Surface Adsorbed Hydroxyl: A Double‐Edged Sword in Electrochemical CO₂ Reduction over Oxide‐Derived Copper

Abstract

Oxide-derived Cu (ODÀ Cu) featured with surface located sub-20 nm nanoparticles (NPs) created via surface structure reconstruction was developed for electrochemical CO 2 reduction (ECO 2 RR). With surface adsorbed hydroxyls (OH ad ) identified during ECO 2 RR, it is realized that OH ad , sterically confined and adsorbed at ODÀ Cu by surface located sub-20 nm NPs, should be determinative to the multi-carbon (C 2 ) product selectivity. In situ spectral investigations and theoretical calculations reveal that OH ad favors the adsorption of lowfrequency *CO with weak C�O bonds and strengthens the *CO binding at ODÀ Cu surface, promoting *CO dimerization and then selective C 2 production. However, excessive OH ad would inhibit selective C 2 production by occupying active sites and facilitating competitive H 2 evolution. In a flow cell, stable C 2 production with high selectivity of ~60 % at À 200 mA cm À 2 could be achieved over ODÀ Cu, with adsorption of OH ad well steered in the fast flowing electrolyte.

Crucial Effect of Surface Oxygen Species on CO2 Electroreduction Performance in Ti@Cu Single Atom Alloys

“…For the change in eCO2RR selectivity of different oxides on the surface, we combine this with related studies to suggest that this phenomenon is attributable to differences in surface HER properties. [33] As shown in Figure S38, *H on the O-Ti surface has a high barrier to form H2 (ΔG = 0.67 eV), which makes it difficult to form H2, and therefore easy *H is readily added to the intermediate to form oxygen-free alkanes. *H on the OH-Ti@Cu surface is very easy to form H2 (ΔG = 0.17 eV).…”

“…[32] Wei et al found that Cu NPs adsorb *OH on their surfaces during eCO2RR and that a small amount of adsorbed *OH promotes C-C coupling, but a large amount of *OH promotes HER. [33] Akbar et al found that hydroxyl groups on the Au/TiO2 surface can have an effect on hydrogen overflow. [34] These adsorbed oxygen species have two potential outcomes: (1) Be reduced through oxygen reduction reactions; (2) Keep stable under specific potentials.…”

Phosphate-Derived Copper-Based Catalysts for Efficient CO2 Reduction to Multicarbon Products

“…The carbon dioxide electrocatalytic reduction reaction (CO 2 ERR), which holds promise for producing value-added fuels or chemicals from anthropogenically emitted CO 2 using renewable electricity, has received considerable attention as a promising strategy to mitigate global warming and to store the intermittent sustainable energy. − Although significant efforts have been dedicated to develop efficient CO 2 ERR catalysts, the high CO 2 activation energy barrier and the complex multiple proton/electron-coupled reaction processes lead to formidable challenges for improving both the activity and selectivity toward desirable products. , …”

“…Cu is by far the most promising CO 2 ERR catalyst for its unique moderate *CO binding capacity to produce multicarbon chemicals, which can alleviate the severe dependence of energy and chemical industries on fossil fuels. − A variety of Cu-based CO 2 ERR catalysts have been developed, such as Cu-based nanoparticles, − metal oxides, − metal–organic frameworks, − etc. Among them, oxide-derived Cu (OD-Cu) catalysts obtained via thermo- or electroreduction of Cu 2 O/CuO precursors often show significantly improved CO 2 ERR performance to achieve high C 2+ product selectivity compared to metallic Cu. , Despite some work for OD-Cu catalysts only elevating the CO 2 ERR activity toward C 1 production, − Kas et al first reported a 32.5% C 2+ faradaic efficiency at 15 mA cm –2 over Cu 2 O-derived Cu, with the relevance of the parent Cu 2 O film thickness with the C 2+ selectivity .…”

Halide precursor reduction strategy to modulate bismuthene with high selectivity and wide potential window for electrochemicalCO2reduction

“…generated products are diverse and selective, [12][13][14][15][16][17][18][19][20] including CO, CH 4 , HCOOH or HCOO À (formate), CH 3 OH, C 2 H 4 , CH 3 CH 2 OH and n-C 3 H 7 OH, depending on the electrocatalysts and electrolytes. [21][22][23][24] Based on techno-economic analysis, HCOOH/HCOO À is a typical C 1 molecule that has a high net present value and a large commercial value of up to $0.50/kg, 25 and is widely used in the chemical and pharmaceutical industries in large quantities.…”