用于高效电催化甘油氧化的CuCoN_(0.6)/CP催化剂

Enhanced electrocatalytic glycerol oxidation on CuCoN_(0.6)/CP at significantly reduced potentials

随着人口的不断增长和经济的高速发展,化石燃料(煤、石油和天然气等)的使用量急剧增加,能源短缺、温室效应、环境污染等问题日益严重.因此,发展可再生的清洁能源以取代化石燃料对人类社会的可持续发展至关重.由于氢气具有能量密度高、来源丰富、清洁无毒等优点,有望成为替代化石燃料的最有前景的可再生能源.然而,目前氢气主要来自化石燃料的蒸汽重整,该过程需要高温高压,而且产生的氢气杂质含量高、纯化过程复杂,不能满足绿色化学生产的要求.利用可再生电力电解水制氢是一种绿色高效的制氢方式,但其实际应用受限于动力学过程缓慢的阳极析氧反应(OER).因此,采用动力学过程更快的有机小分子(甲醇、乙二醇、甘油等)氧化反应来替代OER,不仅可以降低制氢能耗,还能在制氢的同时获得高附加值氧化产物.本文采用水热结合高温焙烧法制备了负载于导电碳纸上CuCoN_(0.6)(CuCoN_(0.6)/CP)纳米线催化剂.采用扫描电子显微镜与透射电子显微镜等对催化剂形貌进行表征.结果表明,表面粗糙的CuCoN_(0.6)纳米线组成的纳米小球与碳纸紧密结合.X射线光电子能谱结果表明,Cu^(+)成功引入到CuCoN_(0.6)/CP中.电化学性能测试结果表明,CuCoN_(0.6)/CP仅需1.07 V的阳极电位即可达到10 mA cm-2的电流密度.此外,CuCoN_(0.6)/CP具有较小的电荷转移电阻(93.45Ω)以及较大的电化学活性表面积(109.6 mF cm-2),并且目标产物甲酸的法拉第效率达到90.0%.循环伏安和原位拉曼光谱测试结果表明,在电催化过程中催化剂原位重构形成CoOOH活性位点,Cu^(+)和CO_(2)+的氧化促进了活性羟基(OH*)的形成,从而提升了甘油电催化氧化性能.原位红外光谱测试结果表明,甘油氧化的反应路径如下:甘油首先氧化生成甘油醛,再氧化生成甘油酸,其中甘油酸经过C-C键断裂生成乙醇酸和甲酸,然后乙醇酸经过C-C键的断裂生成甲酸,最后成功分离出高纯度、高附加值的产品二甲酸钾.综上,本文通过精心设计非贵金属催化剂,提高其在碱性条件下的催化活性,为有机小分子的电催化转化以及非贵金属电催化剂的设计提供了参考,对后续研究具有参考意义.

Electrocatalytic alcohol oxidation coupled with the hydrogen evolution reaction,wherein a thermodynamically favorable oxidation reaction replaces the sluggish kinetics of the oxygen evolution reaction,has recently attracted considerable attention.However,the development of nonprecious-metal electrocatalysts capable of delivering much lower oxidation potentials holds great significance.In this study,we proposed and developed CuCoN_(0.6)nanowires loaded on conductive carbon paper(denoted as CuCoN_(0.6)/CP)as an efficient catalyst for selective glycerol oxidation to formate.Our catalyst achieved a remarkably high faradic efficiency of 90.0%towards formate production.More notably,it required an anode potential as low as 1.07 V to achieve a current density of 10 mA cm−2,a significantly lower potential than that reported in the literature.Experimental characterizations reveal that the oxidations of Cu+and Co2+ions promoted the formation of reactive hydroxyl species,which are responsible for the substantially reduced oxidation potential and enhanced glycerol oxidation performance.Furthermore,we investigated the reaction pathway of glycerol oxidation and structural changes in the catalysts.The catalyst reconstruction led to the formation of CoOOH,which is considered as the active site for glycerol oxidation.Finally,we successfully separated high-purity and value-added potassium diformate product.This work not only advances the electrocatalytic conversion of biomass-derived alcohols but also provides insights into the design of electrocatalysts with broad applications.