Paper SS+AS+EN-WeA12
Pt/Cu Single Atom Alloys for Highly Selective Formic Acid Dehydrogenation

Wednesday, October 21, 2015, 6:00 pm, Room 113

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 a dehydrogenation pathway to produce CO₂ and H₂, or a dehydration pathway to produce CO and H₂O. For most applications, very high selectivity to dehydrogenation is preferred as reactively formed CO from dehydration can poison the catalyst. The Cu(110) surface is 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 to 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. We find the bare Cu(111) surface to be 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 this high selectivity and is ~six times more reactive than Cu(111). Higher coverages of Pt improve reactivity further, but beyond the single atom regime the selectivity towards dehydrogenation decreases and dehydration is observed. Our results show that Pt/Cu SAAs significantly improve the reactivity of Cu, while also maintaining high selectivity towards dehydrogenation, therefore avoiding catalyst poisoning by CO. Based on our results, real nanoparticle catalysts designed on the SAA principle are expected to be promising candidates for formic acid dehydrogenation.