Periodic density functional theory (DFT) calculations were performed to investigate the facet effect on CO₂ adsorption, dissociation and hydrogenation over Fe catalysts. The energetically most stable configurations of CO₂ and H₂ adsorption over different Fe facets were identified from which we observed that CO₂ adsorption on Fe(211) and Fe(111) is much stronger than other facets, indicating more sufficient activation of CO₂ on these two surfaces. CO₂ adsorption stability was found to be impacted by the surface coverage of H* on these Fe facets, showing that when surface H* coverage exceeds to certain percentage, CO₂ adsorption is largely weakened whilst the electrons transfer from the Fe surface to CO₂ becomes decreased. These results suggest that an appropriate H₂-CO₂ co-adsorption equilibrium is important for effective activation of reactants. Based on the examination of CO₂ dissociation and hydrogenation on these Fe facets, the Fe(111) is potentially the most active facet for CO₂ conversion due to a lower barrier for HCOO* formation via CO₂ hydrogenation while this facet is also catalytically more active for activating CO₂. Fe(110) and Fe(100) exhibit more facile ability to dissociate CO₂ to CO* while kinetically competitive formation of CO* and HCOO* was observed over Fe(211). The present work demonstrates that the facet of Fe catalysts can impact the molecular adsorption, activation and conversion path in CO₂ hydrogenation and thus can alter the product selectivity.

进行了周期性密度泛函理论（DFT）计算，以研究刻面效应对Fe催化剂上CO ₂吸附，离解和氢化的影响。确定了在不同的Fe面上CO ₂和H _2的吸附在能量上最稳定的配置，从中我们观察到，Fe（211）和Fe（111）上的CO ₂吸附比其他方面强得多，表明CO _2的活化更充分在这两个表面上。发现这些Fe面上H *的表面覆盖率会影响CO _2的吸附稳定性，表明当表面H *覆盖率超过一定百分比时，CO ₂当电子从Fe表面转移到CO ₂时，吸附作用大大减弱。这些结果表明适当的H ₂ -CO ₂共吸附平​​衡对于反应物的有效活化是重要的。根据对这些Fe平面上的CO ₂分解和氢化的检查，Fe（111）可能是CO ₂转化最活跃的平面，这是由于通过CO ₂氢化形成HCOO *的势垒较低，而Fe（111）催化性也更高。激活CO _2的活性剂。Fe（110）和Fe（100）表现出更容易分解CO _2的能力在Fe（211）上观察到CO *和HCOO *的动力学竞争性形成。目前的工作表明，Fe催化剂的表面会影响CO ₂加氢中的分子吸附，活化和转化路径，从而改变产物的选择性。