Nanostructured heterogeneous catalysts for electrochemical reduction of CO2

Electrochemical reduction of CO₂ provides a sustainable solution to address the intermittent renewable electricity storage while recycling CO₂ to produce fuels and chemicals. Highly efficient catalytic materials and reaction systems are required to drive this process economically. This Review highlights the new trends in advancing the electrochemical reduction of CO₂ by developing and designing nanostructured heterogeneous catalysts. The activity, selectivity and reaction mechanism are significantly affected by the nano effects in nanostructured heterogeneous catalysts. In the future, energy efficiency and current density in electrochemical reduction of CO₂ need to be further improved to meet the requirements for practical applications.     

Copper-based metal-organic frameworks for electrochemical reduction of CO2

The electrochemical CO₂ reduction reaction (CO₂ER) is an emerging process that involves utilizing CO₂ to produce valuable chemicals and fuels by consuming excess electricity from renewable sources. Recently, Cu and Cu-based nanoparticles, as earth-abundant and economical metal sources, have been attracting significant interest. The chemical and physical properties of Cu-based nanoparticles are modified by different strategies, and CO₂ can be converted into multicarbon products. Among various Cu-based nanoparticles, Cu-based metal-organic frameworks (MOFs) are gaining increasing interest in the field of catalysis because of their textural, topological, and electrocatalytic properties. In this minireview, we summarized and highlighted the main achievements in the research on Cu-based MOFs and their advantages in the CO₂ER as electrocatalysts, supports, or precursors.     

纳米晶枝CuAu合金催化剂对二氧化碳电催化还原性能的研究

利用可再生清洁能源将CO2转化为CO和其他小分子是合成含碳燃料的可观方法之一.间歇性可再生能源存储的重要策略之一是将二氧化碳进行电化学还原.选择具有高活性和稳定性的电催化剂对于电化学还原CO2至关重要.在这项研究中,我们使用简单的电沉积方法合成了具有纳米晶枝状结构的CuAu合金电极.各项表征显示原子比约为1∶1的CuA...     

Recent advances in carbon-based materials for electrochemical CO2 reduction reaction

The increase of atmospheric CO₂ concentration has caused many environmental issues. Electrochemical CO₂ reduction reaction（CO₂RR） has been considered as a promising strategy to mitigate these challenges. The electrocatalysts with a low overpotential, high Faradaic efficiency, and excellent selectivity are of great significance for the CO₂RR. Carbon-based materials including metal-free carbon catalysts and metal-based carbon catalysts have shown great p...     

Ultrathin two-dimensional metal-organic framework nanosheets for efficient electrochemical CO2 reduction

Electrochemical CO2 reduction into CO or high-value products is regarded as a feasible pathway for energy conversion, which has attracted universal attention in...     

Key factors for designing single-atom metal-nitrogen-carbon catalysts for electrochemical CO2 reduction

The electrochemical CO₂ reduction (CO₂RR) is a sustainable approach to mitigate the increased CO₂ emissions and simultaneously produce value-added chemicals and fuels. Metal-nitrogen-carbon (M-N-C) based single-atom catalysts (SACs) have emerged as promising electrocatalysts for CO₂RR with high activity, selectivity, and stability. To design efficient SACs for CO₂RR, the key influence factors need to be understood. Here, we summarize recent achievements on M-N-C SACs for CO₂RR and highlight the significance of the key constituting factors, metal sites, the coordination environment, and the substrates, for achieving high CO₂RR performance. The perspective views and guidelines are provided for the future direction of developing M-N-C SACs as CO₂RR catalysts.     

Copper-indium hydroxides derived electrocatalysts with tunable compositions for electrochemical CO2 reduction

Bimetallic Cu-In hybrid electrocatalysts are promising noble metal-free catalysts for selective electrochem-ical CO2 reduction reaction (ECO2RR).Most reports sh...     

Cloride-derived copper electrode for efficient electrochemical reduction of CO2 to ethylene

Transformation of CuCl into cubic structure of bi-phasic Cu₂O-Cu (CB-Cu) enhanced production of ethylene from electrochemical reduction of CO₂.     

