双二苯基-1-甲基咪唑膦氯化镍的制备及其电催化还原CO_2的研究

Preparation of Ni(dpim)_2Cl_2 Complex for the Electrocatalytic Reduction of CO_2

以二苯基-1-甲基咪唑膦(dpim)为配体制备了一种新型的配合物催化剂Ni(dpim)_2Cl_2.循环伏安研究表明,Ni(dpim)2Cl2配合物在氮气气氛下表现出两步还原的电化学行为,在-0.7 V下为两电子的不可逆还原,在-1.3 V下为单电子准可逆还原.向电解液中通入CO_2后,在-1.3 V下的还原峰变得不可逆,且其峰电流从0.48 m A·cm^(-2)增大到0.55 m A·cm^(-2).在质子源(CH3OH)存在的条件下,该还原峰电流可继续增大到0.72 m A·cm^(-2).该研究结果表明,Ni(dpim)_2Cl_2配合物对CO_2还原具有良好的电催化性能,且其电催化还原过程符合ECE机理.在-1.3 V下恒电位电解得到的还原产物主要为CO,催化转换频率(Turnover of Frenquency,TOF)为0.17 s^(-1).

A new Ni（dpim）2Cl2 complex using 2-（diphenylphosphino）-1-methylimidazole（dpim） as a ligand was prepared and served as a catalyst for the electrochemical reduction of CO2. The electrochemical redox behavior of Ni（dpim）2Cl2 in CH3CN/TPABF_4 solution under nitrogen atmosphere showed the two-electron irreversible reduction at-0.7 V and one-electron quasi-reversible reduction at-1.3 V. After bubbling CO2 into the electrolyte, the reduction peak appeared at-1.3 V became irreversible and the peak current increased from 0.48 m A·cm^（-2） to 0.55 m A·cm-2. Moreover, the peak current at-1.3 V could further increase to 0.72 m A·cm^（-2） in the presence of proton source（CH3OH）. These observations indicate that the Ni（dpim）2Cl2 exhibited a good electrocatalytic performance toward CO2 reduction and the electrocatalytic reduction process followed the ECE mechanism. The reduction products obtained by the potentiostatic electrolysis（at-1.3 V） were identified to be mainly CO with the catalytic conversion frequency of 0.17 s^（-1）.