铁/氮共掺杂碳催化剂的制备及其电催化氧还原性能研究

Exploration on preparation of Fe-N/C and its electrocatalytic oxygen reduction performance

以硫酸铁铵和硫酸铵为金属源和氮源、以活性炭为碳载体,采用高温热处理法合成了铁/氮共掺杂碳(Fe-N/C)催化剂。采用X射线衍射仪和X射线光电子能谱仪表征催化剂的结构和组成,探究催化剂催化氧还原反应的活性位点。结果表明,Fe-吡啶氮-C结构是催化剂中最重要的催化活性位点。采用循环伏安法(CV)和线性扫描伏安法(LSV)研究了催化剂中氮含量对氧还原反应电催化活性的影响。结果表明催化剂Fe-N24.75/C-800催化活性最佳且峰电位达到0.91V(vs.RHE),接近Pt/C催化剂的活性,同时具有更好的甲醇耐受性,其催化氧还原反应的电子转移数为3.94。催化剂Fe-N24.75/C-800氧还原反应以4e转移、生成水的途径为主。

Fe/nitrogen doped carbon(Fe-N/C)catalysts were synthesized by pyrolyzing ammonium iron sulfate and ammonium sulfate supported on carbon at high temperature.X-ray diffraction and X-ray photoelectron spectroscopy were used to characterize the electrocatalysts in terms of the structure and composition and revealed the catalytic active sites of the catalysts.The characterization studies indicated that Fe-pyridinic-N-C was the most important of the catalytic active sites and responsible for the ORR catalytic activity of Fe-N/C in alkaline electrolyte.The effects of different nitrogen contents in the catalyst on the electrocatalytic activity of oxygen reduction were investigated by cyclic voltammetry(CV)and linear sweep voltammetry(LSV).The results shown that the catalyst Fe-N24.75/C-800 showed the best catalytic activity and the peak potential reached 0.91 V(vs.RHE),which was close to the activity of Pt/C catalyst and exhibited better methanol tolerance.The overall electron transfer number for catalyzed by the Fe-N24.75/C-800 was determined to be 3.94,suggesting that the oxygen reduction reaction on Fe-N24.75/C-800 catalyst involved the predominating 4-electron transfer pathway from O2 to H2 O.