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A naturally occurring water‐soluble cobalt‐complex cyanocobalamin (Vitamin B12) has been identified as a new and efficient electrocatalyst for the CO2‐to‐CO reduction reaction in aqueous solution. Heterogeneous B12‐electrocatalysts prepared by a simple electrochemical immobilization technique on graphene‐oxide (GO)‐modified glassy carbon and carbon paper (CP) electrodes, without any non‐degradable polymer‐binders, showed a highly stable and well‐defined surface‐confined redox peak at E'=−0.138 V vs. RHE with a surface‐excess value, ΓB12=4.28 nmol cm−2. This new electrocatalyst exhibits 93 % Faradaic efficiency for CO2‐to‐CO conversion at an electrolysis potential, −0.882 V vs. RHE (an optimal condition) with a high current density, 29.4 mA cm−2 and turn‐over‐frequency value, 5.2 s−1, without any surface‐fouling problem, in 0.5 m KHCO3. In further, it follows an eco‐friendly, sustainable and water‐based approach with the involvement of biodegradable and non‐toxic chemicals/materials like B12, GO and CP. [ABSTRACT FROM AUTHOR]

• Dendritic In-doped Cu@Cu 2 O catalyst is prepared by co-electrodeposition method. • Doped-In content can tailor Cu+/Cu0 ratio, charge distribution, morphology and ECSA. • Cu+/Cu0 ratio plays a vital role on enhancing FE CO and partial current density at low In doping. • 3.7% In-Cu sample shows the highest FE CO of 87.6 ± 2.2 % and j CO of 9.7 ± 1.04 mA cm -2. Element doping is an effective strategy to enhance the selectivity of electrochemical carbon dioxide reduction. In this work, a dendritic core-shell In-doped Cu@Cu 2 O catalyst is prepared by co-electrodeposition method on carbon fiber paper for selective electroreduction of CO 2 to CO. Faradaic efficiency of producing CO over this dendritic In-doped Cu@Cu 2 O reaches 87.6 ± 2.2% with total current density of 11.1 ± 0.85 mA cm−2 at −0.8 V vs RHE, which outperforms most of the reported Cu-based electrocatalysts. The excellent performance is mainly derived from charge re-distribution and the enhanced intrinsic activity due to the formation of In-doped Cu 2 O layer. Meanwhile, the Cu+/Cu0 can be adjusted by tailoring the doped-In content. The relatively high ECSA and small charge transfer resistance are also conducive to improve the selectivity and activity. The oxyphilic In metal incorporated into the copper lattice can well stabilize the intermediate *COOH through enhancing interaction with O-ends of *COOH. This work provides a facile approach and a deep insight on design and synthesis of high efficiency hybrid electrocatalysts. [ABSTRACT FROM AUTHOR]

Reducing the use of fossil fuels is critical to human society. In recent years, electrocatalytic carbon dioxide (CO2) reduction has attracted widespread attention. A suitable CO2 reduction catalyst is essential to convert CO2 into more valuable chemical products with high selectivity and efficiency. In this paper, a highly selective ZnAlCe-Ternary metal hydroxides (ZnAlCe-THs) nanocomposite electrocatalyst material was designed and prepared, and its performance as an electrocatalyst for catalytic reduction of CO2 to carbon monoxide (CO) was explored. The layered structure of ZnAlCe-THs nanocomposites facilitates electron transfer as well as CO2 and proton transfer, providing a high specific surface area for the electroactive sites of the electrocatalytic reduction reaction. At the same time, the ZnAlCe-THs catalyst generates CO at an overpotential of − 0.5 V. At − 1.2 V versus the reversible hydrogen electrode (vs. RHE), the bias current density is about 10.46 mA cm−2 with high selectivity of 89.3% Faraday efficiency. Its excellent electrochemical properties make it a good catalyst for the selective reduction of CO2 to CO. In this paper, ZnAlCe-Ternary mental hydroxides (ZnAlCe-THs) with a layered hydrotalclike structure were prepared by hydrothermal and co-precipitation methods. It showed excellent catalytic performance in the electrocatalytic reduction of carbon dioxide to carbon monoxide with a Faraday efficiency of 89.3% at − 1.2 V vs. RHE and a current density of 10.46 mA cm−2 for higher selectivity for CO. In addition, the ZnAlCe-THs catalyst is stable and it can operate for 5 h without particularly significant deactivation. [ABSTRACT FROM AUTHOR]

