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Photoelectrochemical devices require solid anodes and cathodes for the easy assembling of the whole cell and thus redox catalysts need to be deposited on the electrodes. Typical catalyst deposition involves drop casting, spin coating, doctor blading or related techniques to generate modified electrodes where the active catalyst in contact with the electrolyte is only a very small fraction of the deposited mass. We have developed a methodology where the redox catalyst is deposited at the electrode based on supramolecular interactions, namely CH‐π and π–π between the catalyst and the surface. This generates a very well‐defined catalysts‐surface structure and electroactivity, together with a very large catalytic response. This approach represents a new anchoring strategy that can be applied to catalytic redox reactions in heterogeneous phase and compared to traditional methods involves about 4–5 orders of magnitude less mass deposition to achieve comparable activity and with very well‐behaved electroactivity and stability. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs), featuring highly uniform active sites, tunable coordination environments, and synergistic effects with support, have emerged as one of the most efficient catalysts for various reactions, particularly for electrochemical CO2 reduction (ECR). However, the scalability of SACs is restricted due to the limited choice of available support and problems that emerge when preparing SACs by thermal deposition. Here, an in situ reconstruction method for preparing SACs is developed with a variety of atomic sites, including nickel, cadmium, cobalt, and magnesium. Driven by electricity, different oxygen‐containing metal precursors, such as MOF‐74 and metal oxides, are directly atomized onto nitrogen‐doped carbon (NC) supports, yielding SACs with variable metal active sites and coordination structures. The electrochemical force facilitates the in situ generation of bonds between the metal and the supports without the need for additional complex steps. A series of MNxOy (M denotes metal) SACs on NC have been synthesized and utilized for ECR. Among these, NiNxOy SACs using Ni‐MOF‐74 as a metal precursor exhibit excellent ECR performance. This universal and general SAC synthesis strategy at room temperature is simpler than most reported synthesis methods to date, providing practical guidance for the design of the next generation of high‐performance SACs. [ABSTRACT FROM AUTHOR]

A copper porphyrin‐derived metal–organic framework electrocatalyst, FICN‐8, was synthesized and its catalytic activity for CO2 reduction reaction (CO2RR) was investigated. FICN‐8 selectively catalyzed electrochemical reduction of CO2 to CO in anhydrous acetonitrile electrolyte. However, formic acid became the dominant CO2RR product with the addition of a proton source to the system. Mechanistic studies revealed the change of major reduction pathway upon proton source addition, while catalyst‐bound hydride (*H) species was proposed as the key intermediate for formic acid production. This work highlights the importance of electrolyte composition on CO2RR product selectivity. [ABSTRACT FROM AUTHOR]

Microbial electrochemical processes are primary platforms for generating electricity or value-added products by relying on the interaction between electroactive microorganisms and electrodes by utilizing electron carriers like hydrogen and enzyme through the oxidation–reduction reactions. Microbial electrosynthesis (MES), initially introduced as electricity-driven bioproduction from CO2, offered a novel pathway to produce biochemicals that eventually contribute to the CO2 sequestration. While most of the previous reviews concentrate on these microbial electrochemical platforms jointly referred to as MXC, such as Microbial fuel cell and microbial electrolysis cell, MES has grown tremendously in recent years, requiring a severe update on the scientific information on this topic. In this mini-review, the significant achievements in MES, specifically towards the production of a wide array of specialty chemicals, have been addressed by summarizing the recent scientific breakthroughs of the MES technology. Furthermore, improving MES's performance through modification of electrodes and membranes and outlook section with the technical challenges and probable solutions have been discussed. The review summarizes the technological drawbacks of the MES's towards a sustainable commercial platform for industrial commodities production and proposes ways to overcome the existing technical challenges in a nutshell towards turning MES in a full-fledged industrial-scale production platform. [ABSTRACT FROM AUTHOR]

This paper presents metal-free N–S co-doped catalysts that synthesize in the presence of different S sources such as thiourea and polythiophene (Ptyf). The composition, morphology, and structure of the obtained sample are measured by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) method, X-ray diffraction (XRD), UV–vis spectroscopy, Fourier transform ınfrared-attenuated total reflection spectroscopy (FTIR-ATR), and X-ray photoelectron spectroscopy (XPS). Although the characterization measurements showed that the fabricated catalysts had a similar elemental composition, the polythiophene-based catalysts retained their polymer properties such as active surface area, conductivity, and conjugated chains. This result enhances the adsorption of CO2 to the catalyst surface and promotes the reduction of CO2 effectively. The only product is HCOOH with a faradaic efficiency of 84% which was achieved on P-N/S2-rGO (P: pyrolysis) at -0.6 V (Ag/AgCl). [ABSTRACT FROM AUTHOR]

[Display omitted] • Rare-earth Tb doped Pd 49 Ag 30 Te 4 alloy facilitates selective exposure of (1 1 1) crystal plane. • The doping of Tb accelerates electron transfer, promotes CO 2 adsorption as well as activation, and suppress H 2 evolution. • The introduction of Tb regulates d-band center of Pd 49 Ag 30 Te 4 , weakens the Pd − C bonding ability, and promotes the production of CO. Employing electric energy to convert carbon dioxide (CO 2) into valuable small molecules is a potentially practical method in energy storage and greenhouse gas alleviation. A huge challenge for electrocatalytic CO 2 reduction is to reduce overpotential to improve energy efficiency. Herein, we demonstrate that doping alloy Pd 49 Ag 30 Te 4 (PAT) with rare-earth element Tb is beneficial for selective exposure of (1 1 1) crystal plane, which is a highly active crystal plane for producing carbon monoxide (CO). The as-prepared Tb 2.9 PAT exhibited high electrocatalytic performance with 95.7 % CO faradic efficiency at − 0.8 V (vs RHE), far exceeding that of PAT, and coupled with good durability. In situ spectral study and theoretical calculations disclose that the introduction of Tb regulates the d-band center of PAT alloy, weakens the Pd − C bonding ability, and promotes the desorption of *CO in the rate-determining step. This study provides a method for doping induced selective exposure of crystal face, which provides new idea for improving catalytic performance. [ABSTRACT FROM AUTHOR]

The conversion of CO2 into formate through electrochemical methods is emerging as an elegant approach for industrial‐scale CO2 utilization in the near future. Although Bismuth (Bi)‐based materials have shown promise thank to their excellent selectivity, their limited reactivity remains a challenge. Herein, this study demonstrates a significant enhancement in the CO2‐to‐formate efficiency of Bi by incorporating ruthenium (Ru) atomic species. Ru single atom doped Bi exhibited a nearly twofold higher partial current density compared with pure Bi and Ru clusters doped Bi, while over 95% Faradaic efficiency (FE) is maintained. Through comprehensive investigations using a combined approach of electrochemical techniques, operando spectroscopy, and theoretical calculations, this study elucidates that the presence of Ru single atom promotes H2O dissociation and H* migration to Bi sites for CO2‐to‐formate conversion by significantly reducing the energy barrier via a H* spillover path. Besides, it is constructed Ru–Bi bridge sites for efficient CO2 hydrogenation via a non‐spillover path, which served as the major mechanism for CO2‐to‐formate conversion in Ru single atom doped Bi. [ABSTRACT FROM AUTHOR]

