Mild and selective hydrogenation of CO2 into formic acid over electron-rich MoC nanocatalysts

富电态MoC基纳米催化剂高效和高选择性催化CO2加氢合成甲酸

The direct hydrogenation of CO2 using H2 gas is a one-stone-two-birds route to produce highly valueadded hydrocarbon compounds and to lower the CO2 level in the atmosphere.However,the transformation of CO2 and H2 into hydrocarbons has always been a great challenge while ensuring both the activity and selectivity over abundant-element-based nanocatalysts.In this work,we designed a Schottky heterojunction composed of electron-rich MoC nanoparticles embedded inside an optimized nitrogen-doped carbon support(MoC@NC)as the first example of noble-metal-free heterogeneous catalysts to boost the activity of and specific selectivity for CO2 hydrogenation to formic acid(FA)in liquid phase under mild conditions(2 MPa pressure and 70℃).The MoC@NC catalyst with a high turnover frequency(TOF)of 8.20 molFA molMoC^-1 h^-1 at 140℃ and an excellent reusability are more favorable for real applications.

CO2的直接加氢还原是一个一石二鸟的策略,既可以制备高附加值的化学品,同时又有效地利用了该温室气体.提高非贵金属催化剂催化CO2加氢转化的活性及产物的选择性仍是一项巨大的挑战.本文设计了一种超分子自组装的合成方法并成功制备出一种肖特基型异质结催化剂,即由氮掺杂碳载体支撑的富电中心MoC纳米材料(MoC@NC),是第一例非贵金属催化剂实现了在较温和条件下(2 MPa和70℃)液相还原CO2合成甲酸.实验和理论计算结果表明,MoC纳米粒子和氮掺碳载体界面间电荷转移,提高了MoC表面电荷密度,对CO2分子的吸附、活化和反应路径的调控起到了关键作用.在140℃时,肖特基型催化剂MoC@NC的反应转化频率高达8.20 molFA molMoC^-1 h^-1,展现出了高活性和高选择性.此外,良好的循环稳定性说明复合催化剂MoC@NC具备潜在的实际应用价值.