Efficient CO2 electroreduction on tin modified cuprous oxide synthesized via a one-pot microwave-assisted route

Bimetallic copper-tin catalysts are considered cost-effective and suitable for large-scale electrochemical conversion of CO2 to valuable products. In this work, a class of tin (Sn) modified cuprous oxide (Cu2O) is simply synthesized through a one-pot microwave-assisted solvothermal method and thoroughly characterized by various techniques. Sn is uniformly distributed on the Cu2O crystals showing a cube-within-cube structure, and CuSn alloy phase emerges at high Sn contents. The atomic ratio of Cu to Sn is found to be crucially important for the selectivity of the CO2 reduction reaction, and a ratio of 11.6 leads to the optimal selectivity for CO. This electrode shows a high current density of 47.2 mA cm−2 for CO formation at −1.0 V vs. the reversible hydrogen electrode and also displays good CO selectivity of 80–90% in a wide potential range. In particular, considerable CO selectivity of 72–81% is achieved at relatively low overpotentials from 240 mV to 340 mV. During the long-term tests, satisfactory stability is observed for the optimal electrode in terms of both electrode activity and CO selectivity. The relatively low price, the fast and scalable synthesis, and the encouraging performance of the proposed material implies its good potential to be implemented in large-scale CO2 electrolyzers

Biochar/Zinc Oxide Composites as Effective Catalysts for Electrochemical CO2 Reduction

Novel electrocatalysts based on zinc oxide (ZnO) and biochars are prepared through a simple and scalable route and are proposed for the electrocatalytic reduction of CO2 (CO2RR). Materials with different weight ratios of ZnO to biochars, namely, pyrolyzed chitosan (CTO) and pyrolyzed brewed waste coffee (CBC), are synthesized and thoroughly characterized. The physicochemical properties of the materials are correlated with the CO2RR to CO performance in a comprehensive study. Both the type and weight percentage of biochar significantly influence the catalytic performance of the composite. CTO, which has pyridinic- and pyridone-N species in its structure, outperforms CBC as a carbon matrix for ZnO particles, as evidenced by a higher CO selectivity and an enhanced current density at the ZnO_CTO electrode under the same conditions. The study on various ZnO to CTO weight ratios shows that the composite with 40.6 wt % of biochar shows the best performance, with the CO selectivity peaked at 85.8% at -1.1 V versus the reversible hydrogen electrode (RHE) and a CO partial current density of 75.6 mA cm-2 at -1.3 V versus RHE. It also demonstrates good stability during the long-term CO2 electrolysis, showing high retention in both CO selectivity and electrode activity

Facile synthesis of cubic cuprous oxide for electrochemical reduction of carbon dioxide

Abstract: High level of atmospheric carbon dioxide (CO2) concentration is considered one of the main causes of global warming. Electrochemical conversion of CO2 into valuable chemicals and fuels has promising potential to be implemented into practical and sustainable devices. In order to efficiently realize this strategy, one of the biggest efforts has been focused on the design of catalysts which are inexpensive, active and selective and can be produced through green and up-scalable routes. In this work, copper-based materials are simply synthesized via microwave-assisted process and carefully characterized by physical/chemical/electrochemical techniques. Nanoparticle with a cupric oxide (CuO) surface as well as various cuprous oxide (Cu2O) cubes with different sizes is obtained and used for the CO2 reduction reaction. It is observed that the Cu2O-derived electrodes show enhanced activity and carbon monoxide (CO) selectivity compared to the CuO-derived one. Among various Cu2O catalysts, the one with the smallest cubes leads to the best CO selectivity of the electrode, attributed to a higher electrochemically active surface area. Under applied potentials, all Cu2O cubes undergo structural and morphological modification, even though the cubic shape is retained. The nanoclusters formed during the material evolution offer abundant and active reaction sites, leading to the high performance of the Cu2O-derived electrodes

Correlation between impedance spectroscopy and bubble-induced mass transport in the electrochemical reduction of carbon dioxide

In the electrochemical conversion of carbon dioxide, high currents need to be employed to obtain large production rates, thus implying that mass transport of reactants and products is of crucial importance. This aspect can be investigated by employing a model that depicts the local environment for the reduction reactions. Simultaneously, electrochemical impedance spectroscopy, despite being a versatile technique, has rarely been adopted for studying the mass transport features during the carbon dioxide (CO2) electroreduction. In this work, this aspect is deeply analyzed by correlating the results of impedance spectroscopy characterization with those obtained by a bubble-induced mass transport modeling under controlled diffusion conditions on a gold rotating disk electrode. The effects of potential and rotation rate on the local environment are also clarified. In particular, it has been found that CO2 depletion occurs at high kinetics when the rotation is absent, giving rise to an increment of the competing hydrogen evolution reaction. This feature reflects in an enlargement of the diffusion resistance, which overcomes the charge transport one