Atomic Fe sites enabled electrochemical carbon dioxide (CO2) reduction (ECO2R) to carbon monoxide (CO) at low overpotentials. However, the narrow potential ranges for selective CO2 conversion on atomic Fe sites hindered the CO production at high current densities. Therefore, unveiling the CO2 electroreduction processes and clarifying the catalytic mechanisms on different atomic Fe sites are important for better design of atomic Fe catalysts toward efficient ECO2R. Herein, the ECO2R processes on single‐atom, dual‐atom, and cluster Fe sites are systematically investigated, and clarify that the balanced water dissociation and CO2 protonation on dual‐atom Fe sites promote the efficient CO production. The dual‐atom Fe catalyst achieves Faradaic efficiencies of CO (FECO) above 92% over a wide potential range of −0.4–−0.9 V versus reversible hydrogen electrode and maintains FECO of 91% after 153‐h electrolysis in H‐type cell. Benefitting from the favorable CO2 protonation for ECO2R on dual‐atom Fe sites, pH‐universal CO2 electroreduction is achieved in alkali‐/acid‐/bicarbonate‐fed membrane electrode assembly electrolyzer, with FECO exceeds 98% in strongly acidic/alkaline and neutral mediums. The work reveals a water dissociation‐promoted CO2 electroreduction on dual‐atom Fe sites and presents a feasible regulation of atomic Fe sites for highly active/selective ECO2R. [ABSTRACT FROM AUTHOR]

Electrolyte plays crucial roles in electrochemical CO2 reduction reaction (e‐CO2RR), yet how it affects the e‐CO2RR performance still being unclarified. In this work, it is reported that Sn‐Zn hybrid oxide enables excellent CO2‐to‐HCOO− conversion in KHCO3 with a HCOO− Faraday efficiency ≈89%, a yield rate ≈0.58 mmol cm−2 h−1 and a stability up to ≈60 h at −0.93 V, which are higher than those in NaHCO3 and K2SO4. Systematical characterizations unveil that the surface reconstruction on Sn‐Zn greatly depends on the electrolyte using: the Sn‐SnO2/ZnO, the ZnO encapsulated Sn‐SnO2/ZnO and the Sn‐SnO2/Zn‐ZnO are reconstructed on the surface by KHCO3, NaHCO3 and K2SO4, respectively. The improved CO2‐to‐HCOO− performance in KHCO3 is highly attributed to the reconstructed Sn‐SnO2/ZnO, which can enhance the charge transportation, promote the CO2 adsorption and optimize the adsorption configuration, accumulate the protons by enhancing water adsorption/cleavage and limit the hydrogen evolution. The findings may provide insightful understanding on the relationship between electrolyte and surface reconstruction in e‐CO2RR and guide the design of novel electrocatalyst for effective CO2 reduction. [ABSTRACT FROM AUTHOR]

Dual‐atom catalysts (DACs) are promising for applications in electrochemical CO2 reduction due to the enhanced flexibility of the catalytic sites and the synergistic effect between dual atoms. However, precisely controlling the atomic distance and identifying the dual‐atom configuration of DACs to optimize the catalytic performance remains a challenge. Here, the Ni and Fe atomic pairs were constructed on nitrogen‐doped carbon support in three different configurations: NiFe‐isolate, NiFe‐N bridge, and NiFe‐bonding. It was found that the NiFe‐N bridge catalyst with NiN4 and FeN4 sharing two N atoms exhibited superior CO2 reduction activity and promising stability when compared to the NiFe‐isolate and NiFe‐bonding catalysts. A series of characterizations and density functional theory calculations suggested that the N‐bridged NiFe sites with an appropriate distance between Ni and Fe atoms can exert a more pronounced synergy. It not only regulated the suitable adsorption strength for the *COOH intermediate but also promoted the desorption of *CO, thus accelerating the CO2 electroreduction to CO. This work provides an important implication for the enhancement of catalysis by the tailoring of the coordination structure of DACs, with the identification of distance effect between neighboring dual atoms. [ABSTRACT FROM AUTHOR]

The reduction of CO2 has become a key role in reducing greenhouse gas emissions in efforts to search for long‐term responses to climate change. We report a couple of CO2‐reducing molecular catalysts based on earth‐abundant copper complexes. These are [Cu(DPA)(PyNAP)] (1) and [Cu(DPA)(PyQl)] (2) (where, DPA=pyridine‐2,6‐dicarboxylate, PyNAP=2‐(pyridin‐2‐yl)‐1,8‐naphthyridine, and PyQl=2‐(pyridin‐2‐yl)quinoline). The copper metal‐catalysed 2‐electron reduction of CO2 to CO in the presence of 2‐protons is challenging. These catalysts exhibit the production of CO gas in DMF/water mixtures, achieving an impressive Faradaic efficiency of 84 % and 72 % for complex 1 and 2 at −1.7 V vs. SCE, respectively, for selective CO2 reduction. The production of H2 due to 2H++2e− was also observed as a byproduct through the competitive proton reduction reaction. This was cross‐verified by online gas and mass analysis. A comprehensive series of electrochemical experiments have substantiated the homogeneous behaviour exhibited by these molecular electrocatalysts. Our investigations confirmed the stability of the electrocatalysts under the electrocatalytic conditions. The mechanistic pathways were proposed to work with the EECC and ECEC (E: electrochemical and C: chemical) mechanisms. A CO2 insertion into an in‐situ generated hydride from the Cu‐center generates CO through the favourable path. This critical path kinetically favors excess Faradaic efficiency in 1 than 2, which agrees with the computational investigation. [ABSTRACT FROM AUTHOR]

Tin (Sn)‐based materials are expected to realize efficient CO2 electroreduction into formate. Herein, we constructed a heterojunction by depositing Cu on Cu‐doped SnS2 nanosheets. During the electrochemical reaction, this heterojunction evolves to a highly active phase of Cu2O@Cu6Sn5 while maintaining its two‐dimensional morphology. Specifically, a partial current density of 35 mA cm−2 with an impressive faradaic efficiency of 93 % for formate production was achieved over the evolved heterojunction. In situ and ex situ experiments elucidated the formation mechanism of the Cu₂O@Cu₆Sn₅ heterojunction. Cu₆Sn₅ nanosheets were formed via a stepwise desulfurization process, while Cu₂O was generated through its reaction with hydroxyl radicals. This evolved heterojunction with a high electrochemically active surface area synergistically stabilized the *OCHO intermediate, thereby significantly enhancing the selectivity and activity. Our findings provide insight into the structural evolution process and guide the development of selective electrocatalysts for CO2 reduction. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) to generate chemical fuels such as formate presents a promising route to a carbon‐neutral future. However, its practical application is hindered by the competing CO production and hydrogen evolution reaction (HER), as well as the lack of pH‐universal catalysts. Here, Te‐modified Bi nanorods (Te−Bi NRs) were synthesized through in situ reconstruction of Bi2Te4O11 NRs under the CO2RR condition. Our study illustrates that the complex reconstruction process of Bi2Te4O11 NRs during CO2RR could be decoupled into three distinct steps, i.e. the destruction of Bi2Te4O11, the formation of Te/Bi phases, and the dissolution of Te. The thus‐obtained Te−Bi NRs exhibit remarkably high performance in CO2RR towards formate production, showing high activity, selectivity, and stability across all pH conditions (acidic, neutral, and alkaline). In a flow cell reactor under neutral, alkaline, or acidic conditions, the catalysts achieved HCOOH Faradaic efficiencies of up to 94.3 %, 96.4 %, and 91.0 %, respectively, at a high current density of 300 mA cm−2. Density functional theory calculations, along with operando spectral measurements, reveal that Te manipulates the Bi sites to an electron‐deficient state, enhancing the adsorption strength of the *OCHO intermediate, and significantly suppressing the competing HER and CO production. This study highlights the substantial influence of catalyst reconstruction under operational conditions and offers insights into designing highly active and stable electrocatalysts towards CO2RR. [ABSTRACT FROM AUTHOR]