Renewable energy resources (wind, solar) are unpredictable, so it is wise to store the electricity they generate in an energy carrier X. Various PtX (power to useful energy-intensive raw material such as hydrogen, synthetic natural gas, fuel) applications have been proposed. At the heart of our work is widely used idea to convert residual CO2 from biogas plant into higher hydrocarbons using electricity from renewables (e.g., sun, wind, hydro). The specific goal is to produce ethylene-highly demanded hydrocarbon in plastics industry. The process itself is realised on electrocatalytic carbon/copper cathode which must be selective to reaction: 2CO2 + 12e− + 12H+→C2H4 + 4H2O. We propose a bottom-up approach to build catalyst from the smallest particles-graphene sheet stacks (GSS) coated with metallic copper nanocrystals. Composite GSS-Cu structure functions as a CO2 and proton absorber, facilitating hydrogenation and carbon–carbon coupling reactions on Cu-nanocluster/GSS for the formation of C2H4. In our design electrocatalytic electrode is made from nitrogen-doped graphene sheet stacks coated with copper nanostructures. The N-GSSitself can be drop-casted or electrophoretically incorporated onto the carbon paper and gas diffusion electrode. Electrochemical deposition method was recognized as successful and most promising to grow Cu nanocrystals on N-GSS incorporated in conducting carbon substrate. Gaseous products from CO2 electro-catalytic reformation on the cathode were investigated by mass-spectrometer but the electrode surface was analysed by SEM/EDS and XRD methods. [ABSTRACT FROM AUTHOR]

Currently, there is considerable interest in developing cost‐effective, high‐performance electrocatalysts for electrocatalytic carbon dioxide reduction (ECR). Due to their low electrical conductivity and relatively weak catalytic activity, layered bimetallic oxides have rarely been applied in ECR studies. However, they contain a large specific surface area and are rich in Lewis bases, which are favorable for CO2 adsorption. Herein, F and N co‐doped layered bimetallic oxide and reduced graphene oxide composites with precisely controlled morphology are deposited directly on carbon paper using a simple constant current electrodeposition method (FN‐NA‐CLDH@RGO‐X, X denotes the deposition time). Notably, the doping of F helps to suppress the hydrogen precipitation reaction, while the doping of N enhances the adsorption and conversion of CO2. The CO2 reduction study in an H‐type electrolytic cell shows that the FN‐NA‐CLDH@RGO‐100 s electrode‐reduced CO2 to CO at an applied potential of −1.1 V with an efficiency of 87.9% (compared to the reversible hydrogen electrode). In addition, the doping of F favors the reduction of overpotential and the improvement of catalytic activity, while the synergistic effect of F and N enhances the catalytic activity without significant decay in more than 6 h of continuous testing. [ABSTRACT FROM AUTHOR]

Seeking and developing efficient CO2 reduction reaction (CO2RR) electrocatalysts is a hot topic in this era of global warming. Among material candidates for sustainable and cost-effective applications, metal sulfides have attracted attention as promising nature-inspired materials due to multiple adsorption sites which are enhanced by the covalent character of sulfur. This article summarizes the current status regarding the utilization and development of metal sulfide materials as CO2RR electrocatalysts. First, the research background and basic principles of electrochemical CO2RR are introduced. Next, an overview of the main obstacles to developing efficient CO2RR electrocatalysts is presented. The section is followed by a summary of the empirical evidence supporting the application of metal sulfides as CO2RR electrocatalysts beside nature-inspired motivation. The summary of synthesis methods of various metal sulfides is also presented. Furthermore, the paper also highlights the recent works on metal sulfide as efficient CO2RR including the undertaking strategy on the activity enhancement, and finally, discusses the challenges and prospect of metal sulfides-based CO2RR electrocatalysts. Despite recent efforts, metal sulfides remain relatively unexplored as materials for CO2RR electrocatalytic applications. Therefore, this review aims to stimulate novel ideas and research for improved catalyst designs and functionality. [ABSTRACT FROM AUTHOR]

