PdIn intermetallic material with isolated single-atom Pd sites – A promising catalyst for direct formic acid fuel cell

Isolated single-atom Pd sites in intermetallic structures have the higher stability and unique catalytic properties. This study was designed to investigate the properties of isolated single-atom Pd sites in PdIn intermetallic toward formic acid oxidation compared to Pd3In and the pure Pd using density functional theory calculation. Unexpectedly, CO adsorption over PdIn catalyst is significantly lower than those over Pd3In and the pure Pd catalysts, an indication that CO poisoning is remarkably reduced on PdIn catalysts compared to the Pd3In and pure Pd catalysts. More importantly, PdIn catalyst with isolated single-atom Pd sites exhibits higher selectivity for formic acid oxidation to CO2 and inhibits CO formation, whereas Pd3In catalyst with Pd trimer presents better selectivity for formic acid oxidation to CO, which poisons Pd-based catalyst. Moreover, compared to the pure Pd catalyst, PdIn catalyst with isolated single-atom Pd sites not only has the higher activity and stability but also maximize atomic efficiency for noble metal Pd to reduce the catalyst cost. It is expected that the method applied in this research is beneficial to for the design and evaluation of intermetallic catalysts in clean energy technology development.