Synthetic biohybrid systems by coupling artificial system with nature's machinery may offer a disruptive solution to address the global energy crisis. We developed a versatile electroenzymatic pathway for the continuous synthesis of valuable chemicals, facilitated by formate‐driven NADH regeneration. Utilizing a bismuth electrocatalyst, we achieved stable CO2 reduction to formate with approximately 90 % Faraday efficiency at a current density of 150 mA cm−2. The generated formate acts as a mediator to regenerate NADH, which is then coupled with immobilized redox enzymes—alcohol dehydrogenase (ADH), L‐lactate dehydrogenase (LDH), and L‐glutamate dehydrogenase (GDH)—to produce targeted chemicals at significant rates and exceptionally high turnover numbers (1.8×106 to 3.1×106). These achievements not only underscore the efficiency of the system but also its practical applicability in industrial settings. By leveraging in situ generated formate, this innovative approach demonstrates the potential of integrating electrocatalysis with enzymatic reactions for sustainable and efficient chemical production on a practical scale. [ABSTRACT FROM AUTHOR]

[Display omitted] Production of C 2 chemicals (such as C 2 H 4 , C 2 H 5 OH, etc.) from CO 2 electroreduction reaction (CO 2 ER) has been regarded as a promising route to solve the environmental problems and energy crisis. In this work, mesoporous Cu 2 O microspheres of ca. 700 nm diameter size with low crystallinity were fabricated to enable efficient conversion of CO 2 to C 2 chemicals by electrocatalytic reduction. It is revealed that compared with bulk Cu 2 O, the obtained mesoporous Cu 2 O microspheres have larger surface area, more grain boundaries and defects (unsaturated coordination sites), which facilitate the adsorption and stabilization of the important intermediates, such as *CO, on the route to C 2 chemicals formation. As a result, the Faraday efficiency (FE) of C 2 products reaches as high as 82.6 % and 78.5 % in an H-cell and a flow cell, respectively. In situ Raman and FT-IR spectra reveal that during CO 2 ER test there exists abundant *CO on the mesoporous Cu 2 O surface, thus increasing the opportunity of C C coupling. And the high coverage of *CO on catalyst surface during CO 2 ER protects and stabilizes the oxidation state of Cu species. This work demonstrates an effective strategy to introduce mesoporous structures and decreased crystallinity for improving the performance of CO 2 ER to C 2 products. [ABSTRACT FROM AUTHOR]

The persistent increase in atmospheric carbon dioxide (CO2) concentration poses a significant contemporary challenge. Contemporary chemistry is heavily focused on sustainable solutions, particularly the photo‐/electrocatalytic reduction of CO2 and its utilization for energy storage. Despite promising prospects, efficient chemical CO2 conversion faces obstacles such as ineffective CO2 uptake/activation and catalyst mass transport. Covalent organic frameworks (COFs) have emerged as potential catalysts due to their precise structural design, functionalizable chemical environments, and robust architectures. COF‐based materials, especially those incorporating diverse active sites like single metal sites, metal nanoparticles, and metal oxides, hold promise for CO2 conversion and energy storage. This review sheds light on CO2 photoreduction/electroreduction and storage in Li‐CO2 batteries catalyzed by COF‐based composites, focusing on recent advancements in integrating COFs with nanoparticles for CO2 reduction. It discusses design principles, synthesis methods, and catalytic mechanisms driving the enhanced performance of COF‐based nanocomposites across various applications, including electrochemical reduction, photocatalysis, and lithium CO2 batteries. The review also addresses challenges and prospects of COF‐based catalysts for efficient CO2 utilization, aiming to steer the development of innovative COF‐based nanocomposites, thus advancing sustainable energy technologies and environmental stewardship. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Renewable‐powered electrocatalytic CO2 conversion to long‐chain hydrocarbons represents a sustainable path to produce chemicals and fuels. However, recently discovered systems still lack C–C coupling capabilities required to yield longer, more valuable carbon chains. This study reports cobalt catalysts with a focus on a Co3O4‐derived material for the selective conversion of CO2 to C1–C7 hydrocarbons, following an Anderson–Schulz–Flory distribution. The obtained chain growth probability (α) of 0.54 substantially exceeds that of any other known electrocatalyst, which ranged from 0.2 to 0.4. Detailed in situ characterization and simulations indicated that Co‐Co3O4 interfaces, formed in situ during CO2 electrolysis, are the active sites that promote enhanced chain growth. To prevent overreduction that causes the deactivation of these interfacial sites, the electrode is exposed to intermittent short reoxidation cycles during CO2 electrolysis. Consequently, the catalyst regained its oxidic phase and ability to form hydrocarbons. Overall, this study opens new frontiers in the one‐step conversion of CO2 into multi‐carbon products and suggests the exploration of metal–metal oxide interfaces as a promising strategy for further progress. [ABSTRACT FROM AUTHOR]

Oxide derived catalyst displays outstanding catalytic activity and selectivity in electrochemical carbon dioxide reduction reaction (CO2RR), in which, it is found that residue oxygen atoms play a pivotal role in regulating the catalyst's electronic structure and thus the CO2RR process. Unfortunately, the intrinsic thermodynamic instability of oxygen atoms in oxide derived catalyst under cathodic CO2RR potentials makes it unstable during continuous electrolysis, greatly hindering its practical industrial applications. In this work, we develop a pulsed‐bias technique that is able to dynamically stabilize the residue oxygen atoms in oxide derived catalyst during electrochemical CO2RR. As a result, the oxide derived catalyst under pulsed bias exhibits super catalytic stability in catalyzing electrochemical CO2RR, while keeping excellent catalytic activity and selectivity. [ABSTRACT FROM AUTHOR]

The intensive study of electrochemical CO2 reduction reaction (CO2RR) has resulted in numerous highly selective catalysts, however, most of these still exhibit uncontrollable selectivity. Here, it is reported for the first time the controllable CH4/C2H4 selectivity by modulating the electronic states of Cu incorporated in metal‐organic frameworks with different functional ligands, achieving a Faradaic efficiency of 58% for CH4 on Cu‐incorporated UiO‐66‐H (Ce) composite catalysts, Cu/UiO‐66‐H (Ce) and that of 44% for C2H4 on Cu/UiO‐66‐F (Ce). In situ measurements of Raman and X‐ray absorption spectra revealed that the electron‐withdrawing ability of the ligand side group controls the product selectivity on MOFs through the modulation of the electronic states of Cu. This work opens new prospects for the development of MOFs as a platform for the tailored tuning of selectivity in CO2RR. [ABSTRACT FROM AUTHOR]

