabricated via electrostatic interaction between a LaNb2O7− colloidal dispersion and a cobalt porphyrin aqueous solution. Several analytic techniques such as X-ray diffraction (XRD), Fourier transform infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and scanning electron microscopy (SEM) were used to characterize the obtained products and the existence of LaNb2O7− nanosheets was confirmed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Furthermore, the stable and well-dispersed colloidal suspension of the LaNb2O7− nanosheets, whose zeta potential value was −51.9 mV, was monitored with a Zetasizer Nano instrument. On the other hand, the cyclic voltammetry measurements of the LaNb2O7/CoTMPyP film modified GCE exhibited excellent electrocatalytic activities toward ascorbic acid oxidation with the oxidation peak potential shifting from 0.380 V (bare glass carbon electrode) to 0.044 V (modified electrode). The oxidation peak current increased linearly with the square root of the scan rate, implying a diffusion-controlled process. In addition, a detection limit of 4.99 × 10−5 M was obtained through differential pulse voltammetry with results in a concentration range of 5 × 10−5 to 9.09 × 10−3 M at a signal-to-noise ratio of 3.0.

Electrostatic self-assembly of exfoliated niobate nanosheets (Nb3O8−) and cobalt porphyrins (CoIIITMPyP) utilized for rapid construction of intercalated nanocomposite and exploration of electrocatalysis towards oxygen reduction

To prepare the novel plate-like nanocomposite CoIIITMPyP/Nb3O8, the cationic cobalt (III) tetrakis–5, 10, 15, 20–(N–methyl–4–pyridyl) porphyrin (CoIIITMPyP) was intercalated into the interlayer of the perovskite structural material KNb3O8 via the electrostatic self-assembly of the positively charged CoIIITMPyP molecules and the electronegative Nb3O8− nanosheets. The Nb3O8− nanosheets was obtained by exfoliating the protonated product of niobate KNb3O8 in the tetrabutyl ammonium hydroxide (TBA+OH−) aqueous solution. The zeta potential was measured to indicate the stability and uniformity of the Nb3O8− nanosheet colloidal dispersion, and the structure and component of the parent material KNb3O8, the acidified product HNb3O8, and the interlayered nanocomposite CoIIITMPyP/Nb3O8 were characterized using XRD, FT-IR, SEM and AFM. Furthermore, the electrocatalytic activity toward the oxygen reduction reaction (ORR) of CoIIITMPyP/Nb3O8 hybrids modified GCE was investigated by the cyclic voltammetry (CV) measuremen...