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Abstract Na-superionic conductor-structured Na 3 V 2 (PO 4) 3 is extensively investigated as a promising cathode material for sodium-ion batteries. Unfortunately, the Na 3 V 2 (PO 4) 3 cathode suffers from low rate capability due to its inherent low electric conductivity. One of the general solutions to this dilemma is to embed the Na 3 V 2 (PO 4) 3 nanoparticles uniformly within carbon matrix, however, the effect of carbon matrix categories on the sodium storage performance of Na 3 V 2 (PO 4) 3 is unclear. Here we systematically compare the influence of different carbon matrix on the electrochemical properties of the Na 3 V 2 (PO 4) 3 cathode and find that expanded graphite outperforms carbon nanotubes and carbon black as carbon matrix. As a result, the as-synthesized Na 3 V 2 (PO 4) 3 /expanded graphite composite delivers a high reversible capacity of 111.4 mAh g−1 at 1C, superior rate capability (105 mAh g−1 at 50C), and ultralong cycle life (48 mAh g−1 after 20,000 cycles at 50C), which are better than most Na 3 V 2 (PO 4) 3 -based composites reported previously. Moreover, the remarkable electrochemical performance of Na 3 V 2 (PO 4) 3 /expanded graphite in symmetric cells further advances the practical application of sodium-ion batteries. Graphical abstract Image 1 Highlights • NVP/C composites are synthesized by freeze drying, ball milling, and annealing. • A systematic study of the influence of different carbon matrix are carried out. • Excellent rate capability and ultralong cycle life are demonstrated by NVP/EG. • Superior electrochemical properties of NVP/EG in symmetric cells are revealed. [ABSTRACT FROM AUTHOR]

Herein, we develop a new kind of carbon supported gold-phosphorus (Au-P/C) electrocatalyst for the alkaline ethanol oxidation reaction (EOR). The Au-P/C catalysts with different Au/P ratio (i.e., AuP/C, Au 3 P 2 /C and Au 4 P 3 /C) can be obtained by a facile and novel hot-reflux method with white phosphorus (P 4 ) as reductant and ethanol as solvent. The crystal structure, composition and particle-size of the Au-P/C catalysts are investigated by X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), etc. The results demonstrate that Au-P/C catalysts present an alloy phase with the high content of P, ultrafine particle-size and high dispersity on carbon support, which results in excellent electrocatalytic activity and stability towards the EOR compared with that of the free-phosphorus Au/C catalyst. In addition, among the various Au-P/C catalysts with different Au/P ratio, the AuP/C sample exhibits the best electrocatalytic performance in comparison with other Au 3 P 2 /C and Au 4 P 3 /C samples. [ABSTRACT FROM AUTHOR]

The direct electron transfer and electrocatalysis of hemoglobin (Hb) immobilized on the phosphonate functionalized multi-walled carbon nanotubes (MWCNTs) are investigated. Fourier transform infrared (FT-IR) spectra, UV–vis spectra and cyclic voltammetry (CV) analyses reveal that the phosphonate functionalized MWCNTs have good biocompatibility for Hb immobilization, and promote the electron communication between Hb and electrode. The immobilized Hb shows a pair of redox peak with a formal potential of −406±10mV (vs. SCE) and the electrochemical behavior of Hb was a surface-controlled process in a pH 7.0 phosphate buffer solution. And the immobilized Hb can act in an electrocatalytic manner in the electrochemical reduction of nitric oxide (NO). Accordingly, an unmediated NO electrochemical biosensor is constructed. Under optimized experimental conditions, the NO electrochemical biosensor shows the fast response (less than 3s), the wide linear range (1.5×10−7 to 2.7×10−4 M) and the low detection limit (1.5×10−8 M), which is attributed to the good mass transport, the large Hb loading per unit area and the fast electron transfer rate of Hb. [ABSTRACT FROM AUTHOR]