Highly Selective Tandem Electroreduction of CO2 to Ethylene over Atomically Isolated Nickel–Nitrogen Site/Copper Nanoparticle Catalysts
TL;DR: In this paper, an earth-abundant elements-based tandem electrocatalyst PTF(Ni)/Cu is constructed by uniformly dispersing Cu nanoparticles (NPs) on the porphyrinic triazine framework anchored with atomically isolated nickel-nitrogen sites for the enhanced CO2 RR to produce C2 H4.
Abstract: Herein, an effective tandem catalysis strategy is developed to improve the selectivity of the CO2 RR towards C2 H4 by multiple distinct catalytic sites in local vicinity. An earth-abundant elements-based tandem electrocatalyst PTF(Ni)/Cu is constructed by uniformly dispersing Cu nanoparticles (NPs) on the porphyrinic triazine framework anchored with atomically isolated nickel-nitrogen sites (PTF(Ni)) for the enhanced CO2 RR to produce C2 H4 . The Faradaic efficiency of C2 H4 reaches 57.3 % at -1.1 V versus the reversible hydrogen electrode (RHE), which is about 6 times higher than the non-tandem catalyst PTF/Cu, which produces CH4 as the major carbon product. The operando infrared spectroscopy and theoretic density functional theory (DFT) calculations reveal that the local high concentration of CO generated by PTF(Ni) sites can facilitate the C-C coupling to form C2 H4 on the nearby Cu NP sites. The work offers an effective avenue to design electrocatalysts for the highly selective CO2 RR to produce multicarbon products via a tandem route.
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TL;DR: In this article , N-doped carbon aerogels supporting Ni single-atom sites (Ni-NCA-X, X = 10, 20) were fabricated by pyrolyzing Ni/Zn bimetallic zeolitic imidazolate framework (Ni/ZN-ZIF-8)/carboxymethylcellulose composite gels.
62 citations
TL;DR: In this article , the authors highlight unique single-atom catalysts for conversion of CO2 into high-efficiency carbon energy, for example, through photocatalytic, electrocatalytic and thermal catalytic hydrogenation technologies, to convert CO 2 into hydrocarbon fuels (CO, CH4, HCOOH, CH3OH and multicarbon [C2+] products).
Abstract: Currently, more than 86% of global energy consumption is still mainly dependent on traditional fossil fuels, which causes resource scarcity and even emission of high amounts of carbon dioxide (CO2), resulting in a severe “Greenhouse effect.” Considering this situation, the concept of “carbon neutrality” has been put forward by 125 countries one after another. To achieve the goals of “carbon neutrality,” two main strategies to reduce CO2 emissions and develop sustainable clean energy can be adopted. Notably, these are crucial for the synthesis of advanced single-atom catalysts (SACs) for energy-related applications. In this review, we highlight unique SACs for conversion of CO2 into high-efficiency carbon energy, for example, through photocatalytic, electrocatalytic, and thermal catalytic hydrogenation technologies, to convert CO2 into hydrocarbon fuels (CO, CH4, HCOOH, CH3OH, and multicarbon [C2+] products). In addition, we introduce advanced energy conversion technologies and devices to replace traditional polluting fossil fuels, such as photocatalytic and electrocatalytic water splitting to produce hydrogen energy and a high-efficiency oxygen reduction reaction (ORR) for fuel cells. Impressively, several representative examples of SACs (including d-, ds-, p-, and f-blocks) for CO2 conversion, water splitting to H2, and ORR are discussed to describe synthesis methods, characterization, and corresponding catalytic activity. Finally, this review concludes with a description of the challenges and outlooks for future applications of SACs in contributing toward carbon neutrality.
51 citations
07 Oct 2021
TL;DR: In this article, a review comprehensively summarizes the progress in thermo−catalysis of CO2 conversion by reticular framework−based catalysts to afford chemicals such as cyclic carbonates, cyclic carbamates, formamides, carboxylic acid, carbon monoxide, formate, methanol, methane, and light olefins.
Abstract: Reticular frameworks including metal−organic frameworks (MOFs) and covalent organic frameworks (COFs), and their derived materials have drawn global attention in the capture and conversion of CO2 as a cheap feedstock into fine chemicals and fuels due to their facile synthesis and programmable highly porous structures. This review comprehensively summarizes the progress in thermo−catalysis of CO2 conversion by reticular framework−based catalysts to afford chemicals such as cyclic carbonates, cyclic carbamates, formamides, carboxylic acid, carbon monoxide, formate, methanol, methane, and light olefins. Firstly, the characteristics and advantages of MOF−based materials for CO2 conversion are introduced. Secondly, the characteristics and advantages of COF−based materials for CO2 conversion are presented. Subsequently, the CO2 conversion reactions are briefly classified and discussed. Particularly, MOF or COF−based catalysts for each reaction are summarized in terms of catalyst design, catalytic performance and catalytic mechanism. Finally, the perspectives for further development of reticular framework−based catalysts for efficient CO2 conversion are discussed. We hope this review can provide an inspiration for the rational design of porous crystalline materials for thermal catalytic CO2 conversion.
