CO₂ Electrolysis via Surface-Engineering Electrografted Pyridines on Silver Catalysts

Abstract

The electrochemical reduction of carbon dioxide (CO2) to value-added materials has received considerable attention. Both bulk transition metal catalysts, and molecular catalysts affixed to conductive non-catalytic solid supports, represents a promising approach towards electroreduction of CO2. Here, we report a combined silver (Ag) and pyridine catalyst through a green and irreversible electrografting process, which demonstrates enhanced CO2 conversion versus the individual counterparts. We find by tailoring the pyridine carbon chain length, a 200 mV shift in the onset potential is obtainable compared to the bare silver electrode. A 10-fold activity enhancement at -0.7 V vs RHE is then observed with demonstratable higher partial current densities for CO indicating a co-catalytic effect is attainable through the integration of the two different catalytic structures. We extended performance to a flow cell operating at 150 mA/cm 2 , demonstrating the approach's potential for substantial adaption with various transition metals as supports, and electrografted molecular co-catalysts.

In Situ Deposited Polyaromatic Layer Generates Robust Copper Catalyst for Selective Electrochemical CO2 Reduction at Variable pH

“…Electrografting molecules permits the growth of an organic moiety onto an electrode surface through the formation of radical species with concomitant electron transfer to or from molecules containing suitable activating groups, such as diazoniums or iodoniums (Figure c) . This process affords an organic coating with strong adhesion to many conductive substrates, such as Cu, Ag, glassy carbon, and stainless steel, that can withstand sonication even in organic solvents and could therefore be a promising alternative strategy to prolong catalytic performance. − Unfortunately, reports using ethynyl and azide aryl radical precursors on copper surfaces have shown little promise for achieving significant enhancement of CO 2 R selectivity, likely due to the conflation of effects from the highly functionalized film and the anodic grafting mechanism employed. Alternative methods that allow a decoupling of the effects of deposition techniques and film functionalization are therefore desirable to obtain a greater understanding of the mechanism by which grafted films affect selectivity.…”

Rational Design of Metal–Organic Frameworks for Electroreduction of CO2 to Hydrocarbons and Carbon Oxygenates

“…To date, the highest Faradaic efficiency (FE) for yielding CH 4 , C 2 H 4 , and C 2+ products based on MOF electrocatalysts reaches >80%, ,, >50%, ,, and 80%, respectively (Figure and Table ). Previous reports revealed that the electrocatalysts with Au, , Ag, Co, − or Ni − active sites tend to generate CO as the main product, and those with In , or Sn , result in formate. Since the copper center has a negative adsorption energy for an essential intermediate *CO and a positive adsorption energy for *H, , Cu-based catalysts show an enormous advantage in electrochemical reduction of CO 2 to the high value-added products, such as hydrocarbons and carbon oxygenates ( i .…”

Advancing integrated CO2 electrochemical conversion with amine-based CO2 capture: a review

“…[5][6][7] However, the state-of-the-art CO 2 electrolysis usually uses pure CO 2 as the feed, while CO 2 is diluted in most industrial sources (<20% for flue gases from blast furnaces and post-combustion power plants [8][9][10] ). 5,[11][12][13][14][15][16][17][18][19][20][21] When implemented in practice, CO 2 electrolysis requires costly upstream CO 2 capture processes 22,23 to concentrate CO 2 , and an energy-intensive product separation process 24,25 to recycle CO 2 and concentrate product streams. In addition, gaseous CO 2 reacts with hydroxide ions generated within CO 2 electroreduction systems to form (bi)carbonate.…”