Stabilizing Cu²⁺ Ions by Solid Solutions to Promote CO₂ Electroreduction to Methane

Abstract

Copper is the only metal catalyst that can perform the electrocatalytic CO 2 reduction reaction (CRR) to produce hydrocarbons and oxygenates. Its surface oxidation state determines the reaction pathway to various products. However, under the cathodic potential of CRR conditions, the chemical composition of most Cu-based catalysts inevitably undergoes electroreduction from Cu 2+ to Cu 0 or Cu 1+ species, which is generally coupled with phase reconstruction and the formation of new active sites. Since the initial Cu 2+ active sites are hard to retain, there have been few studies about Cu 2+ catalysts for CRR. Herein we propose a solidsolution strategy to stabilize Cu 2+ ions by incorporating them into a CeO 2 matrix, which works as a self-sacrificing ingredient to protect Cu 2+ active species. In situ spectroscopic characterization and density functional theory calculations reveal that compared with the conventionally derived Cu catalysts with Cu 0 or Cu 1+ active sites, the Cu 2+ species in the solid solution (Cu-Ce-O x ) can significantly strengthen adsorption of the *CO intermediate, facilitating its further hydrogenation to produce CH 4 instead of dimerization to give C 2 products. As a result, different from most of the other Cu-based catalysts, Cu-Ce-O x delivered a high Faradaic efficiency of 67.8% for CH 4 and a low value of 3.6% for C 2 H 4 .

The presence and role of the intermediary CO reservoir in heterogeneous electroreduction of CO 2

“…The 12 C fraction of CH4 is consistent with all other COint-derived products which corroborates the importance of CO as an intermediate for CH4 production during CO2 electroreduction. 15,56 However, a collection of gases (i.e., CO, CH4, and C2H4) was detected when trying to identify the contents of the reservoir experimentally as described in Fig. 1c (Supplementary Text 10 and Fig.…”

Customizing the microenvironment of CO2 electrocatalysis via three‐phase interface engineering

“…Consequently, researchers focus on the development of various catalysts with high activity. [9][10][11] Similarly, substantial efforts have been invested in the fabrication of different CRR catalysts, including single-atom, 12 alloy, 13,14 surface oxidation state, [15][16][17] grain boundaries, 18 solid solutions, 19 morphologies, 20,21 chemical composition, 22 and crystal facet engineering. 23 Nevertheless, differently to thermal catalysis, since CRR occurs on a gas/solid/liquid three-phase interface (Figure 1C), 24 its reactivity is also sensitive to the local reaction environment of the catalysts, such as the specific electrolyte, 25 pH, 26 presence of metal cations, 27 surface structure and composition of the catalyst, 28 and some other factors.…”

Surface Modification of 2D Photocatalysts for Solar Energy Conversion

“…Recently, photocatalytic CO 2 conversion to valuable chemical fuels or raw has aroused extensive research attention. [177][178][179][180][181] However, CO 2 molecule has a pretty stable structure and requires high dissociation energy (750 kJ mol −1 ) to cleave the CO bond. Therefore, the demand for input energy in the photocatalytic CO 2 reduction process is much higher than hydrogen production from water splitting.…”