Electrolysis Can Be Used to Resolve Hydrogenation Pathways at Palladium Surfaces in a Membrane Reactor

Aoxue Huang; Yang Cao; Roxanna S Delima; Tengxiao Ji; Ryan P Jansonius; Noah J J Johnson; Camden Hunt; Jingfu He; Aiko Kurimoto; Zishuai Zhang; Curtis P Berlinguette

doi:10.1021/jacsau.0c00051

Electrolysis Can Be Used to Resolve Hydrogenation Pathways at Palladium Surfaces in a Membrane Reactor

JACS Au. 2021 Feb 26;1(3):336-343. doi: 10.1021/jacsau.0c00051. eCollection 2021 Mar 22.

Authors

Aoxue Huang¹, Yang Cao^{1

2}, Roxanna S Delima^{2

3}, Tengxiao Ji¹, Ryan P Jansonius¹, Noah J J Johnson¹, Camden Hunt^{1

2}, Jingfu He¹, Aiko Kurimoto¹, Zishuai Zhang¹, Curtis P Berlinguette^{1

2

3

4}

Affiliations

¹ Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada.
² Stewart Blusson Quantum Matter Institute, The University of British Columbia, 2355 East Mall, Vancouver, BC V6T 1Z4, Canada.
³ Department of Chemical & Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, BC V6T 1Z3, Canada.
⁴ Canadian Institute for Advanced Research (CIFAR), 661 University Avenue, Toronto, M5G 1M1 Ontario, Canada.

Abstract

For common hydrogenation chemistries that occur at high temperatures (where H₂ is adsorbed and activated at the same surface which the substrate must also adsorb for reaction), there is often little consensus on how the reactions (e.g., hydro(deoxy)genation) actually occur. We demonstrate here that an electrocatalytic palladium membrane reactor (ePMR) can be used to study hydrogenation reaction mechanisms at ambient temperatures, where the catalyst does not necessarily undergo structural reorganization. The ePMR uses electrolysis and a hydrogen-selective palladium membrane to deliver reactive hydrogen to a catalyst surface in an adjacent compartment for reaction with an organic substrate. This process forms the requisite metal-hydride surface for hydrogenation chemistry, but at ambient temperature and pressure, and without a H₂ source. We demonstrate the utility of this analytical tool by studying the hydrogenation of benzaldehyde at palladium nanocubes with dimensions of 13-24 nm. This experimental design enabled us to resolve that the alcohol product forms at the facial sites, whereas the hydrodeoxygenation step occurs at edge sites. These observations enabled us to develop the first site-specific definition of how a carbonyl species undergoes hydro(deoxy)genation.