2.1 Materials
The porous Ti membrane substrate (wafer with diameter 20 mm, thickness 1 mm, pore size 10 μm, and porosity 45%) was purchased from Kunshan Yinghuixiong electronic technology company; 3-aminopropyltriethoxysilane (C9H23NO3Si) was purchased from Macklin Biochemical company; 2-methylimidazole (2-mIm) was purchased from Aladdin (Shanghai); Methanol was purchased from Knowles; Zinc nitrate hexahydrate, copper nitrate trihydrate, ethanol, sodium hydroxide and acetone were all purchased from Chengdu Kelong company. All materials are analytical grade and were used as received without further purification.