Coupled Copper–Zinc Catalysts for Electrochemical Reduction of Carbon Dioxide

A catalyst plays a key role in the electrochemical reduction of CO2 to valuable chemicals and fuels. Hence, the development of efficient and inexpensive catalysts has attracted great interest from both the academic and industrial communities. In this work, low-cost catalysts coupling Cu and Zn are designed and prepared with a green microwave-assisted route. The Cu to Zn ratio in the catalysts can be easily tuned by adjusting the precursor solutions. The obtained Cu–Zn catalysts are mainly composed of polycrystalline Cu particles and monocrystalline ZnO nanoparticles. The electrodes with optimized Cu–Zn catalysts show enhanced CO production rates of approximately 200 μmol h−1 cm−2 with respect to those with a monometallic Cu or ZnO catalyst under the same applied potential. At the bimetallic electrodes, ZnO-derived active sites are selective for CO formation and highly conductive Cu favors electron transport in the catalyst layer as well as charge transfer at the electrode/electrolyte interface

Coupled Copper–Zinc Catalysts for Electrochemical Reduction of Carbon Dioxide

A catalyst plays a key role in the electrochemical reduction of CO2 to valuable chemicals and fuels. Hence, the development of efficient and inexpensive catalysts has attracted great interest from both the academic and industrial communities. In this work, low-cost catalysts coupling Cu and Zn are designed and prepared with a green microwave-assisted route. The Cu to Zn ratio in the catalysts can be easily tuned by adjusting the precursor solutions. The obtained Cu–Zn catalysts are mainly composed of polycrystalline Cu particles and monocrystalline ZnO nanoparticles. The electrodes with optimized Cu–Zn catalysts show enhanced CO production rates of approximately 200 μmol h−1 cm−2 with respect to those with a monometallic Cu or ZnO catalyst under the same applied potential. At the bimetallic electrodes, ZnO-derived active sites are selective for CO formation and highly conductive Cu favors electron transport in the catalyst layer as well as charge transfer at the electrode/electrolyte interface

Novel Insights into Sb-Cu Catalysts for Electrochemical Reduction of CO2

Catalysts play a vital role in electrochemical reduction of CO2 to valuable products. Only based on effective catalysts, CO2 electrolysis process can be advanced toward industrial application. In this work, we present a Sb-Cu2O material synthesized via one-pot microwave-assisted solvothermal route. The Sb-Cu2O derived bimetallic catalyst achieves a highest CO selectivity of 96% and good CO partial current densities of 37.3 and 74.0 mA cm−2 at − 0.8 and − 1.2 V vs. reversible hydrogen electrode (RHE), respectively. The Sb-Cu catalyst also displays good stability at current densities ranging from 5.6 to 100 mA cm−2. Additionally, for the first time, a complete theoretical study reveals the critical roles of Sb in selective CO2 conversion to CO on this bimetallic material, including stabilizing stepped Cu surfaces selective for the reaction, lowering energy barriers for the formation of key intermediate and favouring CO desorption

Syngas production by electrocatalytic reduction of CO ₂ using Ag-decorated TiO ₂ nanotubes

Huge efforts have been done in the last years on electrochemical and photoelectrochemical reduction of CO 2 to offer a sustainable route to recycle CO 2 . A promising route is to electrochemically reduce CO 2 into CO which, by combination with hydrogen, can be used as a feedstock to different added-value products or fuels. Herein, perpendicular oriented TiO 2 nanotubes (NTs) on the electrode plate were grown by anodic oxidation of titanium substrate and then decorated by a low loading of silver nanoparticles deposited by sputtering (i.e. Ag/TiO 2 NTs). Due to their quasi one-dimensional arrangement, TiO 2 NTs are able to provide higher surface area for Ag adhesion and superior electron transport properties than other Ti substrates (e.g. Ti foil and TiO 2 nanoparticles), as confirmed by electrochemical (CV, EIS, electrochemical active surface area) and chemical/morphological analysis (FESEM, TEM, EDS). These characteristics together with the role of the TiO 2 NTs to enhance the stability of CO 2 ·- intermediate formed due to titania redox couple (Ti IV /Ti III ) lead to an improvement of the CO production in the Ag/TiO 2 NTs electrodes. Particular attention has been devoted to reduce the loading of noble metal in the electrode(14.5 %w/%w) and to increase the catalysts active surface area in order to decrease the required overpotential. </p

Zn- and Ti-doped SnO2 for enhanced electroreduction of carbon dioxide

The electrocatalytic reduction of CO2 into useful fuels, exploiting rationally designed, inexpensive, active, and selective catalysts, produced through easy, quick, and scalable routes, represents a promising approach to face today’s climate challenges and energy crisis. This work presents a facile strategy for the preparation of doped SnO2 as an efficient electrocatalyst for the CO2 reduction reaction to formic acid and carbon monoxide. Zn or Ti doping was introduced into a mesoporous SnO2 matrix via wet impregnation and atomic layer deposition. It was found that doping of SnO2 generates an increased amount of oxygen vacancies, which are believed to contribute to the CO2 conversion efficiency, and among others, Zn wet impregnation resulted the most efficient process, as confirmed by X-ray photoelectron spectroscopy analysis. Electrochemical characterization and active surface area evaluation show an increase of availability of surface active sites. In particular, the introduction of Zn elemental doping results in enhanced performance for formic acid formation, in comparison to un-doped SnO2 and other doped SnO2 catalysts. At -0.99 V versus reversible hydrogen electrode, the total faradaic efficiency for CO2 conversion reaches 80%, while the partial current density is 10.3 mA cm-2. These represent a 10% and a threefold increases for faradaic efficiency and current density, respectively, with respect to the reference un-doped sample. The enhancement of these characteristics relates to the improved charge transfer and conductivity with respect to bare SnO2