酸性环境中光电化学水分解具有广阔的应用前景,但由于缺乏稳定的光阳极以及有效的非贵金属助催化剂,其发展受到了极大的阻碍.WO_(3)是能够在酸性环境下稳定的半导体之一,但其在光照下的快速性能衰减仍然是一个悬而未决的问题.本研究提出...酸性环境中光电化学水分解具有广阔的应用前景,但由于缺乏稳定的光阳极以及有效的非贵金属助催化剂,其发展受到了极大的阻碍.WO_(3)是能够在酸性环境下稳定的半导体之一,但其在光照下的快速性能衰减仍然是一个悬而未决的问题.本研究提出WO_(3)和WO_(3)/SnO_(2)光阳极光电流的快速下降是因为电极/电解质界面上产生的羟基自由基(OH·)导致的.我们发现在pH为0.3的电解质中引入钴(Co^(2+))离子可以有效解决这个问题.Co^(2+)的存在可以促进H_(2)O高效氧化为O_(2),而不是产生不利的OH·自由基.最终在Co^(2+)存在条件下,可以将光电分解水的法拉第效率从40%提高到95%,将光电流密度从0.6提高到0.8 mA cm^(-2),并在1.2 V(可逆氢电极)下稳定25 h.重要的是,在利用维生素C淬灭OH·自由基以后,其光电流稳定性表现出与引入Co^(2+)离子时一致,进一步表明Co^(2+)离子对于OH·的关键抑制作用.此外,原位紫外-可见光谱和拉曼光谱表明Co^(2+)会捕获表面空穴并被氧化为Co^(3+).电子顺磁共振也进一步揭示了Co^(2+)离子对OH·自由基的抑制作用.本研究为均相的Co^(2+)/Co^(3+)氧化还原物种与光阳极结合用于强酸中的水氧化提供了参考.展开更多
The capability of fast charge and fast discharge is highly desirable for the electrode materials used in supercapacitors and lithium ion batteries.In this article,we report a simple strategy to considerably improve th...The capability of fast charge and fast discharge is highly desirable for the electrode materials used in supercapacitors and lithium ion batteries.In this article,we report a simple strategy to considerably improve the high rate capability of Co_(3)O_(4)nanowire array electrodes by uniformly loading Ag nanoparticles onto the surfaces of the Co_(3)O_(4)nanowires via the silver-mirror reaction.The highly electrically conductive silver nanoparticles function as a network for the facile transport of electrons between the current collectors(Ti substrates)and the Co_(3)O_(4)active materials.High capacity as well as remarkable rate capability has been achieved through this simple approach.Such novel Co_(3)O_(4)-Ag composite nanowire array electrodes have great potential for practical applications in pseudo-type supercapacitors as well as in lithium ion batteries.展开更多
基金supported by the National Natural Science Foundation of China(22072013)。
文摘酸性环境中光电化学水分解具有广阔的应用前景,但由于缺乏稳定的光阳极以及有效的非贵金属助催化剂,其发展受到了极大的阻碍.WO_(3)是能够在酸性环境下稳定的半导体之一,但其在光照下的快速性能衰减仍然是一个悬而未决的问题.本研究提出WO_(3)和WO_(3)/SnO_(2)光阳极光电流的快速下降是因为电极/电解质界面上产生的羟基自由基(OH·)导致的.我们发现在pH为0.3的电解质中引入钴(Co^(2+))离子可以有效解决这个问题.Co^(2+)的存在可以促进H_(2)O高效氧化为O_(2),而不是产生不利的OH·自由基.最终在Co^(2+)存在条件下,可以将光电分解水的法拉第效率从40%提高到95%,将光电流密度从0.6提高到0.8 mA cm^(-2),并在1.2 V(可逆氢电极)下稳定25 h.重要的是,在利用维生素C淬灭OH·自由基以后,其光电流稳定性表现出与引入Co^(2+)离子时一致,进一步表明Co^(2+)离子对于OH·的关键抑制作用.此外,原位紫外-可见光谱和拉曼光谱表明Co^(2+)会捕获表面空穴并被氧化为Co^(3+).电子顺磁共振也进一步揭示了Co^(2+)离子对OH·自由基的抑制作用.本研究为均相的Co^(2+)/Co^(3+)氧化还原物种与光阳极结合用于强酸中的水氧化提供了参考.
基金This work was jointly supported by the City University of Hong Kong(Project 7002465)the National Natural Science Foundation of China(No.21001117/B0107).
文摘The capability of fast charge and fast discharge is highly desirable for the electrode materials used in supercapacitors and lithium ion batteries.In this article,we report a simple strategy to considerably improve the high rate capability of Co_(3)O_(4)nanowire array electrodes by uniformly loading Ag nanoparticles onto the surfaces of the Co_(3)O_(4)nanowires via the silver-mirror reaction.The highly electrically conductive silver nanoparticles function as a network for the facile transport of electrons between the current collectors(Ti substrates)and the Co_(3)O_(4)active materials.High capacity as well as remarkable rate capability has been achieved through this simple approach.Such novel Co_(3)O_(4)-Ag composite nanowire array electrodes have great potential for practical applications in pseudo-type supercapacitors as well as in lithium ion batteries.
