Enhanced CH₄ Selectivity in CO₂ Hydrogenation on Bimetallic Pt–Ni Catalysts with Pt Nanoparticles Modified by Isolated Ni Atoms

Catalytic CO 2 hydrogenation is a promising way to produce chemicals and has recently received much attention; however, designing catalysts with special product selectivity still remains a challenge. Here, we interestingly found that the Pt–Ni/γ-Al 2 O 3 catalyst tended to have high CH 4 selectivity, while both Pt/γ-Al 2 O 3 and Ni/γ-Al 2 O 3 had high CO selectivity. The characterization results showed that the Pt–Ni bimetallic catalyst was composed of Pt nanoparticles with surrounding Ni atoms. The results of in situ diffuse reflectance Fourier transform infrared spectroscopy showed the direct disassociation of CO 2 to CO on the Pt/γ-Al 2 O 3 and the decomposition of formate species to CO on Ni/γ-Al 2 O 3 . However, the presence of Pt–Ni bimetallic sites changed the hydrogenation pathway, in which the electronic interaction between Pt particles and surrounding Ni atoms promoted the further hydrogenation of formate species to CH 4 . This study provides insights into the understanding of the mechanisms of CO 2 hydrogenation on bimetallic catalysts.