新型多孔三聚氰胺负载MnCe用于高选择性电催化CO_(2)产甲酸

Novel Porous Melamine Foam Loaded with MnCe for Highly Selective Electrocatalytic CO_(2) to Formic Acid

本研究提出了一种尚未见报道的CO_(2)还原电催化剂及其构造,由MnCe作为活性位点,三聚氰胺泡沫(MS)作为载体前驱体的新型电极材料——MnCe-CMS(碳化MS)和MnCe-GOMS(氧化石墨烯活化MS),用于电催化CO_(2)还原研究.结果发现,MnCe-MS具有较宽的电位范围(-0.2~-3 V vs.RHE)及较好的产甲酸能力.对比以常用的碳布(CC)为载体的MnCe-CC,MnCe-CMS和MnCe-GOMS的甲酸生成速率分别提高到2.3、2.8倍,法拉第效率分别提高到2.3、2.5倍(MnCe-CC的最佳电位-0.4 V条件下),并且MnCe-GOMS在-0.6 V表现出最佳甲酸法拉第效率(75.72%).这归因于MS材料丰富的孔隙结构、较大的电化学表面积、易形成碳缺陷的特点,分析表明GO的掺入可以进一步增大这些优势;此外,在Mn、Ce共同作用下,有效促进电子传输、抑制析氢竞争反应、形成氧空位,有利于CO_(2)的吸附、活化与转化,从而促进甲酸生成.

A previously unreported CO_(2) reduction electrocatalyst consisting of MnCe as the active site and melamine foam(MS)as the carrier precursor is proposed.The MS were prepared into carbonized melamine foam(CMS)and graphene oxideactivated melamine foam(GOMS)by activation,respectively.And Mn and Ce were impregnated on the above substrates to synthesize MnCe-CMS and MnCe-GOMS catalysts for the electrocatalytic CO_(2) reduction to formic acid.It was found that MnCe-MS(MnCe-CMS and MnCe-GOMS)had a wide potential range(-0.2~-3 V vs.RHE)and better formic acid production ability.Among them,the Faraday efficiency of formic acid(FEf)on MnCe-CMS was 63.04%at-0.4 V,and the yield rate of formic acid(Yf)was 470.89μg•h^(-1)•cm^(-2) at-3.0 V.MnCe-GOMS showed better electrocatalytic activity,with a FEf of 75.72%at-0.6 V(when the Yf=661.99μg•h^(-1)•cm^(-2)),and optimal Yf of 746.9μg•h^(-1)•cm^(-2) at-0.8 V.In addition,no other products(e.g.,acetic acid,methanol,ethanol,CO,methane)were detected during the reaction,suggesting that MnCe-MS has a good formic acid selectivity.Compared with the MnCe-CC,which are based on the commonly used carbon cloth(CC)as a carrier,the Yf of MnCe-CMS and MnCe-GOMS were increased to 2.3 and 2.8 times,and the FEf were increased to 2.3 and 2.5 times,respectively,at the optimal potential of MnCe-CC of-0.4 V.This is attributed to the rich pore structure and large electrochemical surface area of the MS material,which can easily form carbon defects during the preparation,thus favoring the adsorption of CO_(2).Moreover,under the joint action of Mn and Ce,it effectively promotes electron transport,inhibits the competition reaction of hydrogen precipitation,and forms oxygen vacancies,which is conducive to the adsorption,activation and conversion of CO_(2),thus promoting the formation of formic acid.