41 citations
TL;DR: In this article, 3D imide-bonded COFs were constructed via the imidization reaction between phthalocyanine-based tetraanhydride and 1,3,5,7-tetra(4-aminophenyl)adamantine.
Abstract: Synthesis of functional 3D COFs with irreversible bond is challenging. Herein, 3D imide-bonded COFs were constructed via the imidization reaction between phthalocyanine-based tetraanhydride and 1,3,5,7-tetra(4-aminophenyl)adamantine. These two 3D COFs are made up of interpenetrated pts networks according to powder X-ray diffraction and gas adsorption analyses. CoPc-PI-COF-3 doped with carbon black has been employed to fabricate the electrocatalytic cathode towards CO2 reduction reaction within KHCO3 aqueous solution, displaying the Faradaic efficiency of 88-96 % for the CO2 -to-CO conversion at the voltage range of ca. -0.60 to -1.00 V (vs. RHE). In particular, the 3D porous structure of CoPc-PI-COF-3 enables the active electrocatalytic centers occupying 32.7 % of total cobalt-phthalocyanine subunits, thus giving a large current density (jCO ) of -31.7 mA cm-2 at -0.90 V. These two parameters are significantly improved than the excellent 2D COF analogue (CoPc-PI-COF-1, 5.1 % and -21.2 mA cm-2 ).
38 citations
TL;DR: In this article , the spatial separation of triazine and acetylene cores leads to efficient charge separation and suppressed charge recombination, and C═C linkage facilitates electrons transport over the skeletons.
Abstract: Covalent organic frameworks (COFs) are an ideal template for photocatalytic H2O2 synthesis because of the tunable chemical structures and semiconductor properties. However, the photoactivity for COFs is still under-improved due to the inefficient intrinsic charge generation, fast recombination of photogenerated charges, and limited electron transport along the frameworks. Herein, spatially separated and synergistic triazine and acetylene units are first integrated into COFs (EBA-COF and BTEA-COF) for photocatalytic H2O2 production. The spatial separation of triazine and acetylene cores leads to efficient charge separation and suppressed charge recombination, and C═C linkage facilitates electrons transport over the skeletons. Both experimental and computational results suggested that triazine and acetylene units synergistically promote H2O2 synthesis in a two-electron pathway. The EBA-COF showed an attractive activity with a H2O2 production rate of 1830 μmol h–1 gcat–1, superior to that of most other COF-based catalysts. This study provides a method for designing photocatalysts with synergistic photocatalytic active sites based on vinylene-linked COFs.
36 citations
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TL;DR: In this paper, the authors studied the effect of CO2 adsorption strength on the production of CO at the Cu electrode in aqueous inorganic electrolytes and compared the mechanism of the Fishcher-Tropsch reaction.
Abstract: Electroreduction of CO2 at Cu in aqueous inorganic electrolytes was studied by means of voltammetric, coulometric and chronopotentiometric measurements. CO, CH4, C2H4, EtOH and PrnOH are produced at ambient temperatures. Formation of CO predominates at less negative potentials (more positive than –1.2 V vs. NHE); hydrocarbons and alcohols are favourably produced below –1.3 V vs. NHE, where the Faradaic efficiency of CO drops. CO, formed as an intermediate from CO2, is adsorbed on the Cu electrode, interfering with cathodic hydrogen formation. The adsorption strength of CO on Cu is very weak as compared with that on Pt. Adsorbed CO is reduced to Hydrocarbons and alcohols at more negative potentials. The product distribution from CO2 depends strongly upon the electrolytes employed. Formation of C2H4 and alcohols is favoured in KCl, K2SO4, KClO4 and dilute HCO–3 solutions, whereas CH4 is preferentially produced in relatively concentrated HCO–3 and phosphate solutions. The product selectivity depends upon availability of hydrogen or protons on the surface, which is controlled by pH at the electrode. The pH at the electrode is greatly affected by the electrolyte, since OH– is released in the electrode reactions. The production of hydrocarbons and alcohols is discussed in comparison with the mechanism of the Fishcher–Tropsch reaction.
1,135 citations
TL;DR: Several promising strategies, including surface engineering, chemical modification, nanostructured catalysts, and composite materials, are proposed to facilitate the future development of CO2 electroreduction.
