N,O共修饰的Ni纳米颗粒/氮掺杂介孔碳CO2高效电还原催化剂

利用可再生电力能源将CO2电还原(CO2RR)为高附加值燃料和化学品(CO、甲酸盐和碳氢化合物等)是一种高效、绿色的CO2资源化利用新技术.然而,由于CO2分子中双键难以活化,且存在析氢竞争反应,即使对于CO2电还原为CO这一简单反应,除少数贵金属(Au、Ag和Pd及其合金)外,当前大多数电催化剂对产物CO的选择性和活性仍较低.因此,开发高效、稳定且廉价的CO2RR催化剂具有重要意义.过渡金属Ni储量高、成本低,是潜在的CO2RR催化剂.然而,受限于Ni对*H及*CO等中间物种相对强的吸附能力,Ni基催化剂催化生成产物CO的活性和选择性较低.近年来研究表明,通过对Ni基材料进行表面修饰,可以调控Ni表面与中间物种的吸附强度,从而有效提升Ni基催化剂对CO2RR反应的活性和选择性.鉴于此,本文通过N,O共调控的策略对负载于N掺杂介孔碳上的Ni纳米颗粒进行表面修饰,制得的N,O-Ni/CMK3催化剂能够高效、高选择性地将CO2电还原为CO.X射线衍射、高角度环形暗场扫描透射电子显微镜和X射线光电子能谱等表征结果表明,N,O-Ni/CMK3中的Ni纳米颗粒由金属Ni核和N掺杂的NiO壳组成,即Ni纳米颗粒表面被N,O共调控,这种独特的表面使其表现出与金属Ni不同的CO2RR催化性能.电化学测试结果表明,在0.5 M KHCO3电解液中,N,O-Ni/CMK3催化剂表现出较好的选择性(生成CO法拉第效率达97％)、活性(CO分电流密度为13.01 mA cm?1)和转换频率(4.25 s?1).表征结果表明,N,O共同调控的Ni是该催化反应的活性中心.此外,得益于N,O共调控的Ni表面,N,O-Ni/CMK3催化剂比O调控的Ni催化剂具有更好的电化学稳定性.本文通过调节Ni催化剂的表面化学环境来调控催化剂与反应中间物种的吸附强度,显著提高了Ni基催化剂对CO2RR反应的催化活性和CO选择性,为开发高活性、高选择性的过渡金属催化剂提供了新思路.

Surface regulated Ni nanoparticles on N-doped mesoporous carbon as an efficient electrocatalyst for CO2 reduction

Low cost, highly selective and efficient electrocatalysts for CO2 reduction reaction (CO2RR) is crucial for lowering the global carbon footprint and mitigating energy shortages. Here, we first report a highly selective and efficient electrocatalyst for CO2RR to CO using a surface-regulated Ni nanopar-ticles supported on N-doped CMK-3 (N,O-Ni/CMK3). Compared with most Ni metal catalysts previ-ously reported with severe competitive hydrogen evolution during the CO2RR, the N,O-Ni/CMK3 catalyst presents a superior CO faradaic efficiency of about 97％, a high CO partial current density (13.01 mA cm–1) and turnover frequency (4.25 s–1). The comprehensive characterization provides evidence that the N,O co-regulated Ni acts as the active center. Taking advantage of the N, O co-regulated chemical environment, N,O-Ni/CMK3 also displays a decent stability at negative poten-tials. Our work paves a novel approach for developing transition metal catalysts for CO2RR with enhanced activity and selectivity via regulating surface chemical environment.