铝空气电池用Ag@Cu_(2+1)O/MWNTs氧还原催化剂的制备和电催化性能

Preparation and electrocatalytic performance of Ag@Cu_(2+1)O/MWNTs catalysts towards oxygen reoxygen reduction catalyst for aluminum-air battery

以四羟甲基氯化磷(THPC)为还原剂,多壁碳纳米管(multi-walled carbon nanotubes,MWNTs)为载体,采用一步法制备Ag@Cu_(2+1)O/MWNTs催化剂,用X射线衍射仪、透射电镜、X射线光电子能谱仪等对催化剂结构、形貌及组成进行表征,并进行负载量测试及循环伏安法(cyclic voltammetry,CV)、线性伏安法(linear sweep voltammetry,LSV)等氧还原反应(oxidation-reduction reaction,ORR)测试。结果表明,Ag@Cu_(2+1)O/MWNTs催化剂的Ag和Cu_(2+1)O负载量(质量分数,%)分别为9.32%和5.90%,Ag@Cu_(2+1)O的平均粒径约为7 nm。Ag@Cu_(2+1)O/MWNTs在碱性介质中催化直接四电子氧还原过程,LSV半波电位为0.75 V,1 600 r/min下的极限扩散电流密度接近5.5 mA/cm^(2),Tafel斜率为92 mV/dec,与20%Pt/C相当,优于Ag负载量为17.5%的Ag/MWNTs催化剂。Ag@Cu_(2+1)O/MWNTs具有与20%Pt/C相当的稳定性和更强的耐甲醇毒化能力。作为铝空气电池阴极催化剂时,表现出与20%Pt/C相当的功率密度(148.7 mW/cm^(2))、容量(1 260 mAh/g)和稳定性。

Ag@Cu_(2+1)O/MWNTs catalysts were prepared by one-step method with THPC as reducing agent and MWNTs as support.The structure,morphology,and composition of the catalyst were characterized by X-ray diffractometry,transmission electron microscopy,and X-ray photoelectron spectroscopy.In addition,the catalyst load and ORR performance were tested.It can be seen that the Ag and Cu_(2+1)O loading (mass fraction,%) of Ag@Cu_(2+1)O/MWNTs catalyst are 9.32%and 5.90%,respectively,and the average particle size of Ag@Cu_(2+1)O catalyst is about 7 nm.Ag@Cu_(2+1)O/MWNTs catalyzes direct four-electron oxygen reduction in alkaline medium,the half-wave potential of Ag@Cu_(2+1)O/MWNTs is 0.75 V,the limit diffusion current density is close to 5.5 mA/cm^(2) at 1 600 r/min and the slope of Tafel is 92 mV/dec,which is equivalent to the performance of 20%Pt/C and is more outstanding than Ag/MWNTs catalyst with 17.5%Ag loading capacity.Meanwhile,Ag@Cu_(2+1)O/MWNTs has the same stability as 20%Pt/C and better resistance to methanol poisoning.When used as cathode catalyst for aluminum-air battery,Ag@Cu_(2+1)O/MWNTs exhibits power density (148.7 mW/cm^(2)),capacity (1 260 mAh/g) and stability which is comparable to that of 20%Pt/C.