RESUMO
A novel Bi13S18I2 structure was synthesized using a facile one-pot hydrothermal method and further optimized as an anode material using graphene. The graphene/Bi13S18I2 composite achieved a high discharge capacity with an initial value of 1126.5 mA h g-1 and a high and stable discharge capacity of 287.1 mA h g-1 after 500 cycles compared with pure Bi13S18I2, which derives from the inhibited volume expansion and high electrical conductivity obtained from graphene. In situ XRD was performed to analyze the Li storage mechanism in depth. The results support the feasibility of the new ternary sulfide Bi13S18I2 as a promising lithium ion battery.
RESUMO
A ternary mixed metal oxide coating of Sn-Ru-CoO x was prepared by ultrasonic treatment. The effect of ultrasound on the electrochemical performance and corrosion resistance of the electrode was investigated in this paper. Results showed that the electrode prepared by ultrasonic pretreatment demonstrated more uniform oxide dispersion on the surface of the coating, smaller grain growth, and more compact surface morphology compared with the anode prepared without ultrasonic pretreatment. At the same time, the best electrocatalytic performance was obtained by the ultrasonically treated coating. The chlorine evolution potential was reduced by 15 mV. The anode prepared by ultrasonic pretreatment had a service life of 160 h, which was 46 h longer than the anode prepared without ultrasonic pretreatment.
RESUMO
The oxygen evolution reaction kinetics in industrial zinc electrowinning is sluggish, resulting in low electrocatalytic activity and substantial energy expenditure (about one-third of energy was wasted due to the strong polarization effect). Herein, the paper described a core-shell structured MnCo2O4.5@C modified PbO2 electrode through the pyrolysis and co-electrodeposition as a promising candidate for zinc electrowinning. As a result, the obtained Pb-0.2%Ag/α-PbO2/ß-PbO2-MnCo2O4.5@C composite electrode showed a sandwich-like structure, where Pb-0.2%Ag as a core, α-PbO2 as a mid-layer, and ß-PbO2-MnCo2O4.5@C served as an electrocatalytic layer. It also possessed improved OER catalytic activity, only required 680 mV to achieve a current density of 50 mA cm-2 and a Tafel slope of 216.04 mV dec-1 in an acidic solution containing 50 g L-1 Zn2+ and 150 g L-1 H2SO4. The current efficiency increased by 0.7% and the cell voltage reduced by 360 mV as compared to a conventional Pb-0.76%Ag alloy electrode, leading to a remarkable energy-consumption reduction of 283.5 kW h for producing per ton metallic zinc. Furthermore, Pb-0.2%Ag/α-PbO2/ß-PbO2-MnCo2O4.5@C exhibited a prolonged service life, which worked about 44 h under an ultra-high current density of 2 A cm-2. Hence, this paper provides the strategy to design and construct non-precious, high-performance catalyst for electrolysis and other applications.
RESUMO
MnO2 coatings prepared in a sulfate system (S-MnO2) and MnO2 prepared in a nitrate system (N-MnO2) were successfully deposited on porous Ti/Sn-Sb-RuO x /ß-PbO2 substrates by electrodeposition, and their electrochemical properties were studied in detail. The bath composition plays a very important role in the MnO2 coating prepared by electrodeposition at a low current density. The results of scanning electron microscopy show that a Ti/Sn-Sb-RuO x /ß-PbO2/MnO2 electrode has a rough morphology and the unit cell is very good. At the same time, the surface cracks in the S-MnO2 coating are larger than those in the N-MnO2 coating. In addition, the N-MnO2 coating is composed of a fluffy sheet-like substance. The surface morphology of the N-MnO2 coating is denser than that of the S-MnO2 coating. The S-MnO2 coating consists of irregularly stacked granular particles. Further, the main crystal phase of MnO2 is γ type, and the main valence state of MnO2 is +4. The results show that the oxygen evolution potential of the N-MnO2 electrode is 63 mV lower than that of the S-MnO2 electrode, indicating that the N-MnO2 electrode has better oxygen evolution activity and electrochemical stability, which can also be confirmed by EIS test results. Under the accelerated life test conditions, the N-MnO2 electrode has a better service life of 77 h at a current density of 1 A cm-2 in 150 g L-1 H2SO4 and 2 g L-1 Cl- solution.
RESUMO
The high energy consumption during zinc electrowinning is mainly caused by the high overpotential of the oxygen evolution for Pb-Ag alloys with strong polarization. The preparation of new active energy-saving materials has become a very active research field, depending on the synergistic effects of active particles and active oxides. In this research, a composite material, α(ß)-PbO2, doped with Co3O4 and CNTs on the porous Ti substrate was prepared via one-step electrochemical deposition and the corresponding electrochemical performance was investigated in simulated zinc electrowinning solution. The composite material showed a porous structure, finer grain size and larger electrochemical surface area (ECSA), which indicated excellent electrocatalytic activity. Compared with the Pb-0.76 wt% Ag alloy, the overpotential of oxygen evolution for the 3D-Ti/PbO2/Co3O4-CNTs composite material was decreased by about 452 mV under the current density of 500 A m-2 in the simulated zinc electrowinning solution. The decrease in the overpotential of oxygen evolution was mainly ascribed to the higher ECSA and lower charger transfer resistance. Moreover, it showed the lowest self-corrosion current density of 1.156 × 10-4 A cm-2 and may be an ideal material for use in zinc electrowinning.
