气相CrxN−(x=2~7)阴离子团簇与CO2的反应研究

The study on the reaction of gas-phase CrxN−(x=2–7)anion clusters with CO2

室温下将二氧化碳(CO2)高效还原为一氧化碳(CO)对于CO2资源的利用至关重要.本文通过高分辨率反射式飞行时间质谱结合密度泛函理论(DFT)计算,在热碰撞条件下利用铬氮阴离子团簇CrxN−(x=2~7)实现了连续还原两个CO2分子.CrxN−(x=2~7)和Cr2NH−团簇可以与CO2反应分别生成CrxNO−/CO和Cr2NHO−/CO,之后中间产物三元阴离子CrxNO−可以进一步还原第二个CO2生成CrxNO2−和CO分子.上述连续反应具有高反应活性,并且无CO2吸附产物生成.随着团簇中铬原子数目从2增加到7(Cr2N−~Cr7N−),团簇的反应活性先增加后略有降低.DFT计算给出了该类活性阴离子的结构和连续反应的反应机理.这项工作为逆水煤气催化剂表面活性位的设计提供了新的思路.

Efficient reduction of CO2 to CO under room temperature is of great importance for CO2 utilization.For the first time,the CO2 reduction by multinuclear transition-mental nitride cluster anions CrxN−(x=2–7)under thermal-collision conditions has been identified by applying mass spectrometry in conjunction with density functional theory(DFT)calculations.The CrxN−(x=2–7)and Cr2NH−clusters can react with CO2 to generate CrxNO−and CO,and the intermediate ternary anions CrxNO−can further reduce another CO2 to form CrxNO2−and one CO molecules.All of these consecutive reactions are with high reactivity,and no CO2 adsorbate is formed.As the cluster size increases from Cr2N−to Cr7N−,the cluster reactivity first increases and then decreases slightly.The DFT calculations predict the structures of these reactive anions and reaction mechanisms for the consecutive reactions.This work shades new light into the design of active sites on reverse water gas shift catalysts.