Formic acid (HCOOH) is a highly energy efficient product of the electrochemical CO2 reduction reaction (CO2RR). Bismuth‐based catalysts have shown promise in the conversion of CO2 to formic acid, but there is still a great need for further improvement in selectivity and activity. Herein, we report the preparation of Bi nanosheets decorated by cerium oxide nanoparticles (CeOx) with high Ce3+/Ce4+ ratio and rich oxygen vacancies. The CeOx nanoparticles affect the electronic structures of bismuth, enhance CO2 adsorption, and thus promote the CO2RR properties of Bi nanosheets. Compared with elemental Bi nanosheets, the hetero‐structured CeOx/Bi nanosheets exhibit much higher activity over a wide potential window, showing a current density of 16.1 mA cm−2 with a Faradaic efficiency of 91.1% at −0.9 V vs. reversible hydrogen electrode. [ABSTRACT FROM AUTHOR]

The pursuit of high efficacy C−C coupling during the electrochemical CO2 reduction reaction remains a tremendous challenge owing to the high energy barrier of CO2 activation and insufficient coverage of the desired intermediates on catalytic sites. Inspired by the concept of capture‐coupled CO2 activation, we fabricated quinone‐grafted carbon nanofibers via an in situ oxidative carbonylation strategy. The quinone functionality of carbon nanofibers promotes the capture of CO2 followed by activation. At a current density of 400 mA cm−2, the Faradaic efficiency of ethylene reached 62.9 %, and a partial current density of 295 mA cm−2 was achieved on the quinone‐rich carbon nanofibers. The results of in situ spectroscopy and theoretical calculations indicated that the remarkable selectivity enhancement in ethylene originates from the quinone structure, rather than the electronic properties of Cu particles. The interaction of quinone with CO2 increases the local *CO coverage and simultaneously hinders the co‐adsorption of *H on Cu sites, which greatly reduces the energy barrier for C−C coupling and restrains subsequent *CO protonation. The modulation strategy involving specific oxygenated structure, as an independent degree of freedom, guides the design of functionalized carbon materials for tailoring the selectivity of desired products during the CO2 capture and reduction. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 (ERCO2) to valuable chemicals such as acetic acid/acetate offers a promising route to revolutionize chemical production and enhance sustainability. Here, we report the hydrothermal preparation of an electrocatalyst consisting of copper/titanium dioxide/reduced graphene oxide (Cu‐TiO2/rGO) for ERCO2 in aqueous medium. The metal‐support (TiO2/rGO) was pre‐synthesized by combining an aqueous solution of TiO2 and GO in an autoclave at 150 °C for 20 h. Then TiO2/rGO was added to synthesized Cu colloid formed through the reduction of copper (II) nitrate trihydrate resulting in the formation of Cu‐TiO2/rGO. The Cu‐TiO2/rGO hybrid nanocomposite was fully characterized using spectroscopic and microscopic techniques. This study explored the versatility of the rotating ring‐disc electrode (RRDE) as an in situ electroanalytical tool for the selective detection of products formed during ERCO2. The well‐designed hybrid electrocatalyst, containing Cu0/Cu+ active sites, facilitated the eight‐electron transfer for acetic acid (AA) formation at low potentials. AA formation was detected on the RRDE and validated by conventional NMR and HPLC techniques. This work highlights and expands the scope of selective hydrogenation of CO2 towards value‐added products. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of CO2 into high energy‐density fuels and value‐added chemicals under mild conditions can promote the sustainable cycle of carbon and decrease current energy and environmental problems. Constructing electrocatalyst with high activity, selectivity, stability, and low cost is really matter to realize industrial application of electrocatalytic CO2 reduction (ECR). Metal–nitrogen–carbon (M–N–C), especially Ni–N–C, display excellent performance, such as nearly 100% CO selectivity, high current density, outstanding tolerance, etc., which is considered to possess broad application prospects. Based on the current research status, starting from the mechanism of ECR and the existence form of Ni active species, the latest research progress of Ni–N–C electrocatalysts in CO2 electroreduction is systematically summarized. An overview is emphatically interpreted on the regulatory strategies for activity optimization over Ni–N–C, including N coordination modulation, vacancy defects construction, morphology design, surface modification, heteroatom activation, and bimetallic cooperation. Finally, some urgent problems and future prospects on designing Ni–N–C catalysts for ECR are discussed. This review aims to provide the guidance for the design and development of Ni–N–C catalysts with practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu clusters with the diameter of ∼1.0 nm was fabricated and coordinated with B, N atoms in porous carbon matrix. • The catalyst showed stable 70 % FE under 20.8 mA cm−2 during 12 h testing in CO 2 RR to formate. • The overall catalytic performance of Cu/BN-C was superior to other Cu-based catalysts. • DFT revealed the synergy between Cu clusters and B, N by enhancing the charge density of Cu. • This research highlighted the importance of synergistic effects of Cu size effect and heteroatoms coordination. Electrochemical CO 2 conversion into formate by intermittent renewable electricity, presents a captivating prospect for both the storage of renewable electrical energy and the utilization of emitted CO 2. Typically, Cu-based catalysts in CO 2 reduction reactions favor the production of CO and other by-products. However, we have shifted this selectivity by incorporating B, N co-doped carbon (BNC) in the fabrication of Cu clusters. These Cu clusters are regulated with B, N atoms in a porous carbon matrix (Cu/BN-C), and Zn2+ ions were added to achieve Cu clusters with the diameter size of ∼1.0 nm. The obtained Cu/BN-C possesses a significantly improved catalytic performance in CO 2 reduction to formate with a Faradaic efficiency (FE) of up to 70 % and partial current density (j formate) surpassing 20.8 mA cm−2 at −1.0 V vs RHE. The high FE and j formate are maintained over a 12-hour. The overall catalytic performance of Cu/BN-C outperforms those of the other investigated catalysts. Based on the density functional theory (DFT) calculation, the exceptional catalytic behavior is attributed to the synergistic effect between Cu clusters and N, B atoms by modulating the electronic structure and enhancing the charge transfer properties, which promoted a preferential adsorption of HCOO* over COOH*, favoring formate formation. [ABSTRACT FROM AUTHOR]

CO2 electroreduction reaction (CO2ER) provides a promising pathway for scaling up the conversion of CO2 to CO using renewable electricity, thereby providing an alternative potential pathway to carbon neutrality. Typically, the reaction conducted in aqueous media is an ideal way on the standpoint of sustainability. However, the undesired hydrogen evolution reaction (HER) is feasible to occur on catalyst surface together with CO2ER, thereby reducing the overall CO2‐to‐CO efficiency. In this work, we utilized the stacked structure of N‐doped Ti3C2Tx MXene material supported metal oxide (ZnO) to form a ZnO/N‐Ti3C2Tx catalyst in electrolytic CO2 reduction to CO. The catalyst exhibited an Faradaic efficiency (FECO) of 96.4 % in CO2ER at −0.967 V (vs. RHE) with a current density of 7.2 mA cm−2. ZnO acted as the active site for CO2ER in ZnO/N‐Ti3C2Tx, while N‐doped Ti3C2Tx MXene was responsible for enhancing textural properties and electrical conductivity, which could promote the mass transfer of gas molecules and electron transfer to ZnO active sites, and further improving the activity. This work inspires the rational design of unique metal oxide/N‐Ti3C2Tx interfaces to regulate the high‐performance electrocatalytic selectivity of CO2 reduction. [ABSTRACT FROM AUTHOR]

