S-doped carbon aerogels/GO composites as oxygen reduction catalysts

Composites of carbon aerogel and graphite oxide（GO） were synthesized using a self-assembly method based on dispersive forces. Their surface was modified by treatment in hydrogen sulfide at 650 and800 ℃. The samples obtained were characterized by adsorption of nitrogen, TA-MS, XPS, potentiometric titration, and HRTEM and tested as catalysts for oxygen reduction reactions（ORR） in an alkaline medium.The synergistic effect of the composite（electrical conductivity, porosity and surface chemistry） leads to a good ORR catalytic activity. The onset potential for the composite of carbon aerogel heated at 800 ℃ is shifted to a more positive value and the number of electron transfer was 2e-at the potential 0.68 V versus RHE and it increased to 4e-with an increase in the negative values of the potential. An excellent tolerance to methanol crossover was also recorded.

A novel composite(FMC)to serve as a durable 3D-clam-shaped bifunctional cathode catalyst for both primary and rechargeable zinc-air batteries

Novel and highly durable air cathode electrocatalyst with three dimensional （3D）-clam-shaped structure, MnO2 nanotubes-supported Fe2O3 （Fe2O3/MnO2） composited by carbon nanotubes （CNTs） （（Fe2O3/ MnO2）3/4-（CNTs）1/4） is synthesized using a facile hydrothermal process and a following direct heat- treatment in the air. The morphology and composition of this catalyst are analyzed using scanning elec- tronic microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and energy dispersive X-ray spectroscopy （EDX）. The morphology characteristics reveal that flower-like Fe2O3 parti- cles are highly dispersed on both MnO2 nanotubes and CNT surfaces, coupling all three components firmly. Electrochemical measurements indicate that the synergy of catalyst exhibit superior bi- functional catalytic activity for both oxygen reduction reaction （ORR） and oxygen evolution reaction （OER） as well as stability than Pt/C and lrO2 catalysts. Using these catalysts for air-cathodes, both primary and rechargeable zinc-air batteries （ZABs） are assembled for performance validation. In a primary ZAB, this 3D-clamed catalyst shows a decent open circuit voltage （OCV, -1.48 V） and a high discharge peak power density （349 mW cm 2）, corresponding to a coulomhic efficiency of 92%. In a rechargeahle ZABs with this bifunctional catalyst, high OCV （〉1.3 V） and small charge-discharge voltage gap （〈1.1 V） are achieved along with high specific capacity （780 mAh g 1 at 30 mA cm-2） and robust cycle-life （1,390 cycles at cycle profile of 20 mA/10 min）.