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![Metal-macrocyclic complexes as electrocatalysts for CO 2 reduction. a) Investigated iron porphyrins. Reproduced with permission. [39] Copyright 2016, American Association for the Advancement of Science. b) Schematic mechanism of the electrochemical CO 2 reduction using Co protoporphyrin. Reproduced with permission. [40] Copyright 2015, Macmillan Publishers Limited.](publication/320119432/figure/fig1/AS:614007417348111@1523402184663/Metal-macrocyclic-complexes-as-electrocatalysts-for-CO-2-reduction-a-Investigated-iron.png)
Metal-macrocyclic complexes as electrocatalysts for CO 2 reduction. a) Investigated iron porphyrins. Reproduced with permission. [39] Copyright 2016, American Association for the Advancement of Science. b) Schematic mechanism of the electrochemical CO 2 reduction using Co protoporphyrin. Reproduced with permission. [40] Copyright 2015, Macmillan Publishers Limited.
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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 pr...
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... Since then, numerous of researches related to metal-macro- cyclic complexes have been come forth. Acted as an applicable and desirable "Trash to Treasure" approach, [39] the greenhouse gas CO 2 can be effectively transferred into carbon monoxide (CO) using different kinds of Fe-porphyrin molecules, as illustrated in Figure 1a. Typically, iron 5,10,15,20-tetrakis(2′,6′- dihydroxylphenyl)-porphyrin (Fe TDHPP) could achieve a stable electrocatalytic performance over 4 h for CO generation with a Faradaic yield above 90%, attributing to the high local proton concentration of phenolic hydroxyl. ...
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... cobalt-protoporphyrin electrocatalyst loaded on pyrolytic graphite electrode can convert CO 2 mainly into CO in acidic conditions, [40] showing high elec- trocatalytic activity comparable to other porphyrin-based mole- cules in previous reports at a lower overpotential (0.5 V). The pH-dependent activity and selectivity are shown in Figure 1b. Besides, a composite electrode prepared by the electrodeposition of [Cu(cyclam)](ClO 4 ) 2 complex (cyclam = 1,4,8,11-tetraazacy- clotetradecane) can reduce CO 2 into HCOOH with a Faradaic efficiency of 90% in dimethyl formamide (DMF)/H 2 O mixture (97:3, v/v). ...
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... some reports have investigated the activity of Cu alloys. Compared to Au or Cu NPs, nanosized Au 3 Cu alloys assembled into ordered monolayers [121] showed higher Faradaic efficiency for CO production (Figure 10a). Both the electronic effect and geometric effect of Au m Cu n alloys should be taken into consideration for the selective CO production and the des- orption ability of *COOH. ...
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... higher d-band levels of Cu can enhance the binding capability of *COOH and *CO, which is conducive to the production of hydrocarbons. However, when referred to the geometric effect, Cu atoms next to the AuC bonds can further stabilize *COOH and lead to the genera- tion of CO (Figure 10b-d). Therefore, an appropriate content of Cu in Au-Cu alloys can promote CO production. ...
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... The *COOH intermediates could be tightly bound on the surface of Ni and the introduction of Ga can weaken the Ni-CO interac- tion, therefore Ni and Ga synergistically increased the yields of C 2 hydrocarbons and avoided the poisoning of CO on the cata- lyst surface. Analyzed by a computational calculation method (Figure 10e,f), W-Au alloy was regarded as a suitable candidate to decrease the overpotential for *COO − formation and sup- press unfavorable *H adsorption for methanol production, [125] possibly followed a pathway: CO 2 → *COO − → CO ads → CHO ads → CH 3 O ads → methanol. Sun et al. developed a Mo-Bi bimetallic electrocatalyst with high CH 3 OH selectivity, which achieved a maximum Faradaic efficiency of 71.2% in acetoni- trile with the assistance of ion liquids. ...
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... Xie and co-workers synthesized ultrathin Co 3 O 4 layers with 1.72 nm thickness as an effective electrocatalyst, showing an optimum 64.3% Faradaic efficiency for HCOO − production after 20 h reaction. [130] Later, the same group prepared partially oxi- dized Co 4-atomic-layers with an average thickness of 0.84 nm (Figure 11a-d), and achieved a ultrahigh HCOO − selectivity of 90.1% over 40 h. [131] The Co based atomic layers possessed abundant active sites, and the increased charge density near Fermi level could improve electronic conductivity. ...
