碳纳米管上原位沉积钯-钴-镍纳米颗粒及其对乙醇氧化的电活性

In Situ Formation of Ternary Pd-Ni-Co Nanocatalyst on MWCNT for Ethanol Electro-oxidation in Alkaline Media

以水合肼为还原剂,在水和乙醇的混合溶液中制备多壁碳纳米管(MWCNT)负载的纳米镍(Ni/MWCNT)和纳米镍钴(Ni-Co/MWCNT)颗粒,然后将它们分别与氯化钯溶液反应,形成的钯纳米颗粒原位沉积在MWCNT表面,从而得到MWCNT负载的PdNi/MWCNT和Pd-Ni-Co/MWCNT催化剂。SEM和TEM图像显示,MWCNT上的催化剂颗粒是由5~10 nm的小颗粒团聚而成的30~100 nm的大颗粒,三金属催化剂的粒径比双金属的粒径小,在MWCNT上的分散度更高。ICP和EDS分析显示,Pd直接还原并包覆在纳米镍和纳米镍钴表面;采用循环伏安和计时电流技术,研究了催化剂在碱性溶液中对乙醇氧化的电催化活性,结果表明,Pd-Ni-Co/MWCNT催化剂对乙醇氧化具有强的电催化活性,乙醇氧化对应的峰电流密度达101.8 m A·cm^(-2),并且催化剂催化活性稳定。

Ni/MWCNT and NiCo/MWCNT nanoparticles were firstly prepared by chemical reduction method with hydrazine as reductant in a mixture medium of water and alcohol using Multi-walled carbon nano-tubes （MWCNTs） as the support. PdNi/MWCNT and PdNiCo/MWCNT catalysts were then prepared through an in-situ reduction by the reaction of the Ni/MWCNT and NiCo/MWCNT with the aqueous PdCl2 solution respectively. SEM and TEM images show that the large aggregates on the surface of MWCNTs with the diameter of 30-100 nm are composed of small particles with the diameter of 5-10 nm. The ternary PdNiCo catalyst presents the smaller diameter than PdNi catalyst, as well as the better dispersity on MWCNT. ICP and EDS analyses reveal that Pd nanoparticles are directly reduced and coated on the surface of Ni and NiCo nanoparticles. The electrochemical activity of the catalysts towards ethanol oxidation in alkaline media has been examined by cyclic voltammetry （CV） and chronoamperometry （CA） methods. PdNiCo/MWCNT catalyst presents an anodic peak current density of 101.8 mA. cm-2 for ethanol oxidation in alkaline medium. Long-term cyclic voltammetric tests show superior stability of Pd nanoparticles upon addition of Ni and NiCo to the support.