The spatial distribution of cobalt phthalocyanine and copper nanocubes controls the selectivity towards C 2 products in tandem electrocatalytic CO 2 reduction

The coupling of CO-generating molecular catalysts with copper electrodes in tandem schemes is a promising strategy to boost the formation of multi-carbon products in the electrocatalytic reduction of CO2. While the spatial distribution of the two components is important, this aspect remains underexplored for molecular-based tandem systems. Herein, we address this knowledge gap by studying tandem catalysts comprising Co-phthalocyanine (CoPc) and Cu nanocubes (Cucub). In particular, we identify the importance of the relative spatial distribution of the two components on the performance of the tandem catalyst by preparing CoPc-Cucub/C, wherein the CoPc and Cucub share an interface, and CoPc-C/Cucub, wherein the CoPc is loaded first on carbon black (C) before mixing with the Cucub. The electrocatalytic measurements of these two catalysts show that the faradaic efficiency towards C2 products almost doubles for the CoPc-Cucub/C, whereas it decreases by half for the CoPc-C/Cucub, compared to the Cucub/C. Our results highlight the importance of a direct contact between the CO-generating molecular catalyst and the Cu to promote C-C coupling, which hints at a surface transport mechanism of the CO intermediate between the two components of the tandem catalyst instead of a transfer via CO diffusion in the electrolyte followed by re-adsorption

Composition effects of electrodeposited Cu-Ag nanostructured electrocatalysts for CO2 reduction

The electrochemical reduction of carbon dioxide (CO2RR) to valuable C2+ liquid fuels and oxygenates, such as ethanol and propanol, is a promising strategy to minimize the carbon footprint and store renewable electricity. In this study, we investigate the CO2RR on electrodeposited Cu-Ag nanostructures obtained using a green choline chloride and urea deep eutectic solvent (DES). We show that Cu-Ag nanostructured electrocatalysts with tunable composition, loadings, and size can be simply prepared in one step, without adding other additives or surfactant agents. We investigate the intrinsic activity and selectivity of the CO2RR by determining the electrochemically active surface area (ECSA) using lead underpotential deposition (UPD). The analysis of the partial current densities normalized by the ECSA shows that the addition of Ag on electrodeposited Cu primarily suppresses the production of hydrogen and methane with respect to Cu nanostructures. At the same time, the production of carbon monoxide (CO) slightly increases but, the partial current of the total C2+ products does not considerably increase. Despite that the production rate of C2+ is similar on Cu and CuAg, the addition of Ag enhances the formation of alcohols and oxygenates over ethylene, in line with previous reports. We highlight the potential of metal electrodeposition from DES as a sustainable and inexpensive strategy for the development of bimetallic Cu-based nanocatalysts towards CO2RR

Composition effects of electrodeposited Cu-Ag nanostructured electrocatalysts for CO₂ reduction

The electrochemical carbon dioxide reduction (CO2RR) on Cu-based catalysts is a promising strategy to store renewable electricity and produce valuable C2+ chemicals. We investigate the CO2RR on Cu-Ag nanostructures that have been electrodeposited in a green choline chloride and urea deep eutectic solvent (DES). We determine the electrochemically active surface area (ECSA) using lead underpotential deposition (UPD) to investigate the CO2RR intrinsic activity and selectivity. We show that the addition of Ag on electrodeposited Cu primarily suppresses the production of hydrogen and methane. While the production of carbon monoxide slightly increases, the partial current of the total C2+ products does not considerably increase. Despite that the production rate of C2+ is similar on Cu and Cu-Ag, the addition of Ag enhances the formation of alcohols and oxygenates over ethylene. We highlight the potential of metal electrodeposition from DES as a sustainable strategy to develop bimetallic Cu-based nanocatalysts for CO2RR.</p

Colloidal Nanocrystals as Electrocatalysts with Tunable Activity and Selectivity

Correlating the catalyst activity, selectivity, and stability with its structure and composition is of the utmost importance in advancing the knowledge of heterogeneous electrocatalytic processes for chemical energy conversion. Well-defined colloidal nanocrystals with tunable monodisperse size and uniform shapes are ideal platforms to investigate the effect of these parameters on the catalytic performance. In addition to translating the knowledge from single-crystal studies to more realistic conditions, the morphological and compositional complexity attainable by colloidal chemistry can provide access to active catalysts which cannot be produced by other synthetic approaches. The sample uniformity is also beneficial to investigate catalyst reconstruction processes via both ex situ and operando techniques. Finally, colloidal nanocrystals are obtained as inks, a feature which facilitates their integration on different substrates and cell configurations to study the impact of interactions at the mesoscale and the device-dependent reaction microenvironment on the catalytic outcome. In this Review, we discuss recent studies in selected electrochemical reactions and provide our outlook on future developments on the use of well-defined colloidal nanocrystals as an emerging class of electrocatalysts