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... Tafel slopes (≈59 mV dec −1 , Figure 11e) and preferable CO 2 adsorption capability (Figure 11f) of partially oxidized Co 4-atomic-layers indicated the good properties for CO 2 activation and *COO − intermediate stabilization. ...
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... Tafel slopes (≈59 mV dec −1 , Figure 11e) and preferable CO 2 adsorption capability (Figure 11f) of partially oxidized Co 4-atomic-layers indicated the good properties for CO 2 activation and *COO − intermediate stabilization. ...
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... Nørskov and co-workers investigated the active edge sites of MoS 2 , MoSe 2 , and Ni-doped MoS 2 (Ni-MoS 2 ) simulated by DFT method. [135] The *COOH and *CHO intermediates prefer to attach to bridging S or Se atoms, while *CO intermediates trend to bind with the edge sites of metal atoms (Figure 12a). All edges were involved in CO evolution, while the S edges of Ni-MoS 2 and the Mo edges of MoSe 2 could further turn CO to hydrocarbons or alcohols. ...
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... edges were involved in CO evolution, while the S edges of Ni-MoS 2 and the Mo edges of MoSe 2 could further turn CO to hydrocarbons or alcohols. Inspired by this, a cost-effective MoS x electrocatalyst was introduced, which can produce syngas (CO and H 2 ) at a low overpotential of ≈290 mV and achieve a maximum Faradaic efficiency of 85.1% for CO yield with the assistance of reduced graphene oxide (rGO) and polyethylen- imine (PEI) (Figure 12b,c). [136] In 2016, Nørskov and co-workers found that the combination of dopant metal sites (*CO binding sites) and S binding sites (*COOH, *CHO, and *COH binding sites) on metal-doped MoS 2 can provide two different linear- scaling relationships, which synergistically result in enhanced CO 2 reduction performance than pristine Mo metal. ...
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... at an onset potential of −0.55 V (vs RHE), of which free ener- getics of CO hydrogenation was less than that of conventional Cu metal. [141] The DFT-calculated free energies for CO 2 reduc- tion to CH 4 on Cu(211) surface are displayed in Figure 12d, which shows that the major energy-consuming step for CH 4 generation is the protonation of adsorbed *CO (−0.74 V vs RHE). In contrast, CO 2 molecules were preferably adsorbed on Mo 2 C (100) surface ( Figure 12), followed by the dissociation of CO bonds at the initial reaction stage before protonation. ...
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... The DFT-calculated free energies for CO 2 reduc- tion to CH 4 on Cu(211) surface are displayed in Figure 12d, which shows that the major energy-consuming step for CH 4 generation is the protonation of adsorbed *CO (−0.74 V vs RHE). In contrast, CO 2 molecules were preferably adsorbed on Mo 2 C (100) surface ( Figure 12), followed by the dissociation of CO bonds at the initial reaction stage before protonation. Once the *O intermediates were generated by the CO bond fission, the protonation was easily accessible because of a lower potential demand (about −0.20 V vs RHE). ...
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... CNTs (NCNTs) could realize effective CO 2 capture and high product selectivity for CO generation at a sig- nificantly decreased overpotential than pristine CNTs. [142,143] Compared to pristine CNTs, the introduction of pyridinic-N into bamboo-shaped NCNTs (Figure 13a) led to higher electrical conductivity and achieved a Faradaic efficiency of 80% for CO generation. [144] Among the different N defects (Figure 13b), pyridinic-N sites exhibited the highest binding capability with CO 2 molecules and the lowest absolute overpotential (0.20 V) for *COOH formation, which promoted the CO formation. ...
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... Compared to pristine CNTs, the introduction of pyridinic-N into bamboo-shaped NCNTs (Figure 13a) led to higher electrical conductivity and achieved a Faradaic efficiency of 80% for CO generation. [144] Among the different N defects (Figure 13b), pyridinic-N sites exhibited the highest binding capability with CO 2 molecules and the lowest absolute overpotential (0.20 V) for *COOH formation, which promoted the CO formation. Other than pyridinic-N, the existence of quaternary-N or pyr- rolic-N could stabilize the radical active intermediates and lower the reduction barriers. ...
