Chromium-phosphorus (Cr-P) coatings are electrodeposited from trivalent Cr (Cr(III)) baths containing hypophosphite. The electrochemical corrosion behavior of Cr-P coatings, traditional Cr coatings deposited in hexavalent Cr (Cr(VI)) baths, and chromium-carbon (Cr-C) coatings deposited in Cr(III) baths containing formate are studied by measuring potentiodynamic polarization curves in a 10 wt% HCl solution. The composition and morphology of the coating surface layers are investigated by X-ray photoelectron spectrometry (XPS) and scanning electron microscopy (SEM), respectively. The results of electrochemical tests show that Cr-P coatings exhibit better corrosion resistance than traditional Cr and Cr-C coatings, which is characterized by a lower critical current density, lower passive current density, and lager passive potential range. XPS and SEM analyses confirm that the excellent corrosion resistance of Cr-P coatings is attributed to the formation of a phosphide passive film, which has high stability and self-repairing ability, and can act as a “buffer” to reject the penetration of chloride ions. 相似文献
The Na1+xAlxTi2?x(PO4)3/C (x?=?0, 0.05, 0.10, 0.20) composites serving as anode for aqueous sodium ion battery are successfully synthesized through a facile sol–gel route. The results indicate that introduction of proper amount of aluminum has no obvious effect on the structure and morphology of NaTi2(PO4)3/C. Among the four synthesized samples, Na1.1Al0.1Ti1.9(PO4)3/C (NATP-0.10) exhibits the best electrochemical performance. NATP-0.10 delivers a discharge specific capacity of 115.8, 106.9, 98.4, and 89.1 mAh g?1 at 2, 5, 10, and 20 C rate, respectively, and still retains 114.7 mAh g?1 when the current density comes back to 2 C. Additionally, NATP-0.10 exhibits an initial discharge capacity of 102.9 mAh g?1 and still retains a reversible capacity of 90.1 mAh g?1 at 10 C rate after 200 cycles. Cyclic voltammetry and electrochemical impedance spectroscopy demonstrate the better electrochemical performance of NATP-0.10 is due to the faster sodium migration and enhanced electrochemical kinetics.
Graphical abstract
Al doping Na1+xAlxTi2?x(PO4)3/C (x?=?0, 0.05, 0.10, 0.20) composites were firstly used as anodes in aqueous SIBs. The electrochemical performance of NaTi2(PO4)3/C has been improved by introducing a proper amount of Al.
