Preparation And Electrochemical Performance Of Nanoprous Binary Metal Oxides By Dealloying

Nanoporous materials have a very good prospect for application in Catalysis, sensor, fuel cells, biological medicine, microfluidics and micromechanics. Nanoporous materials have fascinating physical, chemical and mechanical properties because of thier great specific surface area, stable bicontinuous structure,mall size effect,surfa ce effect, macroscopic quantum tunnel effect and so on characteristics.The main objective in this research is to enhance electrochemical properties and stability of the transition metal oxides by porous and composite design.This research focuses on the dea lloying preparation of nanoprous binary metal oxides by different ternary alloy and their electrochemiacl properties.The Ni-Co-Al alloys of different composition make up of different phases synthesized by rapid quenching. Initial alloy phase impacts on pr ocess of dealloying.3.30and Ni_6.7Co_13.3Al₈₀ alloys which contain Al70Co15Ni15 quasicrystals cann't be dealloyed drastically. For Ni_3.3Co_6.7Al₉₀ and Ni_1.7Co_3.3Al₉₅ alloys which contain ?-Al and Al₉Co₂, bicontinuous schistose ligament structure with the thickness form 10 to 20 nm can be obtained after dealloying. Then the prepared samples were annealed at the temperature of 350 ? to gain the nanoporous Ni Co₂O₄ material.Their specific capacitances respectively are 755 F·g^-1 and 663 F·g^-1 at current density of 1 A·g^-1,and the specific capacitance can remain at 76.6% and 73.6% 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 are 93.9% and 95.5%. The good cycling stability benefits from the bicontinuous nanoprous structure of Ni Co₂O₄.Initial alloy composition and phase also impact on dealloying process of Ni-Mo-Al alloys.Ni₁₅Mo₁₅Al₇₀and Ni₁₀Mo₁₀Al₍800 alloys which contain Al_7.51Mo₍1.070Ni_1.42ternary phase cann't be dealloyed drastically. For Ni₅Mo₅Al₉₀ and Ni_2.5Mo_2.5Al₉₅ alloys which contain ?-Al and Al₃ Ni,bicontinuous nanoprous structure can be obtained after dealloying.In virtue of the pinning effect caused by these dopants Mo, the length scale of as-dealloyed nanoporous alloys can be significantly reduced.T hen the prep ared samples were annealed at the temperature of 600 ? to gain the nanoporous Ni MoO₄ material.Their specific capacitances respectively are 708 F ·g^-1 and 618 F·g^-1 at current density of 1 A·g^-1,and the specific capacitance can remain at 57.1% and 55.0% 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 are 91.2% and 90.7%, Shows good electrochemical properties and cycle stabilityInitial alloy Ni_3.3Co_6.7Mn₉₀ is Mn single-phase solid solution alloy, bicontinuou s ligament structure can be obtained after dealloying in NH₄Cl. T he pores are uniform and fine with the size of ligament between pores from 40 to 80 nm and the nanopore size from 30 to 50 nm.Then the prepared samples were annealed at the temperature of 350 ? to gain the nanoporous Ni Co₂O₄ material.The specific capacitance of nanoporous Ni Co₂O₄ is 674 F·g^-1 at current density of 1 A·g^-1 and the specific capacitance can remain at 72.0% when the cu rrent 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 92.9%.