Quasi-square-shaped cadmium hydroxide nanocatalysts for electrochemical CO2 reduction with high efficiency

Powered by a renewable electricity source, electrochemical CO₂ reduction reaction is a promising solution to facilitate the carbon balance. However, it is still a challenge to achieve a desired product with commercial current density and high efficiency. Herein we designed quasi-square-shaped cadmium hydroxide nanocatalysts for CO₂ electroreduction to CO. It was discovered that the catalyst is very active and selective for the reaction. The current density could be as high as 200 mA cm⁻² with a nearly 100% selectivity in a commonly used H-type cell using the ionic liquid-based electrolyte. In addition, the faradaic efficiency of CO could reach 90% at a very low overpotential of 100 mV. Density functional theory studies and control experiments reveal that the outstanding performance of the catalyst was attributed to its unique structure. It not only provides low Cd–O coordination, but also exposes high activity (002) facet, which requires lower energy for the formation of CO. Besides, the high concentration of CO can be achieved from the low concentration CO₂via an adsorption-electrolysis device.

Quasi-square cadmium hydroxide nanocrystals (Cdhy-QS) showed outstanding performance for electroreduction CO₂ to CO.     

多金属氧酸盐材料在二氧化碳电催化还原领域中的研究进展

随着工业发展和全球人口的持续增长,人类对化石燃料的消耗日益增加,从而导致大气中二氧化碳含量的显著增加以及与之相伴的一系列环境问题.电化学还原二氧化碳制备高附加值的燃料和化学品具有稳定的效率和较高的经济可行性等特点,目前已成为一种有前景的策略来缓解当前全球面临的能源短缺和气候变暖问题.然而,电催化二氧化碳还原过程存在反应...     

Innovative strategies toward challenges in PV-powered electrochemical CO2 reduction

The solar energy-driven electrochemical CO2 reduction to value-added fuels or chemicals is considered as an attractive path to store renewable energy in the for...     

In situ Raman spectroscopy studies for electrochemical CO2 reduction over Cu catalysts

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Why heterogeneous single-atom catalysts preferentially produce CO in the electrochemical CO2 reduction reaction

Formate and CO are competing products in the two-electron CO₂ reduction reaction (2e CO₂RR), and they are produced via *OCHO and *COOH intermediates, respectively. However, the factors governing CO/formate selectivity remain elusive, especially for metal–carbon–nitrogen (M–N–C) single-atom catalysts (SACs), most of which produce CO as their main product. Herein, we show computationally that the selectivity of M–N–C SACs is intrinsically associated with the CO₂ adsorption mode by using bismuth (Bi) nanosheets and the Bi–N–C SAC as model catalysts. According to our results, the Bi–N–C SAC exhibits a strong thermodynamic preference toward *OCHO, but under working potentials, CO₂ is preferentially chemisorbed first due to a charge accumulation effect, and subsequent protonation of chemisorbed CO₂ to *COOH is kinetically much more favorable than formation of *OCHO. Consequently, the Bi–N–C SAC preferentially produces CO rather than formate. In contrast, the physisorption preference of CO₂ on Bi nanosheets contributes to high formate selectivity. Remarkably, this CO₂ adsorption-based mechanism also applies to other typical M–N–C SACs. This work not only resolves a long-standing puzzle in M–N–C SACs, but also presents simple, solid criteria (i.e., CO₂ adsorption modes) for indicating CO/formate selectivity, which help strategic development of high-performance CO₂RR catalysts.

This report discloses a nontrivial role of the CO₂ adsorption mode in governing the CO/formate selectivity of single-atom catalysts towards two-electron CO₂ reduction.     

