Preparation And Characterization Of Hierarchical Micro/nano-structures On Directional Porous Copper Substrate

Porous copper based Cu O or Cu（OH）₂nano-composites have important potential applications in catalytic,sensing,battery and other fields.The directional porous copper（DPC）substrate can promote the solute exchange due to the channel effect,thereby improving the performance of the loaded Cu O or Cu（OH）₂.Therefore,the preparation and characterization of Cu O and Cu（OH）₂micro-/nano-composite structures based on DPC substrates are of great significance.In this paper,DPC was successfully prepared by laser melting deposition（LMD）technique in combination with chemical corrosion.The Cu O nanowire structure and Cu（OH）₂nanograss structure were successfully prepared on the DPC by the thermal oxidation method and alkaline oxidation method to form Cu O/DPC and Cu（OH）₂/DPC hierarchical micro/nano-structures,respectively.The morphology evolution,growth mechanism and electrochemical glucose sensing performance of the two hierarchical micro/nano-structures were systematically studied.The main research results are as follows:The Cu₃₅Fe₆₅single-walled sample was prepared by LMD technique.Obvious phase separation phenomenon was observed.Directional Fe-rich non-developed dendrites were found in the Cu-rich substrate.After 12 h etching by a sulfuric acid solution,HPC with nanoporous copper loaded was obtained.After further ultrasound treatment,DPC was obtained.The DPC have a（100）directional texture with a pore diameter of 8.7±0.9μm.The prepared DPC substrate was thermally oxidized in the air,and Cu O nanowires formed on the surface of the DPC to form a Cu O/DPC micro-/nano-composite structure.The Cu O nanowires exhibit a diameter of about 100 nm and length of about 2500 nm.The effects of the DPC morphology and thermal oxidation parameters on the growth of Cu O nanowires were systematically studied.It is found that the growth of Cu O nanowires were mainly dominated by stress.The concave surface of the porous copper base can promote the growth of Cu O nanowires due to the accumulated compressive stress.The length of the Cu O nanowires increases with the extension of thermal oxidation time,but the changes of the nanowire density are not obvious.The non-enzyme sensitive performance of the Cu O/DPC micro-/nano-composite structure was tested.The Cu O/DPC micro-/nano-composite structure exhibit a sensitivity of～1.36 m A·mm^-1·cm^-2,a wide range of 1 to 10 mm and a detection limit as low as 1μm.The prepared DPC substrate was alkaline oxidized at room temperature conditions.Cu（OH）₂nanograsses form on the surface of DPC to form Cu（OH）₂/DPC micro-/nano-composite structure.The density and length of nanograsses increase with the extending alkaline oxidation time.The optimum density is obtained when the reaction time reaches 10 min,at which time the Cu（OH）₂nanograsses have a diameter of about 70 to 100nm,and the length is as long as 5μm.As the reaction time is further extended,Cu（OH）₂nanograsses gradually transforme into more stable Cu O nanosheets due to the dissolving and reconstruction transition.The preliminary glucose sensing performance test was performed on the prepared Cu（OH）₂/DPC micro-/nano-composite structure.A sensitivity of～2.204m A·cm^-2·mm^-1,a linear detection range of 9 mm,a detection limit of 0.05μm,and a response time of 4.8 s were obtained.The Cu（OH）₂/DPC micro-/nano-composite structure exhibits more excellent comprehensive performance in the common concentration range of human blood glucose.