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... The pyridinic-N or pyrrolic-N species resulted in stronger CO 2 adsorption and lower energy barrier for the formation of *COOH intermediates. Similarly, the incorporation of pyridinic-N defects into 3D graphene foam can also lower the free energy barrier to form adsorbed *COOH and facilitate the CO yield (Figure 13c,d). [150] The cor- responding free energy diagrams for selective CO generation on different sites of N-doped graphene and pristine graphene through the lowest energy-consuming pathway are explic- itly shown in Figure 13e. ...
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... the incorporation of pyridinic-N defects into 3D graphene foam can also lower the free energy barrier to form adsorbed *COOH and facilitate the CO yield (Figure 13c,d). [150] The cor- responding free energy diagrams for selective CO generation on different sites of N-doped graphene and pristine graphene through the lowest energy-consuming pathway are explic- itly shown in Figure 13e. The excess overpotential is resulted from the uphill barrier of the first electron-transfer rate-deter- mine step for *COOH formation. ...
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... excess overpotential is resulted from the uphill barrier of the first electron-transfer rate-deter- mine step for *COOH formation. The *COOH intermediates have good affinity with N defects, and the free energy barrier for *COOH adsorption decreases significantly on pyridinic-or pyrrolic-N sites rather than graphitic-N sites (Figure 13f). Sub- sequently, the second proton-coupled electron transfer becomes thermodynamically easier for the formation of adsorbed *CO (or CO). ...
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The electrocatalytic reduction of CO2 on Au-Pt bimetallic catalysts with different compositions was evaluated, offering a platform for uncovering the correlation between the catalytic activity and the surface composition of bimetallic electrocatalysts. The Au-Pt alloy films were synthesized by a magnetron sputtering co-deposition technique with tun...
Citations
... [21][22][23] In addition, hydrogen evolution, a reaction competing with CO 2 /CO reduction, is necessary to study, especially in aqueous systems. 24,25 A study reported that these two descriptors can explain CO 2 reduction to products other than CO (hydrocarbons or alcohols). 26 Therefore, herein, the adsorption strengths of CO and H species to the surface, namely, ΔE CO and ΔE H , respectively, are used to evaluate the CO 2 RR performance. ...
Carbon dioxide reduction is a major step toward building a cleaner and safer environment. There is a surge of interest in exploring high-entropy alloys (HEAs) as active catalysts for CO2 reduction; however, so far, it is mainly limited to quinary HEAs. Inspired by the successful synthesis of octonary and denary HEAs, herein, the CO2 reduction reaction (CO2RR) performance of an HEA composed of Ag, Au, Cu, Pd, Pt, Co, Ga, Ni, and Zn is studied by developing a high-fidelity graph neural network (GNN) framework. Within this framework, the adsorption site geometry and physics are employed through the featurization of elements. Particularly, featurization is performed using various intrinsic properties, such as electronegativity and atomic radius, to enable not only the supervised learning of CO2RR performance descriptors, namely, CO and H adsorption energies, but also the learning of adsorption physics and generalization to unseen metals and alloys. The developed model evaluates the adsorption strength of ∼3.5 and ∼0.4 billion possible sites for CO and H, respectively. Despite the enormous space of the AgAuCuPdPtCoGaNiZn alloy and the rather small size of the training data, the GNN framework demonstrated high accuracy and good robustness. This study paves the way for the rapid screening and intelligent synthesis of CO2RR-active and selective HEAs.
... [1] The rising awareness of the importance of effectively converting CO 2 into valuable chemical products or carbonaceous fuels. [2] The electrochemical CO 2 reduction reaction (eCO 2 RR) has gained considerable attention in recent years due to its potential to utilize intermittent renewable energy sources (such as tidal, solar, and wind energy, etc.). [3] From an industrial perspective, to minimize separation costs, the preference lies in producing a single high-selectivity product as opposed to generating multiple low-selectivity products. ...
... Furthermore, the electrolyte composition is also a critical factor influencing the eCO 2 RR. To investigate the electrocatalytic activity for the eCO 2 Figure S18, the catalytic performance for the eCO 2 RR on the Cd/Zn electrode in [Bmim]PF 6 -based electrolyte was better than those in [Bmim]ClO 4 -, [Bmim]OTf-, and [Emim]PF 6 -based electrolytes, indicating the strong association between [Bmim]PF 6 and CO 2 could improve the reaction rate of the eCO 2 RR to produce CO. For comparison, the eCO 2 RR of the Cd/Zn electrode was also performed in 0.5 M KHCO 3 aqueous solution at different applied potentials. ...
