热电池正极材料钒氧碳的性能研究

对热电池正极材料钒氧碳(VOC)的合成方法及性能特点作了评述。实验在不同工艺条件下的热反应制得不同成分的VOC材料,运用X射线衍射光谱法(XRD)和扫描电镜技术对所得产物进行了物相分析及形貌分析,并对其作为热电池正极材料的放电性能作了检测研究。实验结果表明:反应物配比、煅烧时间和温度对生成的VOC物相及性能都有重要的影响。粉末颗粒径向粒径小,比表面积较大的层片状及细棒状材料满足Li+快速扩散,使电池能够在较大电流密度下以较高的电压放电。对VOC材料进行放电性能测试发现,VOC能够提供较高的电压和平稳的放电平台,同时该化合物的重现性较好,容易加工成型,是一种较为理想的正极材料。

Zinc-doped g-C_3N_4/BiVO_4 as a Z-scheme photocatalyst system for water splitting under visible light

A two‐step photocatalytic water splitting system,termed a“Z‐scheme system”,was achieved using Zn‐doped g‐C3N4for H2evolution and BiVO4for O2evolution with Fe2+/Fe3+as a shuttle redox mediator.H2and O2were evaluated simultaneously when the doping amount of zinc was10%.Moreover,Zn‐doped(10%)g‐C3N4synthesized by an impregnation method showed superior active ability to form the Z‐scheme with BiVO4than by in‐situ synthesis.X‐ray diffraction,UV‐Vis spectroscopy,scanning electron microscopy,and X‐ray photoelectron spectroscopy were used to characterize the samples.It was determined that more Zn?N bonds could be formed on the surface of g‐C3N4by impregnation,which could facilitate charge transfer.

Boosting catalytic activities of carbon felt electrode towards redox reactions of vanadium ions by defect engineering

Vanadium redox flow batteries(VRFBs)are one of the most promising energy storage systems owing to their safety,efficiency,flexibility and scalability.However,the commercial viability of VRFBs is still hindered by the low electrochemical performance of the available carbon-based electrodes.Defect engineering is a powerful strategy to enhance the redox catalytic activity of carbon-based electrodes for VRFBs.In this paper,uniform carbon defects are introduced on the surfaces of carbon felt(CF)electrode by Ar plasma etching.Together with a higher specific surface area,the Ar plasma treated CF offers additional catalytic sites,allowing faster and more reversible oxidation/reduction reactions of vanadium ions.As a result,the VRFB using plasma treated electrode shows a power density of 1018.3 mW/cm^(2),an energy efficiency(EE)of 84.5%,and the EE remains stable over 1000 cycles.

Ultradurable fluorinated V_(2)AlC for peroxymonosulfate activation in organic pollutant degradation processes

Vanadium‐based catalysts are considered the most promising materials to replace cobalt‐based catalysts for the activation of peroxymonosulfate(PMS)to degrade organic pollutants.However,these traditional vanadium species easily leak out metal ions that can affect the environment,even though the of vanadium is much less than that of cobalt.Compared to other vanadium‐based cata‐lysts,e.g.,V_(2)O_(3),fluorinated V_(2)AlC shows a high and constant activity and reusability regarding PMS activation.Furthermore,it features extremely low ion leakage.Active oxygen species scavenging and electron spin resonance measurements reveal that the main reactive oxygen species was 1O_(2),which was induced by a two‐dimensional confinement effect.More importantly,for the real‐life application of tetracycline(TC)degradation,the introduction of fluorine changed the adsorption mode of TC over the catalyst,thereby changing the degradation path.The intermediate products were detected by liquid‐chromatography mass spectroscopy(LC‐MS),and a possible degradation path was proposed.The environmental impact test of the decomposition products showed that the toxicity of the degradation intermediates was greatly reduced.Therefore,the investigated ultradu‐rable catalyst material provides a basis for the practical application of advanced PMS oxidation technology.

Carbon nanotubes loaded with vanadium oxide for reduction NO with NH_3 at low temperature

The catalytic activity of carbon nanotubes-supported vanadium oxide(V_2O_5/CNTs) catalysts in the selective catalytic reduction(SCR) of NO with NH_3 at low temperatures(<250℃) was investigated.The effects of V_2O_5loading,reaction temperature,and presence of SO_2 on the SCR activity were evaluated.The results show that V_2O_5/CNTs catalysts exhibit high activity for NO reduction with NH_3 at low-temperatures.The catalysts also show very high stability in the presence of SO_2.More interestingly,their activities are significantly promoted instead of being poisoned by SO_2.The promoting effect of SO_2 is distinctly associated with V_2O_5 loading,particularly maximized at low V_2O_5 loading,which indicated the role of CNTs support in this effect.The promoting effect of SO_2 at low temperatures suggests that V_2O_5/CNTs catalysts are promising catalytic materials for low-temperature SCR reactions.