Do Ni/Cu and Cu/Ni Alloys have Different Catalytic Performances towards Water-Gas Shift? A Density Functional Theory Investigation

Density functional calculations were preformed to investigate whether adding Ni into a Cu surface (denoted as Cu/Ni) or adding Cu into a Ni surface (Ni/Cu) is more efficient for catalyzing the water‐gas shift (WGS)? The reactions of water dissociation and monoxide dissociation were selected to assess the activity and selectivity towards WGS, respectively. Our results show that Ni‐atom modification of surfaces is thermodynamically favorable for both reactions. Kinetically, compared with pure Cu, water dissociation is greatly facilitated on Ni‐modified surfaces, and the activity is insensitive to the Ni concentration; however, monoxide dissociation is not well‐promoted on one Ni‐atom‐modified surfaces, but two Ni‐atom modification can notably decrease the dissociation barriers. Overall, on the basis of these results, we conclude that 1) the catalytic performance of bimetallic metals is superior to monometallic ones; 2) at the same Ni concentration on the surface, Cu/Ni and Ni/Cu alloys have almost the same performance towards WGS; and 3) to acquire high WGS performance, the surface Ni atoms should either be low in concentration or highly dispersed. Shifting gear: First‐principles calculations are employed to investigate the water‐gas shift performance with Cu/Ni and Ni/Cu alloys.