Morphology and mechanism of highly selective Cu(II) oxide nanosheet catalysts for carbon dioxide electroreduction

Abstract

Cu oxides catalyze the electrochemical carbon dioxide reduction reaction (CO2RR) to hydrocarbons and oxygenates with favorable selectivity. Among them, the shape-controlled Cu oxide cubes have been most widely studied. In contrast, we report on novel 2-dimensional (2D) Cu(II) oxide nanosheet (CuO NS) catalysts with high C2+ products, selectivities (> 400 mA cm−2) in gas diffusion electrodes (GDE) at industrially relevant currents and neutral pH. Under applied bias, the (001)-orientated CuO NS slowly evolve into highly branched, metallic Cu0 dendrites that appear as a general dominant morphology under electrolyte flow conditions, as attested by operando X-ray absorption spectroscopy and in situ electrochemical transmission electron microscopy (TEM). Millisecond-resolved differential electrochemical mass spectrometry (DEMS) track a previously unavailable set of product onset potentials. While the close mechanistic relation between CO and C2H4 was thereby confirmed, the DEMS data help uncover an unexpected mechanistic link between CH4 and ethanol. We demonstrate evidence that adsorbed methyl species, *CH3, serve as common intermediates of both CH3H and CH3CH2OH and possibly of other CH3-R products via a previously overlooked pathway at (110) steps adjacent to (100) terraces at larger overpotentials. Our mechanistic conclusions challenge and refine our current mechanistic understanding of the CO2 electrolysis on Cu catalysts.

A Water-Soluble Sodium Pectate Complex with Copper as an Electrochemical Catalyst for Carbon Dioxide Reduction

“…It should be noted that the immobilization of water-soluble complexes on carbon nanotubes or graphene makes it possible to increase the current density, but it cannot be attributed to the homogeneous catalysis. CO 2 RR catalysts based on metallic copper and copper oxides can exhibit much higher catalytic activity with a current density in the range of 100–400 mA/cm 2 [ 25 , 34 ]. Having discovered such intriguing properties of the complex, we decided to study it in more detail.…”

“…The reduction of copper complexes can sometimes lead to the electrodeposition of metallic Cu (0) or copper oxides on electrodes [ 43 ]. There are many examples of both molecular copper catalysts for the CO 2 reduction [ 44 , 45 , 46 ] and CO 2 reduction catalysts based on metallic copper or copper oxides [ 25 , 26 , 27 ]. We assert that in the case of the PG-NaCu complex and at potentials more positive than −1.5 V (vs. Ag/AgCl), there is no deposition of copper or copper oxide on the glassy carbon electrode.…”

“…It is well known that copper electrodes, as well as nanostructured copper and copper oxides, promote the electrocatalytic conversion of CO 2 to deep reduced products such as methane, ethylene, and ethanol [ 1 , 25 , 26 , 27 ]. However, there are a number of examples of the electrocatalytic conversion of CO 2 to CH 4 , C 2 H 4 , C 2 O 4 on single copper ions [ 28 , 29 , 30 , 31 , 32 ].…”

Seeing is believing: In-situ visualising dynamic evolution in CO2 electrolysis

“…In-situ liquid transmission electron microscopy (TEM) was used by the Strasser group to track realtime morphology transformation of CuO nanosheet during CO2RR. [22] As shown in Figure 1a, at the beginning stage, the pristine CuO nanosheet was observed to undergo fragmentation to smaller sheet without disintegration, then convert to spherical, and finally reassemble to stable, larger branched dendritic Cu structures. This in-situ recorded information demonstrates that Cu catalysts kinetically prefer to form dendritic morphology under electrolyte-flowing conditions.…”

Human Embryos, Induced Pluripotent Stem Cells, and Organoids: Models to Assess the Effects of Environmental Plastic Pollution

“…Henson et al (2019) examined the cytotoxicity of cupric (II) oxide (CuO) and Cu 2 O-polyvinylpyrrolidone (PVP)coated Nps and copper ions on rat intestine epithelial cells (IEC-6) and human intestinal cells, 2D and 3D models. The mechanism by which copper nanoparticles cause toxicological properties includes reactive oxygen species (ROS) forming, reduction of cellular glutathione, mitochondrial membrane depolarization (Thit et al, 2015;Wang et al, 2021), mitochondrial membrane damage (Wang Y et al, 2012;Wang Z et al, 2012), and the release of toxic Cu ions (Fröhlich, 2013). In line with these outcomes, Henson et al (2019) (Markus et al, 2021).…”