Transforming carbon dioxide (CO2) into valuable chemical products or carbonaceous fuels is a crucial strategy for addressing the impact of global climate change and energy challenges. Electrochemical CO2 reduction reaction (eCO2RR) shows promise in this regard, but challenges remain in the eCO2RR, such as poor electrocatalytic activity and low selectivity of the target product. In this study, we report a one‐step method of replacement reaction for synthesizing a cadmium layer on the zinc foil surface (named as the Cd/Zn electrode) for efficient eCO2RR to CO. The thicknesses of Cd layers could be easily adjusted by varying the molar concentration of Cd²⁺. The Cd/Zn electrode with an approximately 2.0 μm thick Cd layer exhibited superior electrocatalytic performance of the eCO2RR to CO in the ionic liquid‐containing electrolytes. The highest Faradaic efficiency of CO reached up to 99.0 % at −1.9 V vs. Ag/Ag⁺, and the maximum CO partial current density achieved 34.8 mA cm⁻² at −2.3 V vs. Ag/Ag⁺. The 3D fluffy Cd layer with a suitable thickness on the Zn foil surface provided abundant active sites, fast charge transfer rate, and strong adsorption ability of CO2⋅⁻ intermediates, which contributed to the enhancement of the electrocatalytic performance of the eCO2RR to CO.
... Note that Pt has been believed to be inactive toward CO 2 reduction, but recent studies revealed that it provides CH 4 under specific conditions [101] as will be described in detail later. The metal dependence of CO 2 reduction reactions can be explained in terms of the Sabatier principle [13,21,97,102] stating that the binding energy between the catalyst and the reactant (or an intermediate) should be neither too strong nor too weak for facile reaction [103]. The reaction pathways are determined by the adsorption energy of the reactant with the catalyst's surface as follows. ...
CO2 reduction and fixation are one of the most interesting topics in the fields of environmental electrochemistry and electrocatalysis. Many studies on CO2 electroreduction using various metal electrodes have been reported. However, this reaction requires a high overpotential in general, which lowers the energy conversion efficiency and prevents its practical applications to reduce CO2 emission to the atmosphere. The use of a membrane electrode assembly (MEA) is expected to be a breakthrough for the CO2 electroreduction. Particularly, methanation (converting CO2 into CH4) with MEAs incorporating Cu-based catalysts attracts special attention as a tool for carbon cycling, thanks to high faradaic efficiencies and relatively high energy conversion efficiencies. Different from Cu, Pt has long been recognized as an inactive catalyst for CO2 reduction. Contrary to the common consensus, MEAs incorporating a Pt-based electrocatalyst were found very recently to be as active as Cu-based catalysts toward methanation under specific reaction conditions. The high activity of Pt arises from a reaction mechanism different from that for Cu; most likely the Langmuir–Hinshelwood mechanism for Pt and the Eley–Rideal mechanism for Cu. This mini-review discusses CO2 electrochemical methanation using MEAs as a potential method for carbon capture. The CO2 reduction to CH4 using a H2-CO2 fuel cell is also presented.
Graphical Abstract
... There are various heating rates used in this process, with pyrolysis being the most commonly used method for extracting bio-oil from biomass. This bio-oil can subsequently be further processed into valuable chemicals or used as automotive fuel (Zhang et al., 2018). While direct combustion is straightforward and commonly used, it suffers from relatively poor thermal efficiency. ...
This proposed research investigates sustainable and innovative
use of biomass gasification for generating electricity. Biomass
gasification is a versatile and eco-friendly technology that converts
organic materials, such as agricultural residues, forestry waste, and
even municipal solid waste, into a valuable source of clean energy.
This research delves into the various aspects of this technology,
including its processes, efficiency, environmental impact, and
potential applications in power generation. Biomass gasification gas,
often referred to as syngas, presents a promising avenue for
addressing the rising energy demand while lowering greenhouse gas
emissions and preventing climate change.
... To achieve high efficiency in CO 2 reduction, however, it is necessary to have a sufficient number of active sites. It can electrochemically convert CO 2 into different products, such as hydrocarbons and alcohols, due to its electrochemical properties [11,[30][31][32]. Selectivity of the products is directly related to the active copper species and the morphology, however, an irregular surface structure can be present on the catalyst surface, where wires, particles, and aggregates can be distributed in a nearly random manner. ...