It is widely established that the electroreduction of carbon dioxide on a copper surface yields a spectrum of alcohols and hydrocarbons. But the selectivity of Cu toward a certain product is extremely poor as it forms a variety of reduced products concurrently. Controlling selectivity and overall performance depends on the modification of the Cu site and local environment. This study depicts how the product selectivity can be switched from C1 to C2 and multicarbon products by systematic incorporation of secondary metal (Pd) into the Cu lattice. Upon releasing the structural ordering from intermetallic to alloy and then to bimetallic, a systematic enhancement on the formation of C2 products from CO2 has been observed. Real‐time in situ X‐ray absorption spectroscopy (XAS) study showed the potential dependent evolution of Pd─Cu and Cu─Cu bonds in different Pd‐Cu‐based catalysts. The detailed analysis of in situ IR and Raman also determined the adsorbed intermediate species and helped to identify the mechanism. Computational studies show the feasibility of multicarbon product formation on bimetallic catalysts compared to alloy and intermetallic catalysts. The current density and the activity of the CO2 electroreduction have been enhanced by the utilization of the flow cell in the gas diffusion electrode configuration. [ABSTRACT FROM AUTHOR]

Metal–N–C single‐atom catalysts, mostly prepared from pyrolysis of metal‐organic precursors, are widely used in heterogeneous electrocatalysis. Since metal sites with diverse local structures coexist in this type of material and it is challenging to characterize the local structure, a reliable structure–property relationship is difficult to establish. Conjugated macrocyclic complexes adsorbed on carbon support are well‐defined models to mimic the single‐atom catalysts. Metal–N4 site with four electroneutral pyridine‐type ligands embedded in a graphene layer is the most commonly proposed structure of the active site of single‐atom catalysts, but its molecular counterpart has not been reported. In this work, we synthesized the conjugated macrocyclic complexes with a metal center (Co, Fe, or Ni) coordinated with four electroneutral pyridinic ligands as model catalysts for CO2 electroreduction. For comparison, the complexes with anionic quadri‐pyridine macrocyclic ligand were also prepared. The Co complex with the electroneutral ligand expressed a turnover frequency of CO formation more than an order of magnitude higher than that of the Co complex with the anionic ligand. Constrained ab initio molecular dynamics simulations based on the well‐defined structures of the model catalysts indicate that the Co complex with the electroneutral ligand possesses a stronger ability to mediate electron transfer from carbon to CO2. [ABSTRACT FROM AUTHOR]

Various electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical CO2 reduction reaction (CO2RR). However, an efficient CO2RR electrocatalyst doesn't ensure an effective co‐catalyst on the semiconductor surface for photoelectrochemical CO2RR. Herein, Bi2S3 nanorods are synthesized and electrochemically reduced to Bi nanoplates that adhere to the substrates for application in the electrochemical and photoelectrochemical CO2RR. Compared with commercial‐Bi, the Bi2S3‐derived Bi (S‐Bi) nanoplates on carbon paper exhibit superior electrocatalytic activity and selectivity for formate (HCOO−) in the electrochemical CO2RR, achieving a Faradaic efficiency exceeding 93%, with minimal H2 production over a wide potential range. This highly selective S‐Bi catalyst is being employed on the Si photocathode to investigate the behavior of electrocatalysts during photoelectrochemical CO2RR. The strong adhesion of the S‐Bi nanoplates to the Si nanowire substrate and their unique catalytic properties afford exceptional activity and selectivity for HCOO− under simulated solar irradiation. The selectivity observed in electrochemical CO2RR using the S‐Bi catalyst correlates with that seen in the photoelectrochemical CO2RR system. Combined pulsed potential methods and theoretical analyses reveal stabilization of the OCHO* intermediate on the S‐Bi catalyst under specific conditions, which is critical for developing efficient catalysts for CO2‐to‐HCOO− conversion. [ABSTRACT FROM AUTHOR]

Developing highly efficient catalysts for carbon dioxide reduction reaction (CO2RR) is significant in producing useful chemicals and alleviating environmental pollution. Herein, a series of two-dimensional TM-PTC (TM = Sc-Zn, PTC = 1,2,3,4,5,6,7,8,9,10,11,12-perthiolated coronene) frameworks as CO2RR electrocatalysts are investigated based on the density functional method. The calculated results showed that the main product is CH4 for TM-PTC (TM = Sc-Mn). However, these catalysts can be poisoned by water molecules due to its strong adsorption on the catalyst surface. To solve the problem, we modified these catalysts by adding axial oxygen (TM-O-PTC). Our study showed that TM-O-PTC (TM = V, Cr) are good catalysts for CO2RR to produce CH4. We expected that this work could provide a useful strategy for developing high-performance CO2RR electrocatalysts. [ABSTRACT FROM AUTHOR]

Microenvironment regulation of M‐N4 single‐atom catalysts (SACs) is a promising way to tune their catalytic properties toward the electrochemical CO2 reduction reaction. However, strategies that can effectively introduce functional groups around the M‐N4 sites through strong covalent bonding and under mild reaction conditions are highly desired. Taking the hydrophilic Ni‐N4 SAC as a representative, we report herein a [2+1] cycloaddition reaction between Ni‐N4 and in situ generated difluorocarbene (F2C:), and enable the surface fluorocarbonation of Ni‐N4, resulting in the formation of a super‐hydrophobic Ni‐N4‐CF2 catalyst. Meanwhile, the mild reaction conditions allow Ni‐N4‐CF2 to inherit both the electronic and structural configuration of the Ni‐N4 sites from Ni‐N4. Enhanced electrochemical CO2‐to‐CO Faradaic efficiency above 98 % is achieved in a wide operating potential window from −0.7 V to −1.3 V over Ni‐N4‐CF2. In situ spectroelectrochemical studies reveal that a highly hydrophobic microenvironment formed by the −CF2− group repels asymmetric H‐bonded water at the electrified interface, inhibiting the hydrogen evolution reaction and promoting CO production. This work highlights the advantages of [2+1] cycloaddition reactions on the covalent modification of N‐doped carbon‐supported catalysts. [ABSTRACT FROM AUTHOR]

Copper (Cu) is the most attractive electrocatalyst for CO2 reduction to multi‐carbon (C2+) products with high economic value in considerable amounts. However, the rational design of a structurally stable Cu‐based catalyst that can achieve high activity and stability towards C2+ products remain a grand challenge. Here, a highly stable nickel oxygenate/Cu electrocatalyst is developed with abundant NiOOH/Cu interfaces by in situ electrochemical reconstruction. The nickel oxygenate/Cu electrocatalyst achieves a superior Faradaic efficiency of 86.3 ± 3.0% and a record partial current density of 2085 A g−1 for C2+ products with long‐term stability. In situ experimental and theoretical studies demonstrates that the exceptional performance in generating C2+ products is attributed to the presence of the NiOOH/Cu interfaces which increase *CO coverage, lower energy barrier for *CO coupling and stabilize *OCCO simultaneously. This work provides new insights into the rational design of electrocatalysts to achieve stable and efficient electrocatalytic CO2 reduction capabilities. [ABSTRACT FROM AUTHOR]

