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Both Al and Ga have exhibited excellent performance, respectively, for the An/Ln separation based on molten salt electrolysis, and the Al-Ga composite cathode may have superior properties. Therefore, in this work, the electrochemical behaviors of Ce (III) on the binary Al-Ga electrode were systematically explored by co-reduction of Ce (III), Al (III) and Ga (III) on a W electrode. A new oxidation signal of Al 2 Ga 2 Ce ternary intermetallic compound was successfully detected. In addition, for comparison, the co-reduction behaviors of Ce (III) with Al (III) and Ce (III) with Ga (III) on an inert tungsten electrode were also investigated. The results showed that different kinds of alloys are formed on the surface of W electrode. Finally, several typical Ga-Ce and Al-Ga-Ce intermetallic compounds were obtained by potentiostatic electrolysis and the deposited products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). [ABSTRACT FROM AUTHOR]

Abstract Under over-increasing demand of advanced lithium-ion batteries (LIBs) for long-range electric vehicles (EVs), high-capacity transition metal oxide (TMO) negative electrodes for LIBs are thought as potential substitutes of traditional graphite anodes. A major barrier for TMO anodes is volumetric expansion during lithiation processes, leading to active material pulverization and falling off current collectors, which seriously deteriorates capacity retention. Herein, apart from conventional mechanical degradation, another capacity fading mechanism is revealed. Furthermore, the understanding is supported by an interesting cycling property. Firstly, NiCo 2 O 4 with designed morphologies of nanoplates and microspheres are studied for the initial (de)lithiation and prolonged cycles. The morphology changes indicate solid electrolyte interphase (SEI) layer accumulating on the surface of electrodes and impeding the contact and reactions between lithium and active materials with a result of severe capacity loss. It can be understood as SEI layer insulating NiCo 2 O 4 , and if SEI film appropriately changes, high capacities can recovery. This conjecture is confirmed by following research of NiCo 2 O 4 nanoparticles with amazing cycling performance prepared by a facile water-bath method. As LIB anodes, NiCo 2 O 4 nanoparticles exhibit capacities of 1144 mAh g−1 at the initial discharging, 230 mAh g−1 at the 100th cycle and 661 mAh g−1 at the 500th cycle. The corresponding coulombic efficiency is of 73.1%, 98.4% and 99.5%, respectively. By TEM characterization in combination with electrochemical analysis, size-dependent SEI layer reactivation (from thick and unstable to thin and stable) is a key role on the dramatic capacity recovery. [ABSTRACT FROM AUTHOR]

Efficient nonprecious electrocatalysts with fast kinetics for the the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical to improve the efficiency of electrochemical systems such as fuel cells and metal-air battereies. Here, Co 9 S 8 embedded in porous nitrogen-doped carbon (N-C) matrix has been designed and fabricated. The as-fabricated Co 9 S 8 /N-C hybrid shows an excellent ORR activity, which is comparable to that of the commercial Pt/C (20 wt.%). Notably, the OER activity of Co 9 S 8 /N-C hybrid is superior to that of the RuO 2 /C (20 wt.%), a benchmark electrocatalyst for OER. The stabilities of Co 9 S 8 /N-C hybrid toward ORR and OER are significantly improved as compared to that of Pt/C (20 wt.%) and RuO 2 /C (20 wt.%), respectively. The synergistic effect of the covalent coupling between Co 9 S 8 and N-C and the porous structure of N-C is responsible for the enhanced catalytic activity and durability of Co 9 S 8 /N-C hybrid. [ABSTRACT FROM AUTHOR]

The spinel-type MnCo 2 O 4 is an attractive bifunctional electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, the catalytic activity of MnCo 2 O 4 is limited by its poor electronic conductivity. Herein MnCo 2 O 4 coated with conducting polypyrrole (i.e. MCO@PPyhybrid) is synthesized. The obtained MCO@PPy hybrid exhibits excellent electrocatalytic activity for both the ORR and OER, outperforming pristine MCO, PPy and MCO+PPy mixture. The ORR and OER activities of MCO@PPy are comparable to that of the commercial Pt/C (20 wt.%) and RuO 2 /C (20 wt.%), benchmark electrocatalysts for ORR and OER, respectively. While the stabilities of MCO@PPy hybrid toward both the ORR and OER are much higher than that of Pt/C (20 wt.%) and RuO 2 /C (20 wt.%), respectively. The PPy coating on the surface of MCO provides a conductive network for fast electron transfer and the coupling between the PPy layer and MCO promotes the transfer of electrons from PPy to MCO, benefiting the ORR and OER. The results reveal the effectiveness of surface modification with conducting polymer on improving the electrocatalytic activity of spinel oxide. [ABSTRACT FROM AUTHOR]