Nanostructured Copper-Based Electrodes Electrochemically Synthesized on a Carbonaceous Gas Diffusion Membrane with Catalytic Activity for the Electroreduction of CO₂

Abstract

In this work, four different 4 cm2-sized nanostructured Cu-based electrocatalysts have been designed by a one-step electrodeposition process of Cu metal on a three-dimensional carbonaceous membrane. One consisted of Cu0, and the other three were obtained by further simple oxidative treatments. Morphological, structural, and electrochemical investigations on the four materials were carried out by scanning electron microscopy, Raman spectroscopy, X-ray diffraction, linear sweep voltammetry, and potential-controlled electrolysis. All the electrocatalysts showed promising catalytic activities toward CO2 electroreduction in liquid phase, with a remarkable selectivity toward acetic acid achieved when using the oxidized materials. In particular, the best electrocatalytic activity was observed for the Cu2O-Cu0 catalyst, working at a relatively low potential (−0.4 V vs RHE), which exhibited a stable and low current density of 0.46 mA cm–2 and a productivity of 308 μmol gcat –1 h–1. These results were attributed to the nanostructured morphology that is characterized by many void spaces and by a high surface area, which should guarantee a large number of CuI and Cu0 catalytic active sites. Moreover, kinetic analyses and preliminary studies about catalyst regeneration highlighted the stability of the best-performing catalyst.

Electrosynthesized CuMgAl Layered Double Hydroxides as New Catalysts for the Electrochemical Reduction of CO2

“…[16,[39][40][41][42][43] On the other hand, although the reaction mechanism is still under debate, many research groups have recently proved that catalysts containing adjacent Cu 0 and Cu I sites are mainly capable to activate the CO 2 reduction and the CC coupling. [17,[44][45][46][47] However, while the production of two electrons-transfer compounds like CO or HCOOH has already reached FE close to 100%, [48] ≥ C 2 compounds are generally produced at relatively high potentials resulting in prohibitively high efficiency losses and low FE. [49] Interestingly, it has been recently demonstrated the ability of nanostructured Cu-based electrocatalysts (containing Cu 0 and Cu 2 O species), loaded on carbonaceous supports, to drive the reaction toward the production of CH 3 COOH in liquid phase configuration combining low overpotential with high selectivity.…”

“…[49] Interestingly, it has been recently demonstrated the ability of nanostructured Cu-based electrocatalysts (containing Cu 0 and Cu 2 O species), loaded on carbonaceous supports, to drive the reaction toward the production of CH 3 COOH in liquid phase configuration combining low overpotential with high selectivity. [17,40,50] The production of acetic acid is of particular interest from an industrial point of view due to its wide applicability in many chemical sectors. [51] Up to now, the request of acetic acid is fulfilled by industrial multistep fermentative and chemical processes.…”

“…[41,86,87] This unprecedented result demonstrates the beneficial effects of a composite combining the layered double hydroxide structure with highly dispersed copper species, which allows to obtain (i) a C 2 product at a low potential applied during CO 2 ER, (ii) a selectivity close to 100% as to the CO 2 reduction products, since only H 2 as side product was detected in the gaseous phase, and (iii) an enhanced productivity compared to the nanostructured Cu 0 /Cu 2 O films investigated in our previous work. [17]…”

“…[3,7] The conversion of the carbon dioxide can be achieved through different approaches, which involve biochemical, [8,9] radiochemical, [10] thermochemical, [11][12][13] photochemical, [14,15] or electrochemical reactions. [16,17] Among these, the electrocatalytic reduction is particularly attractive by virtue of its mild operative conditions, its easily customized reaction outcomes, and its great potential toward scale up. [18][19][20] In addition, the electrons required for the activation of the CO 2 molecule can be directly gained from renewable sources, ensuring an eco-friendly alternative and setting the scene toward the fascinating concept of the solar light-driven chemistry.…”

“…[18][19][20] In addition, the electrons required for the activation of the CO 2 molecule can be directly gained from renewable sources, ensuring an eco-friendly alternative and setting the scene toward the fascinating concept of the solar light-driven chemistry. [17,[21][22][23] However, to seize all the benefits that the electrochemical approach can provide and to make it affordable from an industrial point of view, [24] the design of the electrocatalyst plays a key role. To date, strong push has been given to the utilization of sustainable materials, which find their best candidates in the carbon-based electrodes.…”