As a result of electrochemical conversion of carbon dioxide (CO2), value-added chemicals like as synthetic fuels and chemical feedstocks can be produced. In the current state of the art, copper-based materials are most widely used being the most effective catalysts for this reaction. It is still necessary to improve the reaction rate and product selectivity of CuOx for electrochemical CO2 reduction reaction (CO2RR). The main objective of this work was synthesized and evaluate the copper oxide electrocatalyst combined with silver (CuO 70% Ag 30%) for the conversion of carbon dioxide into synthetic fuels. The catalysts have been prepared by the oxalate method and assessed in a flow cell system. The results of electrochemical experiments were carried out at room temperature and at different potentials (-1.05 V–0.75 V vs. RHE in presence of 0.1 M KHCO3) and gas and liquid chromatographic analysis are summarized. The CuOx-based electrodes demonstrated the selective of ~ 25% at -0.55 V for formic acid (HCOOH) and over CuO -Ag and selective of ethylene at ~ 20% over CuOx at -1.05 V. Other products were formed as ethylene, ethanol, and propanol (C2H4, EtOH, PrOH) at more positive potentials. On the other hand, carbon monoxide, acetate, ethylene glycol, propinaldehyde, glycoaldehyde and glyoxal (CO, CH3COO, C2H6O2, C3H6O, C2H4O2, C2H2O2) have been formed and detected. Based on the results of these studies, it appears that the formation of synthetic fuels from CO2 at room temperature in alkaline environment can be very promising.
... The challenge during the efficient synthesis of CO 2 RR catalysts is caused by the fact that CO 2 is a thermally stable molecule and requires stable support for its activation [22]. Consequently, an extremely negative potential of − 1.49 V vs. reversible hydrogen electrode (RHE) is needed to activate CO 2 and form intermediates (*COOH/HCOO*) during CO 2 RR [23]. This thermodynamic barrier makes CO 2 RR particularly difficult. ...
The technology of electrocatalytic reduction of CO2 to produce hydrocarbon fuels not only alleviates energy shortages but also suppresses the greenhouse effect, demonstrating enormous potential applications. In this context, we aim to explore new reliable materials for reducing CO2 (CO2RR) through electrocatalysis. Hence, we investigated the performance of Cu3(C12X)2, where X signifies organic-ligands (N₁₂H₆, N₉H₃O₃, N₉H₃S₃, N₆O₆, N₆S₆) for the CO2RR using density functional theory (DFT). The 2D Cu3(C12X)2 monolayers show metallic characteristics because of the presence of adequate π electron conjugation network as-well-as a constructive interaction between the metal atom, organic-ligands, and benzene-rings, with the exception of Cu3(C12N9H3O3)2, which displayed semiconducting characteristic. The catalytic activity of Cu3(C12X)2 can be tuned by adjusting the organic-ligands' ability to facilitate interaction between the CO2RR intermediates and the metal complex (Cu-X4). Among all MOFs, Cu3(C12N6S6)2 have excellent CO2RR activity towards CO and formic acid. All other Cu3(C12X)2 monolayers demonstrated dynamic CO2RR catalytic activity as well as superior selectivity over hydrogen evolution (HER) suggesting that these materials have the potential to be useful as CO2RR electrocatalysts. This study introduces the concept of building MOFs with favorable features to meet the specific needs of a number of research domains including catalysis, energy conversion and storage.
... Notably, electrocatalysis has been demonstrated to be efficient in converting CO 2 into highvalued chemicals and fuels. [124][125][126] Based on the electro-reforming of plastic waste, the integrated valorization of CO 2 and plastic waste seems to be a prospective strategy, which involves the cathodic CO 2 reaction and anodic oxidation reaction of plastic waste simultaneously. ...
With large quantities and natural resistance to degradation, plastic waste raises growing environmental concerns in the world. To achieve the upcycling of plastic waste into value‐added products, the electrocatalytic‐driven process is emerging as an attractive option due to the mild operation conditions, high reaction selectivity, and low carbon emission. Herein, this review provides a comprehensive overview of the upgrading of plastic waste via electrocatalysis. Specifically, key electrooxidation processes including the target products, intermediates and reaction pathways in the plastic electro‐reforming process are discussed. Subsequently, advanced electrochemical systems, including the integration of anodic plastic monomer oxidation and value‐added cathodic reduction and photo‐involved electrolysis processes, are summarized. The design strategies of electrocatalysts with enhanced activity are highlighted and catalytic mechanisms in the electrocatalytic oxidation of plastic waste are elucidated. To promote the electrochemistry‐driven sustainable upcycling of plastic waste, challenges and opportunities are further put forward.
