ZIF-8基复合材料高效、稳定电催化还原CO_(2)

Efficient and stable electrocatalytic reduction of CO_(2)by ZIF-8 composites

电催化CO_(2)还原反应(eCO_(2)RR)受到催化剂本征活性以及传质的限制,导致材料的催化活性低、反应起始电位高等问题。我们以类沸石锌盐咪唑骨架(ZIF-8)材料为研究对象,探究了不同粒径ZIF-8材料的eCO_(2)RR性能。优选粒径为50 nm的ZIF-8材料,进一步引入碳纳米管(CNT)作为其导电基底材料,通过原位生长,构建了复合材料ZIF-8-50@CNT的多级孔结构和疏水界面。eCO_(2)RR实验结果表明,CNT的引入提高了催化剂的导电性,优化后的复合材料有效地降低了反应的起始电位。在-1.1 V(相对可逆氢电极(RHE))电位下,CO部分电流密度为15.6 mA·cm^(-2),ZIF-8-50@CNT催化剂的比表面活性提升了3.5倍(相比ZIF-8-50),塔菲尔斜率降低到136 mV·dec^(-1)。并且产物CO的选择性和稳定性得到了提高,在宽电势窗口-0.9~-1.2 V(vs RHE)内,CO的法拉第效率(FE)保持在80%以上。在10 h稳定性测试中,催化剂活性保持稳定,整体增强了复合材料eCO_(2)RR的性能。

Electrocatalytic CO_(2)reduction reaction(eCO_(2)RR)is still limited by the intrinsic activity and mass transfer of catalysts,resulting in low catalytic activity and high reaction onset potential.Herein,we explored the eCO_(2)RR performance of zeolite imidazole framework(ZIF-8)with different sizes.We took ZIF-8 with a particle size of 50 nm as the research object,and further introduced carbon nanotubes(CNT)as the conductive substrate material.The hierarchical porous structure and hydrophobic interface of ZIF-8-50@CNT were constructed by in-situ growth.The results of eCO_(2)RR experiment showed that the introduction of CNT improved the conductivity of the catalyst,and the optimized composite effectively reduced the onset potential of the reaction.At-1.1 V(versus reversible hydrogen electrode(RHE)),the partial CO current density of ZIF-8-50@CNT was 15.6 mA·cm^(-2),and the catalyst surface activity of ZIF-8-50@CNT catalyst is increased by 3.5 times that of ZIF-8-50,and the Tafel slope was reduced to 136 mV·dec^(-1).The selectivity and stability of the product CO were improved,and the Faraday efficiency(FE)of CO remained 80%at-0.9--1.2 V(vs RHE).In the 10 h stability test,the catalyst remained stable.The overall eCO_(2)RR performance of catalyst was enhanced.