Abstract: In view of the climate changes caused by the continuously rising levels of atmospheric CO2 , advanced technologies associated with CO2 conversion are highly desirable. In recent decades, electrochemical reduction of CO2 has been extensively studied since it can reduce CO2 to value-added chemicals and fuels. Considering the sluggish reaction kinetics of the CO2 molecule, efficient and robust electrocatalysts are required to promote this conversion reaction. Here, recent progress and opportunities in inorganic heterogeneous electrocatalysts for CO2 reduction are discussed, from the viewpoint of both experimental and computational aspects. Based on elemental composition, the inorganic catalysts presented here are classified into four groups: metals, transition-metal oxides, transition-metal chalcogenides, and carbon-based materials. However, despite encouraging accomplishments made in this area, substantial advances in CO2 electrolysis are still needed to meet the criteria for practical applications. Therefore, in the last part, several promising strategies, including surface engineering, chemical modification, nanostructured catalysts, and composite materials, are proposed to facilitate the future development of CO2 electroreduction.
1,130 citations
TL;DR: This work adopts metal-organic frameworks (MOFs) to assist the preparation of a catalyst containing single Ni sites for efficient electroreduction of CO2 and presents some guidelines for the rational design and accurate modulation of nanostructured catalysts at the atomic scale.
Abstract: Single-atom catalysts often exhibit unexpected catalytic activity for many important chemical reactions because of their unique electronic and geometric structures with respect to their bulk counterparts. Herein we adopt metal–organic frameworks (MOFs) to assist the preparation of a catalyst containing single Ni sites for efficient electroreduction of CO2. The synthesis is based on ionic exchange between Zn nodes and adsorbed Ni ions within the cavities of the MOF. This single-atom catalyst exhibited an excellent turnover frequency for electroreduction of CO2 (5273 h–1), with a Faradaic efficiency for CO production of over 71.9% and a current density of 10.48 mA cm–2 at an overpotential of 0.89 V. Our findings present some guidelines for the rational design and accurate modulation of nanostructured catalysts at the atomic scale.
1,005 citations
TL;DR: The results demonstrate that the roughness of oxide-derived copper catalysts plays only a partial role in determining the catalytic performance, while the presence of copper+ is key for lowering the onset potential and enhancing ethylene selectivity.
Abstract: There is an urgent need to develop technologies that use renewable energy to convert waste products such as carbon dioxide into hydrocarbon fuels. Carbon dioxide can be electrochemically reduced to hydrocarbons over copper catalysts, although higher efficiency is required. We have developed oxidized copper catalysts displaying lower overpotentials for carbon dioxide electroreduction and record selectivity towards ethylene (60%) through facile and tunable plasma treatments. Herein we provide insight into the improved performance of these catalysts by combining electrochemical measurements with microscopic and spectroscopic characterization techniques. Operando X-ray absorption spectroscopy and cross-sectional scanning transmission electron microscopy show that copper oxides are surprisingly resistant to reduction and copper(+) species remain on the surface during the reaction. Our results demonstrate that the roughness of oxide-derived copper catalysts plays only a partial role in determining the catalytic performance, while the presence of copper(+) is key for lowering the onset potential and enhancing ethylene selectivity.
854 citations
TL;DR: In this review, recent research advances in electrocatalytic CO2 reduction are summarized from both experimental and theoretical aspects and are expected to provide new insights into the further technique development and practical applications of CO2 electroreduction.
Abstract: The worldwide unrestrained emission of carbon dioxide (CO2) has caused serious environmental pollution and climate change issues. For the sustainable development of human civilization, it is very desirable to convert CO2 to renewable fuels through clean and economical chemical processes. Recently, electrocatalytic CO2 conversion is regarded as a prospective pathway for the recycling of carbon resource and the generation of sustainable fuels. In this review, recent research advances in electrocatalytic CO2 reduction are summarized from both experimental and theoretical aspects. The referred electrocatalysts are divided into different classes, including metal–organic complexes, metals, metal alloys, inorganic metal compounds and carbon-based metal-free nanomaterials. Moreover, the selective formation processes of different reductive products, such as formic acid/formate (HCOOH/HCOO−), monoxide carbon (CO), formaldehyde (HCHO), methane (CH4), ethylene (C2H4), methanol (CH3OH), ethanol (CH3CH2OH), etc. are introduced in detail, respectively. Owing to the limited energy efficiency, unmanageable selectivity, low stability, and indeterminate mechanisms of electrocatalytic CO2 reduction, there are still many tough challenges need to be addressed. In view of this, the current research trends to overcome these obstacles in CO2 electroreduction field are summarized. We expect that this review will provide new insights into the further technique development and practical applications of CO2 electroreduction.
613 citations