Sequential Cascade Electrocatalytic Conversion of Carbon Dioxide to C–C Coupled Products

Abstract

Cascade catalytic processes perform multi-step chemical transformations without isolating the intermediates. Here, we demonstrate a sequential cascade pathway to convert CO 2 to C 2+ hydrocarbons and oxygenates in a two-step electrocatalytic process using CO as the intermediate. CO 2 to CO conversion is performed by using Ag and further conversion of CO to CC coupled products is performed with Cu. Temporal separation between the two reaction steps is accomplished by situating the Ag electrode upstream of the Cu electrode in a continuous flow reactor. Convection-diffusion simulations and experimental evaluation of the electrodes individually were performed to identify optimal conditions. With the upstream Ag electrode poised at-1 V vs RHE in a flow of CO 2-saturated water in aqueous carbonate buffer, over 80% of the CO can be converted on the downstream Cu electrode. When the Ag electrode is on, a supersaturation of CO is achieved near the Cu electrode, which leads to a relative increase in the formation rate of C 2 and C 3 oxygenates as compared to ethylene.

Electrocatalysis as the Nexus for Sustainable Renewable Energy: The Gordian Knot of Activity, Stability, and Selectivity

“…In flow electrochemical reactors, active sites are spatially separated so that a product formed upstream is transported to downstream active sites by convection. [63] We give a brief overview on high-entropy alloys (HEAs), nanozymes, and nanocavities by design, as emergent catalyst design concepts that facilitate cascaded electrocatalysis to achieve unprecedented selectivity of desired products.…”

“…In cascaded electrocatalysis, the active sites of an electrocatalyst are spatially arranged in a such a way that an intermediate or product generated during a specific electrochemical step at one of the active sites is subsequently converted at the adjacent active site through either surface diffusion, forced convection, or confinement. In flow electrochemical reactors, active sites are spatially separated so that a product formed upstream is transported to downstream active sites by convection . We give a brief overview on high‐entropy alloys (HEAs), nanozymes, and nanocavities by design, as emergent catalyst design concepts that facilitate cascaded electrocatalysis to achieve unprecedented selectivity of desired products.…”

Pulsed Electrochemical Carbon Monoxide Reduction on Oxide‐Derived Copper Catalyst

“…Thus, a promising approach to mitigate the limitations of the CO 2 RR scaling relations is the further direct electrochemical reduction of CO in a second electrocatalytic system. Cascade electrolysis systems have been demonstrated by first reducing CO 2 to CO with Au or Ag, then subsequently flowing the CO to a second electrolyzer or catalyst for a more selective secondary reduction . With OD‐Cu, for instance, the grain boundary active sites promote adjacent CO binding and subsequent C−C bond formation, leading to higher FE for C 2 products such as ethanol and acetate compared to conventional Cu for the electrochemical CO reduction reaction (CORR) .…”

Elektrokatalyse als Nexus für nachhaltige erneuerbare Energien – der gordische Knoten aus Aktivität, Stabilität und Selektivität

“…In elektrochemischen Strçmungsreaktoren sind die aktiven Zentren räumlich getrennt, sodass ein zuerst gebildetes Produkt durch Konvektion zu den folgenden aktiven Zentren transportiert wird. [63] Wir geben einen kurzen Überblick über das Design von Hochentropielegierungen (HEA), Nanozymen und Nanokavitäten als aktuelle Konzepte des Katalysatordesigns, die elektrokatalytische Kaskadenreaktionen erleichtern, um eine beispiellose Selektivität für gewünschten Produkte zu erreichen.…”

“…Bei der elektrokatalytischen Kaskadenreaktion werden die aktiven Zentren eines Elektrokatalysators räumlich so angeordnet, dass ein Zwischenprodukt oder ein Produkt, das während eines bestimmten elektrochemischen Schritts an einem der aktiven Zentren erzeugt wird, an den benachbarten aktiven Zentren durch Oberflächendiffusion, erzwungene Konvektion oder Einschluss sequenziell umgewandelt wird. In elektrochemischen Strömungsreaktoren sind die aktiven Zentren räumlich getrennt, sodass ein zuerst gebildetes Produkt durch Konvektion zu den folgenden aktiven Zentren transportiert wird . Wir geben einen kurzen Überblick über das Design von Hochentropielegierungen (HEA), Nanozymen und Nanokavitäten als aktuelle Konzepte des Katalysatordesigns, die elektrokatalytische Kaskadenreaktionen erleichtern, um eine beispiellose Selektivität für gewünschten Produkte zu erreichen.…”