Pb SA -Cu/PC with a three-dimensional structure was demonstrated as an efficient CO 2 reduction catalyst to formate. Pb inhibited the formation of COOH*, reduced the energy barrier of rate determining step in the formate formation process, and achieved 97% high formate selectivity. [Display omitted] • Pb SA100 -Cu/CP catalyst is developed by an economical and low-energy method. • The FE formate is 97 % with a partial current density of 27.9 mA cm−2 at − 0.9 V. • The catalyst exhibits ultra-long stability for more than 60 h. • The synergistic action of Pb SA and Cu atoms lowers the RDS for CO 2 RR to fromate. • Single-atom Pb induces Cu charge redistribution and inhibits the formation of COOH*. Exploring highly selective and stable electrocatalysts is of great significance for the electrochemical conversion of CO 2 into fuel. Herein, a three-dimensional (3D) nanostructure catalyst was developed by doping Pb single-atom (Pb SA) in-situ on carbon paper (Pb SA100 -Cu/CP) through a low-energy and economical method. The designed catalyst exhibited abundant active sites and was beneficial to CO 2 adsorption, activation, and subsequent conversion to fuel. Interestingly, Pb SA100 -Cu/CP showed a prominent Faraday efficiency (FE) of 97 % at –0.9 V versus reversible hydrogen electrode (vs. RHE) and a high partial current density of 27.9 mA·cm−2 for formate. Also, the catalyst remained significantly stable for 60 h during the durability test. The reaction mechanism was investigated by density functional theory (DFT), demonstrating that the doping Pb SA induced the electrons redistribution, promoted the formate generation, reduced the rate-determining step (RDS) energy barrier, and inhibited the hydrogen evolution reaction. The study aims to provide a new strategy for developing of single-atom catalysts with high selectivity and stability, which will help reduce environmental pressure and alleviate energy problems. [ABSTRACT FROM AUTHOR]

Copper‐based bimetallic heterojunction catalysts facilitate the deep electrochemical reduction of CO2 (eCO2RR) to produce high‐value‐added organic compounds, which hold significant promise. Understanding the influence of copper interactions with other metals on the adsorption strength of various intermediates is crucial as it directly impacts the reaction selectivity. In this review, an overview of the formation mechanism of various catalytic products in eCO2RR is provided and highlight the uniqueness of copper‐based catalysts. By considering the different metals' adsorption tendencies toward various reaction intermediates, metals are classified, including copper, into four categories. The significance and advantages of constructing bimetallic heterojunction catalysts are then discussed and delve into the research findings and current development status of different types of copper‐based bimetallic heterojunction catalysts. Finally, insights are offered into the design strategies for future high‐performance electrocatalysts, aiming to contribute to the development of eCO2RR to multi‐carbon fuels with high selectivity. [ABSTRACT FROM AUTHOR]

Despite of high conductivity and reducing ability, transition metal nanoparticles tend to aggregate and unavoidably impact the selectivity during the proton‐coupled reduction process of CO2RR. New strategy to regulate and utilize the electronic property of transition‐metal particles allows for effective tuning of eCO2RR activity. Through simple creation of N‐doped carbon shells surrounding Ni nanoparticles and controlling the amount and arrangement of the N atoms, successful and long‐lasting electrochemical reduction of CO2 was accomplished. The inherent HER activity was almost completely suppressed. It exhibited FECO above 90 % in a 500 mV potential window, with the optimal up to 96.5 % at −0.78 V vs RHE. In flow cell electrolysis, a current density of 289.4 mA/cm2 was achieved with Faradic efficiency of 96.4 % towards CO. The results of control experiments using different catalysts imply that electron transfer between Ni core and shells was significantly influenced by the property of N atoms. High content of graphitic nitrogen is crucial for the catalytic performance. [ABSTRACT FROM AUTHOR]

A series of twelve second coordination sphere (SCS) functionalized manganese tricarbonyl bipyridyl complexes are investigated for their electrocatalytic CO2 reduction properties in acetonitrile. A qualitative and quantitative assessment of the SCS functional groups is discussed with respect to the catalysts' thermodynamic and kinetic efficiencies, and their product selectivities. In probing a broad scope of functional groups, it is clear that only the aprotic ortho‐arylester SCS is capable of promoting the highly desired low‐overpotential proton‐transfer electron‐transfer (PT‐ET) pathway for selective CO production. The ortho‐phenolic analogues cause an increase in overpotential with a product selectivity favoring H2 evolution, consistent with a high‐overpotential pathway via the anionic [Mn−H]− intermediate. Alternative aprotic Lewis base functional groups such as trifluoromethyl, morpholine and acetamide are shown to also be capable of intermediate manganese hydride generation. The tertiary amine substituent, 2‐morpholinophenyl, exhibits a desirable product distribution characteristic of syn‐gas (CO : H2=30 : 48) with an impressive turnover frequency, while the secondary amine group, 2‐acetamidophenyl, induces a notable shift in selectivity with a faradaic yield of 55 % for the formate (HCO2−) product. In addition to their catalytic properties, cyclic voltammetry and infrared spectroelectrochemistry (IR‐SEC) studies are presented to probe pre‐catalyst electronic properties and the two‐electron reduction activation pathway. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 to multi‐carbon products is an attractive strategy to achieve a carbon‐neutral energy cycle. Single‐atom catalysts (SACs) that achieve the C2 selectivity always have low metal loading and inevitably undergo in situ reversible/irreversible metallic agglomerations under working conditions. Herein, a high‐density Cu SA anchored F, O, N co‐doped carbon composites (CuFONC) with a stable CuN2O1 configuration is provided, which can reach a remarkable C2 selectivity of ≈80.5% in Faradaic efficiency at −1.3 V versus RHE. In situ/ex situ experimental characterization and density functional theory (DFT) calculations verified that the excellent stability of CuN2O1 during the CO2RR process can be attributed to F/O co‐derived regulation for CuFONC. Remarkably, as confirmed by DFT, it is atomic Cu sites and the adjacent bonded N motifs in CuFONC that act as the adsorption sites for CO* during the C─C coupling process. This work brings a prospective on designing novel but stable atomic Cu coordination for electrolytic CO2‐to‐C2 pathway. [ABSTRACT FROM AUTHOR]

Double-site catalysts have attracted widespread attention in the field of electrocatalysis due to their high metal loading, adjustable active centres, and electronic valence states. However, the development of bimetallic sites catalysts that coordinate with definite atoms is still in the exploratory stage. Here, we designed and synthesized a bimetallic palladium complex (BPB-Pd2) with conjugated backbone. The supported BPB-Pd2 was applied to electrochemical CO2 reduction reaction (CO2RR) for the first time. The as-obtained BPB-Pd2 gives an exceptional Faradaic efficiency of CO (FECO) of 94.4% at −0.80 V vs. reversible hydrogen electrode (RHE), which is significantly superior to monoatomic palladium catalyst (BPB-Pd1). The density functional theory (DFT) calculations revealed that the essential reason for the outstanding activity of BPB-Pd2 toward CO2RR was that the electronic effect between diatomic palladium reduces the free energy change for CO2RR process. Thus, BPB-Pd2 exhibits moderate free energy change to form COOH* intermediate, which was beneficial for the generation of CO in CO2RR. [ABSTRACT FROM AUTHOR]

