CO2 dissociation over PtxNi4−x bimetallic clusters with and without hydrogen sources: A density functional theory study

Recently, CO2 activation and conversion is a well-attractive reaction that is of both scientific and industrial importance. In our present work, CO2 dissociation with and without hydrogen sources over Pt-Ni bimetallic catalysts have been studied by DFT systematically at the atomic scale. To address these processes, the detailed catalytic mechanisms of three bimetallic clusters Pt3Ni1, Pt2Ni2, Pt1Ni3 to CO2 dissociation have been investigated, and their catalytic activities are compared with monometallic Pt4 and Ni4 clusters. The activation barrier values of CO2 dissociation with and without hydrogen sources on bimetallic PtxNi4−x clusters are both between the values of monometallic Pt4 and Ni4 clusters. Evidently, CO2 dissociation with hydrogen sources is much easier to be carried out than that without hydrogen sources for all five clusters. Catalysis for CO2 dissociation needs to be combined with hydrogen sources. In addition, with the increasing number of Ni atoms in PtxNi4−x clusters, the activation barriers present a moderate rise, indicating that Ni doping Pt cluster has a slight effect on the activity of Pt cluster for CO2 dissociation. As a result, the activity of bimetallic Pt-Ni for the reaction might be slightly lower than monometallic Pt, while, the cost of noble metal Pt catalysts will decrease with the addition of Ni.