(212c) Pt/Cu Single Atom Alloys for Highly Selective Formic Acid Dehydrogenation

Selective decomposition on metal catalysts is a critical step in formic acid’s application as a hydrogen storage molecule and for its use in direct formic acid fuel cells. Depending on the metal, formic acid can decompose via dehydrogenation to produce CO₂ and H₂, or dehydration to produce CO and H₂O. Typically, very high selectivity to dehydrogenation is preferred as reactively formed CO can poison the catalyst.  Cu surfaces are known to selectively decompose formic acid via dehydrogenation, however, despite being the most dominate facet of nanoparticles, Cu(111) has received little study. Pt surfaces exhibit greater reactivity for decomposition, but are not as selective resulting in increased catalyst poisoning. We report that formic acid on Cu(111) and Pt/Cu(111) selectively decomposes via dehydrogenation. The bare Cu(111) surface is 100% selective towards dehydrogenation, but not very active. Substitution of 1% of a monolayer of Pt into the Cu(111) surface results in a single-atom alloy (SAA) that maintains high selectivity and is ~six times more reactive. Increased Pt concentration improves reactivity further, but beyond the SAA regime selectivity towards dehydrogenation decreases. Our results show that Pt/Cu SAAs significantly improve the reactivity of Cu, while maintaining high selectivity towards dehydrogenation, therefore avoiding poisoning by CO.