The drastic climate change imposing adverse environmental effects receives serious research attention for finding a suitable solution. The replacement of conventional fossil energy sources with renewable and sustainable energy sources is the potential route; and thus, manifests as a viable solution. Accordingly, the electrocatalytic carbon dioxide (CO2) reduction process coupled with the renewable energy source is an emerging strategy for adopting a sustainable approach. However, the existing challenges in designing suitable catalyst, support material, electrolyte, inadequate selectivity, and intermediate reactions of CO2 reduction demand substantial research advancement. Numerous studies reported for the CO2 reduction process highlight the importance of catalyst design and product selectivity. Importantly, the copper‐based catalysts, capable in the output of multi‐carbon products, are reported as a "star" material. This review; therefore, focuses on catalyst design strategies, unique structural/morphological features, and product selectivity of diverse copper‐based catalysts. The outstanding findings of copper‐based catalysts and the corresponding products are critically discussed with adequate figures of merits. The impact of structural/morphological features on product selectivity is discussed in detail. The future scope and author perspectives on copper‐based catalysts for the feasible electrocatalytic CO2 reduction application are summarized. [ABSTRACT FROM AUTHOR]

Copper (Cu) has been regarded as a highly efficient electrocatalyst for the conversion of CO2 into a multicarbon product. However, the catalytic mechanism and the active sites of Cu catalysts under operating conditions still remain elusive. Yang's team applied systematic operando characterization techniques to provide a quantitative analysis of the valence states and the chemical environment of Cu nanocatalysts under electrochemical reaction conditions, which clearly reveal the evolution of Cu nanocatalysts before and after the entire electrochemical CO2 reduction. [ABSTRACT FROM AUTHOR]

New mechanism to understand the role of oxygen-containing species in promoting the production of C 2+ products via CO 2 RR. [Display omitted] Oxygen-containing species have been demonstrated to play a key role in facilitating electrocatalytic CO 2 reduction (CO 2 RR), particularly in enhancing the selectivity towards multi-carbon (C 2+) products. However, the underlying promotion mechanism is still under debate, which greatly limits the rational optimization of the catalytic performance of CO 2 RR. Herein, taking CO 2 and O 2 co-electrolysis over Cu as the prototype, we successfully clarified how O 2 boosts CO 2 RR from a new perspective by employing comprehensive theoretical simulations. Our results demonstrated that O 2 in feed gas can be rapidly reduced into *OH, leading to the partial oxidation of Cu surface under reduction conditions. Surface *OH accelerates the formation of quasi-specifically adsorbed K+ due to the electrostatic interaction between *OH and K+ ions, which significantly increases the concentration of K+ near the Cu surface. These quasi-specifically adsorbed K+ ions can not only lower the C–C coupling barriers but also promote the hydrogenation of CO 2 to improve the CO yield rate, which are responsible for the remarkably enhanced efficiency of C 2+ products. During the whole process, O 2 co-electrolysis plays an indispensable role in stabilizing surface *OH. This mechanism can be also adopted to understand the effect of high pH of electrolyte and residual O in oxide-derived Cu (OD-Cu) on the catalytic efficiency towards C 2+ products. Therefore, our work provides new insights into strategies for improving C 2+ products on the Cu-based catalysts, i.e., maintaining partial oxidation of surface under reduction conditions. [ABSTRACT FROM AUTHOR]

The reduction of carbon dioxide (CO2) using porphyrin‐containing 2D covalent organic frameworks (2D‐COFs) catalysts is widely explored nowadays. While these framework materials are normally fabricated as powders followed by their uncontrolled surface heterogenization or directly grown as thin films (thickness >200 nm), very little is known about the performance of substrate‐supported single‐layered (≈0.5 nm thickness) 2D‐COFs films (s2D‐COFs) due to its highly challenging synthesis and characterization protocols. In this work, a fast and straightforward fabrication method of porphyrin‐containing s2D‐COFs is demonstrated, which allows their extensive high‐resolution visualization via scanning tunneling microscopy (STM) in liquid conditions with the support of STM simulations. The as‐prepared single‐layered film is then employed as a cathode for the electrochemical reduction of CO2. Fe porphyrin‐containing s2D‐COF@graphite used as a single‐layered heterogeneous catalyst provided moderate‐to‐high carbon monoxide selectivity (82%) and partial CO current density (5.1 mA cm−2). This work establishes the value of using single‐layered films as heterogene ous catalysts and demonstrates the possibility of achieving high performance in CO2 reduction even with extremely low catalyst loadings. [ABSTRACT FROM AUTHOR]

Molybdenum‐ or tungsten‐dependent formate dehydrogenases have emerged as significant catalysts for the chemical reduction of CO2 to formate, with biotechnological applications envisaged in climate‐change mitigation. The role of Met405 in the active site of Desulfovibrio vulgaris formate dehydrogenase AB (DvFdhAB) has remained elusive. However, its proximity to the metal site and the conformational change that it undergoes between the resting and active forms suggests a functional role. In this work, the M405S variant was engineered, which allowed the active‐site geometry in the absence of methionine Sδ interactions with the metal site to be revealed and the role of Met405 in catalysis to be probed. This variant displayed reduced activity in both formate oxidation and CO2 reduction, together with an increased sensitivity to oxygen inactivation. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochemical reduction of CO 2 (CO 2 RR) to fuels and chemicals is a promising route to close the anthropogenic carbon cycle for sustainable society. The Cu-based catalysts in producing high-value hydrocarbons feature unique superiorities, yet challenges remain in achieving high selectivity. In this work, Cu@ZIF-8 NWs with highly-exposed Cu nanowires (Cu NWs) and ZIF-8 interface are synthesized via a surfactant-assisted method. Impressively, Cu@ZIF-8 NWs exhibit excellent stability and a high Faradaic efficiency of 57.5% toward hydrocarbons (CH 4 and C 2 H 4) at a potential of −0.7 V versus reversible hydrogen electrode. Computational calculations combining with experiments reveal the formation of Cu and ZIF-8 interface optimizes the adsorption of reaction intermediates, particularly stabilizing the formation of *CHO, thereby enabling efficient preference for hydrocarbons. This work highlights the potential of constructing metals and MOFs heterogeneous interfaces to enhance catalytic properties and offers valuable insights for the design of highly efficient CO 2 RR catalysts. [ABSTRACT FROM AUTHOR]

