Rational Design of Efficient Palladium Catalysts for Electroreduction of Carbon Dioxide to Formate

Abstract

The electrochemical reduction of CO 2 into renewable chemical products such as formic acid is an important and challenging goal. Traditional Pd catalysts suffer from CO poisoning, which leads to current density decay and short operating lifetimes. Here we explored the ability to control Pd nanoparticle surface morphology to amplify catalytic activity and increase stability in the electroreduction of CO 2 to formate. Through computational studies we have elucidated trends in intermediate binding which govern the selectivity and catalytic activity. We then rationally synthesized Pd nanoparticles having an abundance of highindex surfaces to maximize electrocatalytic performance. This catalyst displays a record current density of 22 mA/cm 2 at a low overpotential of −0.2 V with a Faradaic efficiency of 97%, outperforming all previous Pd catalysts in formate electrosynthesis. The findings presented in this work provide rational design principles which highlight morphological control of high-index surfaces for the effective and stable catalytic electroreduction of CO 2 to liquid fuels.

Catalyst electro-redeposition controls morphology and oxidation state for selective carbon dioxide reduction

“…It has been shown previously that sharp tips can improve bubble nucleation, concentrate stabilizing cations and exhibit high local fields, all of which increase current densities [27][28][29][30] . This high current density also promotes high local pH, limiting the protonation of bound CO that leads to methane formation 54 .…”

“…Furthermore, high-curvature structures, such as nanoneedles, promote nucleation of smaller gas bubbles 27 , and benefit from field-induced reagent concentration [28][29][30][31][32] , where high local negative electric fields concentrate positively charged cations to help stabilize CO 2 reduction intermediates 33 , enhancing CO 2 RR. However, combining high-curvature morphology with Cu + promotion to enable selective chemical conversion has yet to be explored.…”

Tuning of CO2 Reduction Selectivity on Metal Electrocatalysts

“…The selectivity of CO 2 electroreduction also strongly depends on the concentration of the electrolyte . Taking Pd metal as an example, its main product of CO 2 electroreduction can be altered from CO to formate with an FE over 90%, by increasing the concentration of KHCO 3 solution from 0.1 to 0.5 m . As the absorbed hydrogen atoms are involved with the formation of CO and formate on Pd catalysts, a higher supply of hydrogen atoms by the relatively concentrated HCO 3 − leads to an enhanced hydrogen adsorption at the electrode/electrolyte interface, thus making formate the exclusive product in 0.5 m KHCO 3 solution …”

“…This can be explained by the roughest and active‐site‐abundant nature of Ag(110) among these three facets, which provides the highest catalytic activity in the CO 2 reduction reaction. For Pd metals, the activity of CO 2 electroreduction is in the sequence of Pd(110) > Pd(111) > Pd(100) . Klinkova et al carried out density functional theory (DFT) studies of Pd(111), Pd(110), Pd(100), Pd(211) nanoparticles and a Pd 19 cluster to reveal the correlation between the surface atomic coordination and catalytic performance of CO 2 reduction .…”

Electrocatalytic CO2 Reduction to Formate at Low Overpotentials on Electrodeposited Pd Films: Stabilized Performance by Suppression of CO Formation

“…[27] However, minor production of CO still inhibitst he CO 2 reduction and deactivates the electrode over time. [28] The present work introduces af acile and efficient methodf or the preparation of Pd nanoparticle films Palladium nanoparticles are effective for catalytic CO 2 reduction. [26] Very recently,S argent and co-workers found that the surfacem orphologyo fP dn anoparticles could highly affect the selectivity; ah igh-index surfacei mproved the stability for formate formation without the production of CO in aC O 2 electroreduction performed for 1h.…”