Bio-inspired hydrophobicity promotes CO2 reduction on a Cu surface

Abstract

Aqueous electrocatalytic reduction of CO 2 into alcohol and hydrocarbon fuels presents a sustainable route towards energy-rich chemical feedstocks. Cu is the only material able to catalyse the substantial formation of multi-carbon products (C 2 /C 3), however competing proton reduction to hydrogen is an ever-present drain on selectivity. Herein, a superhydrophobic surface was generated by 1-octadecanethiol treatment of hierarchically structured Cu dendrites, inspired by the structure of gas-trapping cuticles on subaquatic spiders. The hydrophobic electrode attained 56% Faradaic efficiency for ethylene and 17% for ethanol production at neutral pH, compared to 9% and 4% on a hydrophilic, wettable equivalent. These observations are assigned to trapped gases at the hydrophobic Cu surface, which increase the concentration of CO 2 at the electrode|solution interface and consequently increase CO 2 reduction selectivity. Hydrophobicity is thus proposed as a governing factor in CO 2 reduction selectivity and can help explain trends seen on previously reported electrocatalysts.

Accelerating CO2 Electroreduction to CO Over Pd Single‐Atom Catalyst

“…[ 6–8 ] To date, many efforts have been made to achieve the production of C 1 C 3 products from CO 2 RR. [ 9–14 ] It has also been reported that C 1 products, such as carbon monoxide (CO) and formate, typically show sufficiently high activity and selectivity. [ 15–19 ] Moreover, the energy efficiencies of C 1 products should be higher than that of C 2 + products based on its mechanistic simplicity.…”

Recent Progress in Self‐Supported Catalysts for CO2 Electrochemical Reduction

“…In order to develop efficient and highly selective catalysts, a large number of self‐supporting metal dendritic nanoarrays have been developed, including transition metals (such as Au, Ag, Cu, Bi, and Zn) and their composites. The electrodeposited Cu dendrites mainly brought forth multielectron products, including C 2 H 4 67,68,72,77 and CH 3 CHO 76. Especially, this kind of CO 2 RR electrocatalysts could even generate a remarkable ≈170 mA cm −2 current density, which might meet the commercial standard.…”

“…Moreover, the electric field can drive almost all chemical reactions, which could be utilized as an effective method to produce the desired compounds in a controlled manner. Table 3 displays the summary of the electrodeposited metal nanodendrites as efficient CO 2 RR electrocatalysts,66–77 including, electrolyte, main product, cathode potential, current density, and Faradaic efficiency. Up till now, electrochemical deposition has been frequently adopted to prepare all kinds of self‐supported metal nanodendrite arrays as CO 2 RR electrocatalysts.…”

“…The hydrophobic surfaces allow gaseous CO 2 to reach the three‐phase interface, which effectively promotes gas capture and enhances carbon CO 2 reduction. In this direction, Mougel and co‐workers developed a super‐hydrophobic Cu dendrite electrode via the treatment of hierarchically structured Cu dendrites in 1‐octadecanethiol 68. The electrochemically active surface area of super‐hydrophobic Cu dendrites was much lower than the wettable dendrite, although the geometric surface area of the wettable dendrite and super‐hydrophobic Cu dendrite remained similar.…”

An Artificial Electrode/Electrolyte Interface for CO2 Electroreduction by Cation Surfactant Self‐Assembly

“…[9] Electron and mass transfer at this interface are crucial to the electrochemical CO 2 reduction process.P revious report revealed that larger alkali cations could alter the local electric properties of electrode surface thus tuning the selectivity for CO,C 2 H 4 ,a nd C 2 H 5 OH, [10] while small organic molecule coating on the electrode surface could alter the adsorption and diffusion behaviors of CO 2 . [11] Inspired by these previous reports,h erein, we developed an artificial E/E interface enabled by quaternary ammonium cation surfactants (Figure 1). In our study,aCu-nanowire (Cu NW) electrocatalyst was used as an example to demonstrate this interface design since it has multiple reaction routes and reduction products for CO 2 RR with selectivity towards various C 1 and C 2+ products,a sw ell as the competing hydrogen evolution.…”