Effects of electrochemical synthetic conditions on surface property and photocatalytic performance of copper and iron-mixed p-type oxide electrodes

Earth-abundant copper and iron-mixed oxide(CuO/CuFeO_2; CFO) film electrodes are synthesized using an electrochemical deposition(ED) technique at two different ED potentials(-0.36 and-0.66 V vs saturated calomel electrode(SCE); denoted as ED-1 and ED-2, respectively). Then, their surface morphologies are compared, and the photo(electro)catalytic activities for the reduction of Cr(VI) are examined in aqueous solutions at pH 7 under simulated sunlight(AM 1.5 G; 100 mW cm~(-2)). The degree of the electrical potential applied to the ED process significantly affects the thickness of the synthesized electrode film and the intensity ratio of the diffraction peaks of CuO(111) and CuFeO_2(012). A 200 μm thick ED-2 sample with a distinct stacking of CuO on CuFeO_2 exhibits a larger broadband absorption spectrum than the 50-μm thick ED-1 with less separate stacking. Furthermore, the ED-2 sample has a higher intensity ratio of the diffraction peaks of CuO(111) and CuFe02(012) than ED-1. As-synthesized ED-2 samples produce larger photocurrents, leading to faster Cr(VI) reduction on the surface under given potential bias(-0.5 V vs SCE)or bias-free conditions. The energy levels(i.e., flatband potential) for the two samples are almost the same(only 10 mV difference), presumably supposing that the enhanced photoactivity of the ED-2 sample for Cr(VI) reduction is due to the facilitated charge transfer. The time-resolved photoluminescence emission spectra analysis reveal that the lifetime(r) of the charge carriers in the ED-1 sample is 0.103 ns, which decreases to 0.0876 ns in the ED-2. The ED-2 sample synthesized at a high negative potential is expected to contribute greatly to the application of other solar-to-fuel energy conversion fields as a highly efficient electrode material.     

2012—2020年欧盟食品和饲料快速预警系统中饲料通报分析

自2010年开始,中国成为世界第一饲料生产大国。在全球化经济格局下中国饲料对外出口进一步增加。欧盟对饲料安全监管一直走在世界前列,从而高效地确保了饲料安全,进而保证食品安全。中国饲料虽对欧盟出口不多,但本文通过对2012~2020年欧盟食品和饲料快速预警系统中饲料通报进行分析,总结各国通报中的饲料类型、通报类型、通报基础、通报原因、采取措施、风险决策和分销状况等内容,从而对中国饲料监管和饲料生产企业对外出口具有一定的借签意义。