... Carbonbased molecules, i.e. CO2 reduction, are a widely studied approach to this problem [2][3][4] , but they have the inherent problem of releasing CO2 in their combustion. Therefore, they would be truly CO2 neutral only if the CO2 used in their synthesis was captured from the air, and the current lack of mature CO2 capture technologies may limit the large-scale viability of CO2 reduction [5][6][7] . ...
Understanding the physical and chemical basis of device operation is important for their development. While hydrogen fuel cells are a widely studied topic, direct ammonia fuel cells (DAFCs) are a smaller field with fewer studies. Although the theoretical voltage of a DAFC is approximately equal to that of a hydrogen fuel cell, the slow kinetics of the ammonia oxidation reaction hamper cell performance. Therefore, development of anode catalysts is especially needed for practical viability of the DAFCs. To study DAFC operation, specifically interactions between reaction kinetics and different transport phenomena, we developed a one-dimensional model of a DAFC and performed a sensitivity analysis for several parameters related to the cell operating conditions (e.g., temperature, relative humidity) and properties (e.g., catalyst loading). As expected, temperature and relative humidity were very important for cell power. However, while faster reaction kinetics improved the cell performance, simply increasing the catalyst loading did not always produce a comparable enhancement. These and other observations about the relative importance of the operating parameters should help to prioritize and guide future development of and research on DAFCs. Further studies are needed to understand and optimize e.g. humidity management in different scenarios.
... In contrast, proton-assisted multiple electron transfer processes can occur at lower negative potentials (-0.2~-0.6 V vs. SHE) on appropriate catalyst surfaces, which helps to stabilize reaction intermediates and subsequently leads to the formation of various CO 2 derivatives [47] . ...
Electrochemical conversion of carbon dioxide (CO2) into high-value chemicals and fuels driven by electricity derived from renewable energy has been recognized as a promising strategy to achieve carbon neutrality and create sustainable energy. Particularly from the viewpoint of the product values and the economic viability, selective CO2 reduction to formic acid/formate has shown great promise. Palladium (Pd) has been demonstrated as the only metal that can produce formic acid/formate perfectly near the equilibrium potential; yet, it still suffers from CO poisoning, poor stability and competitive CO pathway at high overpotentials. Herein, recent progress of Pd-based electrocatalysts for selective CO2 electroreduction and their mechanistic understanding are reviewed. First, the fundamentals of electrochemical CO2 reduction and the reaction pathway of formic acid/formate on Pd are presented. Then, recent advances in the rational design and nanoscale engineering strategies of Pd-based electrocatalysts for further improving CO2 reduction activity and selectivity to formic acid/formate product, including size control, morphology and shape control, alloying, heteroatom doping, surface-strain engineering, and phase control, are discussed from the perspectives of both experimental and computational aspects. Finally, we discuss the pertinent challenges and describe the future prospects and opportunities in terms of the development of electrocatalysts, electrolyzers and characterization techniques in this research field.
... The HCOO À species can also be further reduced to generate HCHO and CH 4 . 50 In addition, CO can be produced from CO 2 ER after the reduction by two electrons. If the resultant CO cannot be activated by electrocatalysts, CO tends to be released for producing CH 3 OH through a hydrogeneration process. ...
... Moreover, these intermediates can be further converted into alcohols or other hydrocarbons such as C 2 H 4 and C 2 H 6 through a dimerization pathway. 50,52 For heterogeneous CO 2 ER, the reaction path is a little different. Heterogeneous CO 2 ER usually involves the adsorption of CO 2 on the electrocatalyst surface, activation of the adsorbed CO 2 by the catalyst, and protonation of the activated CO 2 . ...
... The further dimerization of the [CAT-COOH]* intermediates can give rise to the hydrocarbons such as C 2 H 4 (Cu porphyrin complex as electrocatalyst, faradic efficiency 44%, current density 8.4 mA/ cm 2 ) and C 2 H 6 (Cu nanowires as electrocatalyst, faradic efficiency 20.3%, current density 4-5 mA/cm 2 ). 50 Although the above-mentioned value-added products have been reported from heterogeneous CO 2 ER methods, achieving high selectivity for value-added products is still challenging. The typical homogeneous CO 2 ER electrocatalysts are summarized in Table 3. ...
