Comparative theoretical study of formic acid decomposition on PtAg(111) and Pt(111) surfaces

Pt-based catalysts are known as the best electrocatalysts for formic acid (HCOOH) oxidation. Maximizing their use efficiency and reducing the CO poisoning effect are highly desirable, however, very challenging. Aiming at these interesting issues, this work presents a theoretical study of the catalytic decomposition of HCOOH on an ideal single-atom model catalyst of PtAg nanostructures, which consists of isolated Pt atoms anchored to an Ag(111) surface and is referred to as PtAg(111). The barrier of the rate-determining step of HCOOH decomposition to CO on PtAg(111) is calculated to be 0.38 eV, which is not significantly different from that on a pure Pt(111) surface, 0.35 eV. On the other hand, the barrier of HCOOH decomposing to CO on PtAg(111) is found to be higher than that on pure Pt(111), 0.83 vs. 0.67 eV. These results indicate that the single-atom PtAg(111) (Pt-decorated Ag(111) surface) presents promising catalytic performance for HCOOH oxidation, which promotes HCOOH dehydrogenation to CO as good as pure Pt(111) and inhibits HCOOH dehydration to undesirable CO that poisons the catalyst. The present results rationalize the experimental observation that Pt-Ag alloy electrocatalysts show improved catalytic performance toward HCOOH oxidation, and provide a clue for the rational design of Pt-based single-atom catalysts.