This study presents a green method of producing copper nanoparticles (CuNPs) using aqueous extracts from Sargassum spp. as reducing, stabilizing, and capping agents. The CuNPs created using this algae‐based method are not hazardous, they are eco‐friendly, and less toxic than their chemically synthesized counterparts. The XRD characterization of the CuNPs revealed the presence of Cu and CuO, with a crystallite size ranging from 13 to 17 nm. Following this, the CuNPs were supported onto a carbon substrate, also derived from Sargassum spp. (biochar CSKPH). The CuNPs in biochar (CuNPs‐CSKPH) did not appear in the XRD diffractograms, but the SEM‐EDS results showed that they accounted for 36 % of the copper weight. The voltamperometric study of CuNps‐CSKPH in acid media validated the presence of Cu and the amount was determined to be 2.58 μg. The catalytic activity of CuNPs‐CSKPH was analyzed for the electrochemical reduction of CO2. The use of Sargassum spp. has great potential to tackle two environmental problems simultaneously, by using it as raw material for the synthesis of activated biochar as support, as well as the synthesis of CuNPs, and secondly, by using it as a sustainable material for the electrochemical conversion of CO2. [ABSTRACT FROM AUTHOR]

This study presents a green method of producing copper nanoparticles (CuNPs) using aqueous extracts from Sargassum spp. as reducing, stabilizing, and capping agents. The CuNPs created using this algae‐based method are not hazardous, they are eco‐friendly, and less toxic than their chemically synthesized counterparts. The XRD characterization of the CuNPs revealed the presence of Cu and CuO, with a crystallite size ranging from 13 to 17 nm. Following this, the CuNPs were supported onto a carbon substrate, also derived from Sargassum spp. (biochar CSKPH). The CuNPs in biochar (CuNPs‐CSKPH) did not appear in the XRD diffractograms, but the SEM‐EDS results showed that they accounted for 36 % of the copper weight. The voltamperometric study of CuNps‐CSKPH in acid media validated the presence of Cu and the amount was determined to be 2.58 μg. The catalytic activity of CuNPs‐CSKPH was analyzed for the electrochemical reduction of CO2. The use of Sargassum spp. has great potential to tackle two environmental problems simultaneously, by using it as raw material for the synthesis of activated biochar as support, as well as the synthesis of CuNPs, and secondly, by using it as a sustainable material for the electrochemical conversion of CO2. [ABSTRACT FROM AUTHOR]

Based on our previous study in chemical subtleties of the proton tunneling distance for metal hydride formation (PTD‐MH) to regulate the selectivity of CO2 reduction reaction (CO2RR), we have developed a family of Mn terpyridine derivatives, in which urea groups functions as multipoint hydrogen‐bonding hangman to accelerate the reaction rate. We found that such changes to the second coordination sphere significantly increased the turnover frequency (TOF) for CO2 reduction to ca. 360 s-1 ${{s}^{-1}}$ with this family of molecular catalysts while maintaining high selectivity (ca. 100 %±3) for CO even in the presence of a large amount of phenol as proton source. Notably, the compounds studied in this manuscript all exhibit large value for icat/ip ${{{\bf i}}_{{\bf c a t}}/{{\bf i}}_{{\bf p}}}$ as that achieved by Fe porphyrins derivates, while saving up to 0.55 V in overpotential with respect to the latter. [ABSTRACT FROM AUTHOR]

Important improvements have been achieved in developing the coupling of electrochemical CO2 reduction to formate with its subsequent microbial conversion to polyhydroxybutyrate (PHB) by Cupriavidus necator. The CO2 based formate electrosynthesis was optimised by electrolysis parameter adjustment and application of Sn based gas diffusion electrodes reaching almost 80 % Faradaic efficiency at 150 mA cm−2. Thereby, catholyte with the high formate concentration of 441±9 mmol L−1 was generated as feedstock without intermediate downstream processing for semi‐automated formate feeding into a fed‐batch reactor system. Moreover, microbial formate conversion to PHB was studied further, optimised, and successfully scaled from shake flasks to semi‐automated bioreactors. Therein, a PHB per formate ratio of 16.5±4.0 mg g−1 and a PHB synthesis rate of 8.4±2.1 mg L−1 OD−1 h−1 were achieved. By this process combination, an almost doubled overall process yield of 22.3±5.5 % was achieved compared to previous reports. The findings allow a detailed evaluation of the overall CO2 to PHB conversion, providing the basis for potential technical exploitation. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts possess great potential for applications in electrochemical carbon dioxide reduction reactions. Recently, the fast and low‐cost preparation of highly efficient single‐atom catalysts remains a challenge. Herein, a high‐density current generated by pulsed discharge is employed for the formation of graphene aerogel anchored Cu single atom catalysts perfectly. The Cu atoms decomposed by Cu(NO3)2•xH2O are fixed on graphene under the local transient high temperature and intense electromagnetic field. The activity and selectivity of formic acid are correlated with the coordinatively unsaturated Cu─N1O1 moieties, reaching an optimal Faradaic efficiency (93.7%) at −0.9 V versus a reversible hydrogen electrode (RHE). In situ characterizations reveal that the asymmetric Cu─N/O structure in a pinched state displays better catalytic activity in CO2RR. Density functional theory results indicate that the Cu─N1O1 sites regulate the adsorption configuration of intermediates and lower the energy barrier for the hydrogenation of *OCHO species, thereby promoting CO2‐to‐HCOOH conversion. [ABSTRACT FROM AUTHOR]

Rising carbon dioxide (CO2) levels in the atmosphere are recognized as a threat to atmospheric stability and life. Although this greenhouse gas is being produced on a large scale, there are solutions to reduction and indeed utilization of the gas. Many of these solutions involve costly or unstable technologies, such as air‐sensitive metal–organic frameworks (MOFs) for CO2 capture or "non‐green" systems such as amine scrubbing. Conjugated microporous polymers (CMPs) represent a simpler, cheaper, and greener solution to CO2 capture and utilization. They are often easy to synthesize at scale (a one pot reaction in many cases), chemically and thermally stable (especially in comparison with their MOF and covalent organic framework (COF) counterparts, owing to their amorphous nature), and, as a result, cheap to manufacture. Furthermore, their large surface areas, tunable porous frameworks and chemical structures mean they are reported as highly efficient CO2 capture motifs. In addition, they provide a dual pathway to utilize captured CO2 via chemical conversion or electrochemical reduction into industrially valuable products. Recent studies show that all these attractive properties can be realized in metal‐free CMPs, presenting a truly green option. The promising results in these two fields of CMP applications are reviewed and explored here. [ABSTRACT FROM AUTHOR]

Design tactics and mechanistic studies both remain as fundamental challenges during the exploitations of earth-abundant molecular electrocatalysts for CO2 reduction, especially for the rarely studied Cr-based ones. Herein, a quaterpyridyl CrIII catalyst is found to be highly active for CO2 electroreduction to CO with 99.8% Faradaic efficiency in DMF/phenol medium. A nearly one order of magnitude higher turnover frequency (86.6 s-1) over the documented Cr-based catalysts (<10 s-1) can be achieved at an applied overpotential of only 190 mV which is generally 300 mV lower than these precedents. Such a high performance at this low driving force originates from the metal-ligand cooperativity that stabilizes the low-valent intermediates and serves as an efficient electron reservoir. Moreover, a synergy of electrochemistry, spectroelectrochemistry, electron paramagnetic resonance, and quantum chemical calculations allows to characterize the key CrII, CrI, Cr0, and CO-bound Cr0 intermediates as well as to verify the catalytic mechanism. [ABSTRACT FROM AUTHOR]