One-step synthesis of ultra-small amount of Pd-Alloyed Zinc Nanosheets for efficient electrochemical CO2 reduction to CO

The practicality of the electrochemical CO₂ reduction technique depends on the development of cost-effective, robust, and highly selective catalysts. To achieve this goal, we have engineered self-supported 3D electrodes composed of Pd-Zn nanosheets (NSs) for CO₂ electrochemical reduction to CO with minimal Pd content. This innovative electrode with an increased surface area was created using an electrodeposition method employing a dynamic hydrogen bubble template. By precisely adjusting the Pd content, we improved the thickness, porosity, and surface area of the electrodes, resulting in a CO₂-to-CO selectivity reaching as high as 88.5 %, with an average of at least 80 % sustained over 10 hours. This remarkable improved activity can be attributed to the synergistic effects of an appropriate Pd/Zn atomic ratio as well as to the large surface area of nanosheets structures with rich edge active sites. Furthermore, to get around the limitations of CO₂ mass transfer, reactions were done at high pressures conditions ranging from 3 to 9.5 bar; this strategic approach yielded an outstanding partial current density of −304.6 mA cm⁻² for CO. These noteworthy findings establish concepts for constructing effective and earth-abundant CO-producing electrocatalysts.     

The atomic-level regulation of single-atom site catalysts for the electrochemical CO2 reduction reaction

The electrochemical CO₂ reduction reaction (CO₂RR) is viewed as a promising way to remove the greenhouse gas CO₂ from the atmosphere and convert it into useful industrial products such as methane, methanol, formate, ethanol, and so forth. Single-atom site catalysts (SACs) featuring maximum theoretical atom utilization and a unique electronic structure and coordination environment have emerged as promising candidates for use in the CO₂RR. The electronic properties and atomic structures of the central metal sites in SACs will be changed significantly once the types or coordination environments of the central metal sites are altered, which appears to provide new routes for engineering SACs for CO₂ electrocatalysis. Therefore, it is of great importance to discuss the structural regulation of SACs at the atomic level and their influence on CO₂RR activity and selectivity. Despite substantial efforts being made to fabricate various SACs, the principles of regulating the intrinsic electrocatalytic performances of the single-atom sites still needs to be sufficiently emphasized. In this perspective article, we present the latest progress relating to the synthesis and catalytic performance of SACs for the electrochemical CO₂RR. We summarize the atomic-level regulation of SACs for the electrochemical CO₂RR from five aspects: the regulation of the central metal atoms, the coordination environments, the interface of single metal complex sites, multi-atom active sites, and other ingenious strategies to improve the performance of SACs. We highlight synthesis strategies and structural design approaches for SACs with unique geometric structures and discuss how the structure affects the catalytic properties.

Electrochemical CO₂ reduction reaction (CO₂RR) is a promising way to remove CO₂ and convert it into useful industrial products. Single-atom site catalysts provide opportunities to regulate the active sites of CO₂RR catalysts at the atomic level.     

Advances in the electrochemical catalytic reduction of CO2 with metal complexes

Electrocatalytic CO₂ reduction has emerged as a promising strategy to effectively produce fuels and chemicals sustainably. In this regard, the study of electrochemical catalytic reduction of CO₂ with metal complexes is a powerful tool for both the development of catalysts that operated under desired conditions (low overpotentials, high catalytic rates and selectivity, and extended durability) and the understanding of basic principles in catalysis. To illustrate the state-of-the-art, this revision presents a selection of the most recent and remarkable findings reported in terms of key strategies to improve reaction rates, selectivity and mechanism understanding for the leading families of homogeneous catalysts.     

Theory assisted design of N-doped tin oxides for enhanced electrochemical CO2 activation and reduction

Clearly understanding the structure-function relationship and rational design of efficient CO_2 electrocatalysts are still the challenges.This article describes the molecular origin of high selectivity of formic acid on N-doped SnO_2 nanoparticles,which obtained via thermal treatment of g-C_3N_4 and SnCl_2·2H_2O precursor.Combined with density functional theory(DFT)calculations,we discover that N-doping effectively introduces oxygen vacancies and increases the charge density of Sn sites,which plays a positive role in CO_2 activation.In addition,N-doping further regulates the adsorption energy of*OCHO,*COOH,*H and promotes HCOOH generation.Benefited from above modulation,the obtained N-doped SnO_2 catalysts with oxygen vacancies(Ov-N-SnO_2)exhibit faradaic efficiency of 93% for C_1 formation,88% for HCOOH production and well-suppression of H_2 evolution over a wide range of potentials.