Surface Energy Tuning on Cu/NC Catalysts for CO Electroreduction

Abstract

Electrochemical CO reduction reaction (CORR) represents a potential approach to generate value-added products. Nonetheless, it is generally challenging for conventional measurements to quantify the catalytic surface properties, due to the geometric blockage and synergistic effect from the support. Herein, the surface energy of copper-loaded nitrogen-doped carbon (Cu/NC) was investigated by adsorption with specific functional groups using inverse gas chromatography (IGC). The dispersive component (γS D) and the acid/base character of the surface energy were determined using non-polar and polar probe molecules. The specific free energy (ΔG AB), the enthalpy of adsorption (ΔH AB), and the acidic (K A) and basic (K D) parameters were obtained, which allowed to provide the affinity information of intermediates such as *CHO, *OCH2COH, and *H. The surface energy analysis suggested that the Cu/N0.17C catalyst with the highest basic parameter (K D = 7.350) and optimal acid interaction (K A/K D ∼ 0.046) exhibited high catalytic performance in the acetate production, with a Faradaic efficiency (FE) of 63% and a partial current density of −330 mA·cm–2. The exposed catalytic sites on Cu/NC were suggested to activate H2O and stabilize oxygenate intermediates favorably for the electrochemical CO-to-acetate conversion.

Tuning Structures and Microenvironments of Cu-Based Catalysts for Sustainable CO2 and CO Electroreduction

“…For instance, Sargent and coworkers reported a polymer-based gas diffusion electrode with an abrupt interface between Cu catalyst, graphite, and porous polytetrafluoroethylene, 51 achieving an efficient CO 2 -to-C 2 H 4 conversion (FE ∼ 70%) and a high CO 2 RR durability of 150 h in 7 M KOH. Another recent study 34 by Liu et al based on Cu catalyst loaded on different nitrogen-doped carbon supports (with different atomic ratios of N in those supports) demonstrated that surface energy (or local acid−base property) also plays a significant role in CORR. The surface energy analysis suggested that the Cu/N 0.17 C catalyst with the highest basic parameter (K D = 7.350, Figure 4B) and optimal acid interaction (K A /K D ∼ 0.046, Figure 4C) exhibited the best catalytic performance in the CO-to-acetate conversion, and a FE of 63% was obtained at a partial current density of −330 mA•cm −2 (Figure 4D).…”

“…(D) Faradaic efficiencies of C 1 and C 2+ at around −1.02 V vs RHE and corresponding ratios of C 2+ to C 1 products. Reproduced with permission from ref . Copyright 2022 American Chemical Society.…”

“…The alloying effect (e.g., electron transfer or the increased density of phase boundaries) has been employed in the fabrication of tandem catalysts . In addition, surface environment tuning (e.g., type of support, local pH, hydrophobicity) has also been investigated to enhance catalytic reactivity. ,− …”

g-C3N4 Nanosheet Supported CuO Nanocomposites for the Electrochemical Carbon Dioxide Reduction Reaction

“…The nature of the catalyst support can also influence product selectivity. Recent studies suggest that N-doped carbon supports can stabilize Cu in a Cu–N coordination environment during electrolysis and shows the product selectivity toward ethanol or other C2 products. − Cu on N-doped carbon has also been used in thermal catalysis and shows enhanced stability, and there are reports utilizing N-doped carbon as a catalyst support for electrocatalysis. − A theoretical study of Cu dimer on C 2 N predicts a favored product of C 2 H 4 . We hypothesize that the N-doped carbon support for CO 2 RR will stabilize the intermediate states of CO 2 adsorbates and the catalysts, which leads to specific CO 2 RR products, owing to the coordination between the N and the d-orbitals of the metal atoms.…”

“… 30 − 36 Cu on N-doped carbon has also been used in thermal catalysis and shows enhanced stability, 37 and there are reports utilizing N-doped carbon as a catalyst support for electrocatalysis. 38 − 47 A theoretical study of Cu dimer on C 2 N predicts a favored product of C 2 H 4 . 48 We hypothesize that the N-doped carbon support for CO 2 RR will stabilize the intermediate states of CO 2 adsorbates and the catalysts, which leads to specific CO 2 RR products, owing to the coordination between the N and the d-orbitals of the metal atoms.…”