Selective Formic Acid Dehydrogenation on Pt-Cu Single-Atom Alloys

Abstract

Formic acid is a potential hydrogen storage molecule which dehydrogenates to form CO2 and H2 on metal surfaces. However, it can also decompose via a competing dehydration reaction that forms CO and H2O, reducing the amount of H2 produced and poisoning the catalyst with CO. Formic acid re-formation to hydrogen is typically performed by Pt and Pd catalysts, which while highly active for dehydrogenation also catalyze dehydration. Cu is typically not utilized, as it requires prohibitively high temperatures, although Cu surfaces are very selective toward dehydrogenation. We studied the reaction of formic acid on single-atom alloys (SAAs), consisting of single Pt atoms substituted into a Cu lattice. Surface science studies allowed us to relate alloy structure to reactivity and selectivity and visualize reaction intermediates. These experiments revealed that SAAs are able to selectively dehydrogenate formic acid with a 6-fold increase in yield in comparison to Cu. This increase in conversion is due to a more facile dehydrogenation of formic acid to formate on the SAA surface (120 K vs 160 K on Cu(111)). We acquired quantitative desorption and molecular scale imaging data showing spillover of formate from Pt sites to Cu. Increasing the Pt concentration beyond the SAA regime resulted in loss of selectivity. These results prompted us to test SAA nanoparticle (NP) catalysts under realistic conditions. However, only a slight increase in conversion was observed between pure Cu and Pt-Cu SAA NPs. In our surface science studies, dehydrogenation of formate to CO2 and H2 did not occur until above 400 K on both the SAA and pure Cu surfaces, indicating that Pt sites do not catalyze this rate-limiting step. While SAAs do not offer increased reactivity for formic acid dehydrogenation, they do offer significantly lower barriers for O–H bond breaking, which holds promise for other dehydrogenation reactions.

Anchoring Pt Single Atoms on Te Nanowires for Plasmon‐Enhanced Dehydrogenation of Formic Acid at Room Temperature

“…[1][2][3][4][5][6][7][8][9][10][11] Noble metal based catalysts such as Ir complexes, Ru-biaryl sulfonated phosphines, bimetallic Pd/M (M = late transition fcc metal), PdAg nanoparticles, Figure 4. [1][2][3][4][5][6][7][8][9][10][11] Noble metal based catalysts such as Ir complexes, Ru-biaryl sulfonated phosphines, bimetallic Pd/M (M = late transition fcc metal), PdAg nanoparticles, Figure 4.…”

“…[2][3][4][5][6] Such catalysts suffered from the elevated temperature (60-150 °C) to enhance their performance, which became troublesome barriers to their usages in a wider range. [2][3][4][5][6] Such catalysts suffered from the elevated temperature (60-150 °C) to enhance their performance, which became troublesome barriers to their usages in a wider range.…”

“…Modulating the metal-support interaction is a feasible approach to construct efficient supported catalysts. [1][2][3][4][5][6][7][8][9][10][11] Noble metal based catalysts such as Ir complexes, Ru-biaryl sulfonated phosphines, bimetallic Pd/M (M = late transition fcc metal), PdAg nanoparticles, Figure 4. [7] Besides, NiPd ultrafine particles supported on NH 2 -functionalized and N-doped graphene oxide were capable of catalyzing HCOOH selective dehydrogenation at 25 °C.…”

“…Figure 1A shows a high-angle annular dark-field Adv. 2019, 6,1900006 Figure 1. 2019, 6,1900006 Figure 1.…”

“…2019, 6,1900006 To investigate the interaction between reactants and 1.1%Pt/ Te, 4.6%Pt/Te, and 32.0%Pt/Te, we conducted in situ diffuse reflectance infrared Fourier transform (DRIFT) measurements. Sci.…”