摘要
An efficient photocatalytic CO_(2) reduction has been reported in ZIF-67-derived-Co nanoparticles(NPs)encapsulated in nitrogen-doped carbon layers(N-C/Co).This work demonstrates that the pyrolysis temperature is crucial in tuning the grain size and components of metallic Co^(0) of N-C/Co composite catalysts,which optimizes their photocatalytic activities.Syntheses were conducted at 600,700,and 800℃ giving the N-C/Co-600,N-C/Co-700,and N-C/Co-800 samples,respectively.N-C layers can well wrap the Co NPs obtained at a low pyrolysis temperature(600℃)owing to their smaller grains than those of other samples.A high metallic Co^(0) content in the N-C/Co-600 sample can be attributed to the effective inhibition of surface oxidation.By contrast,the surface CoOx oxides in the N-C/Co-700 and N-C/Co-800 samples cover inside Co cores,inhibiting charge separation and transfer.As a result,the N-C/Co-600 sample yields the best photocatalytic activity.The carbon monoxide and hydrogen generation rates are as high as 1.62×10^(4) and 2.01×10^(4)μmol g^(−1)h^(−1),respectively.Additionally,the Co NPs make composite catalysts magnetic,enabling rapid and facile recovery of catalysts with the assistance of an external magnetic field.This work is expected to provide an instructive guideline for designing metal-organic framework-derived carbon/metal composite catalysts.
本文报道了由ZIF-67衍生而来的N掺杂C层包裹Co纳米颗粒(NC/Co)复合催化剂及其高效光催化CO_(2)还原性能.研究发现热解温度对N-C/Co复合催化剂的晶粒尺寸和金属性Co^(0)含量的调控具有关键作用,并在此基础上优化了催化剂的光催化活性.在较低热解温度(600℃)下获得的Co纳米颗粒尺寸较小,能够被N-C层良好保护,从而有效抑制表面氧化,使得N-C/Co-600样品中具有更高含量的金属性Co^(0).相反,NC/Co-700和N-C/Co-800样品中的表面氧化物CoO_(x)覆盖了内部Co核,不利于电荷分离和迁移.因此,N-C/Co-600样品表现出最佳的光催化活性.CO和H_(2)的产率分别高达1.62×10^(4)和2.01×10^(4)μmol g^(−1)h^(−1).另外,Co纳米颗粒使得复合催化剂具有磁性,能够在外加磁场辅助下,快速、简易地分离回收.本工作有望为MOF衍生碳/金属复合催化剂的设计提供参考依据.
基金
financially supported by the National Key Research and Development Program of China(2020YFA0710303)
the National Natural Science Foundation of China(51972061,U1905215 and 52072076)。
作者简介
Fei-Fei Chen received his BS degree in 2014 from Xiamen University and his PhD degree in 2019 from Shanghai Institute of Ceramics,Chinese Academy of Sciences.Currently,he is a lecturer at Fuzhou University.His research interests include photocatalytic CO2 reduction,water purification,ecological materials,low-dimensional inorganic nanostructures,and metal-organic framework-derived catalysts.contributed equally to this work;Jianfeng Chen received his BS degree in 2018 from Fujian Agriculture and Forestry University.Currently,he is an MS candidate under the supervision of Prof.Yan Yu at Fuzhou University.His research interests include photocatalytic CO2 reduction,metalorganic frameworks,and metal-organic frameworkderived catalysts.contributed equally to this work;Corresponding authors:Lingyun Li received his BS degree in 2007 from Hefei University of Technology and his PhD degree in 2012 from Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences.Currently,he is an associate professor at Fuzhou University.His research interests include optical materials,laser crystals,metal-organic frameworks,and environmental remediation.emails:lilingyun@fzu.edu.cn;Corresponding authors:Yan Yu received her BS,MS,and PhD degrees from Fuzhou University.She was a postdoctoral fellow in 2010–2013 at Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences.Currently,she is a professor at Fuzhou University.Her research interests include environmental remediation,water purification,ecological materials,photocatalytic CO2 reduction and H2 production.emails:yuyan@fzu.edu.cn。
