脱合金制备纳米多孔双金属氧化物NiMoO_4及其电化学性能

采用快速凝固与脱合金相结合的方法制备纳米多孔Ni-Mo合金,然后退火获得三维双连续纳米多孔NiMoO_4,采用XRD、SEM、TEM对多孔NiMoO_4的成分、形貌和结构进行表征,并通过循环伏安、恒电流充放电等方法测试多孔NiMoO_4电极的电化学性能。结果表明,Ni_5Mo_5Al_(90)和Ni_(2.5)Mo_(2.5)Al_(95)经脱合金和退火均可获得纳米多孔NiMoO_4,Mo元素对脱合金具有钉扎作用,可减小多孔合金的骨架和孔隙尺寸,由Ni_5Mo_5Al_(90)合金获得纳米多孔NiMoO_4表现出更为优异的超电容性能,其在1 A·g~(-1)电流密度比容量达708 F·g~(-1),当电流密度增加20 A·g~(-1),其比容保持率达57.1%。在4 A·g~(-1)电流密度下循环充放电1 000次,其比容保持率达91.2%。

Preparation and Electrochemical Performance of Nanoporous NiMoO4 by De-alloying

Nanoporous Ni-Mo alloy was prepared by a method of rapid quenching and de-alloying, and the samples were annealed to synthesize the nanoporous NiMoO₄ material. The composition, morphology and microstructure of NiMoO₄ were analyzed by XRD, SEM and TEM. The electrochemical performance was investigated by cyclic voltammetry and galvanostatic charge-discharge. The results show that the 3D bicontinuous nanoporous NiMoO₄ can be prepared by de-alloying and annealling of the Ni₅Mo₅Al₉₀ and Ni_2.5Mo_2.5Al₉₅ alloy. Molybdenum with a low surface diffusivity has a pinning effect on mobile Ni atoms, thus leading to the decrease of the skeleton and pore size. The specific capacitance of nanoporous NiMoO₄ prepared by Ni₅Mo₅Al₉₀ is 708 F·g^-1 at current density of 1 A·g^-1 and its retention ratio remains at 57.1% when the current density increases to 20 A·g^-1. After galvanostatic charge-discharge 1 000 cycles at 4 A·g^-1, the retention ratio of specific capacitance is 91.2%.