Continuous accumulation and emission into the atmosphere of anthropogenic carbon dioxide (CO2), a major greenhouse gas, has been recognized as a primary contributor to climate change associated with the global warming and acidification of oceans. This has led to drastic changes in the natural ecosystem, and hence an unhealthy ecological environment for human society. Thus, the effective mitigation of the ever increasing CO2 emission has been recognized as the most important global challenge. To achieve zero carbon footprint, novel materials and approaches are required for potentially reducing the CO2 release, while our current fossil-fuel-based energy must be replaced by renewable energy free from emissions. In this paper, porous carbons with hierarchical pore structures are promising for CO2 adsorption and electrochemical CO2 reduction owing to their high specific surface area, excellent catalytic performance, low cost and long-term stability. Since efficient gas-phased (electro) catalysis involves the access of reactants to active sites at the gas-liquid-solid triple phase, the hierarchical porous carbon materials possess multiple advantages for various CO2-related applications with enhanced volumetric and gravimetric activities (e.g., CO2 uptake and current density) for practical operations. Recent studies have demonstrated that porous carbon materials exhibited notable activities as CO2 adsorbents and provided facile conducting pathways and mass diffusion channels for efficient electrochemical CO2 reduction even under the high current operation conditions. Herein, we summarize recent advances in porous carbon materials for CO2 capture, storage, and electrochemical conversion. Prospectives and challenges on the rational design of porous carbon materials for scalable and practical CO2 capture and conversion are also discussed.v [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 (CO2ER) into the renewable and sustainable green fuels, such as low-carbon alcohols, is one of several workable strategies. CO2ER can be combined with renewable electricity to transform intermittent energy sources (such as wind, hydro, and solar) into a fuel that can be stored until it is ready to be used. The intrinsic characteristics of the employed catalyst have a significant and substantial effect on the effi- ciency of CO2ER and the ensuing economic viability. The paradigmatic multicarbon alcohol catalysts should increase the concentration of *CO in the reaction environment, stabilize the key intermediate products during the reaction, and facilitate the C--C coupling interaction. Since graphene has a large surface area and exceptional conductivity, it has been used as a support for active phases (nanoparticles or nanosheets). It is possible for graphene to enhance charge transport and accelerate CO2 conversion through its electronic and structural coupling effects. At the interface, a synergy can be produced that improves CO22ER by increasing *CO adsorption, intermediate binding, and stability. This article focuses on recent advancements in graphene-based catalysts that promote CO2ER to alcohols. Likewise, this paper also describes and discusses the key role graphene plays in catalyzing CO2ER into alcohols. Finally, we hope to provide future ideas for the design of graphene-based electrocatalysts. [ABSTRACT FROM AUTHOR]

The electrocatalytic carbon dioxide reduction reaction (CO2RR) is considered as a promising approach for simultaneous CO2 treatment and production of value-added chemicals. Bismuth has been demonstrated as a fascinating electrocatalyst for selective conversion of CO2 to HCOOH. In this study, we comprehensively investigated the effects of size, morphology, and carbon supports on the CO2RR performance of Bi catalysts to enhance their electrocatalytic CO2RR activity and HCOOH selectivity. Specifically, Bi nanospheres with varying sizes were synthesized by adjusting the amount of polyvinylpyrrolidone (PVP), achieving similar selectivity for HCOOH but increasing current density with decreasing size. Bi nanoplates and Bi nanoflowers were also prepared through the reduction of BiOCl precursors, with Bi nanoflowers demonstrating a superior morphology compared to other Bi nanocrystals while achieving a HCOOH faradaic efficiency (FEHCOOH) of 95% at −1.6 V vs. SCE and excellent durability over 12 hours. The predominance of *HCOO intermediates in the in situ ATR-SEIRA spectra indicates that during the CO2RR, Bi nanoflowers primarily followed the pathway leading to HCOOH production. Furthermore, incorporation of Ketjenblack into the synthesis process resulted in carbon-supported Bi catalysts, which exhibited approximately 20% enhancement in FEHCOOH within a wide potential range from −1.3 V to −1.8 V vs. SCE due to an improved separation effect and electron transfer capacity provided by carbon materials. [ABSTRACT FROM AUTHOR]

Summary: The production of CO via electrochemical CO2 reduction has been recognised as a promising technology that overcomes the environmental issues caused by global warming. It also facilitates the conversion of CO2 into energy sources. Earth‐abundant Zn is a well‐known alternative to noble metal catalysts such as Au and Ag for the electrochemical CO2 reduction to CO. In particular, Zn‐based materials in the form of nanowires are potentially applicable as electrocatalysts in the electrochemical CO2 reduction. However, the conventional methods for manufacturing the nanowire structure are difficult as they require harsh conditions such as high temperatures and excess energy. In this study, Zn‐based nanowire catalysts are prepared by the facile electrodeposition of Zn nanostructures on a substrate followed by their energy‐free solution‐phase reconstitution. Further, their electrochemical performance in the CO2 reduction is investigated in a CO2‐purged 0.5 M KHCO3 electrolyte. By optimising the deposition conditions, hexagonal Zn (h‐Zn) plates with dominant Zn(101) facets, the favoured crystal structure for CO2 reduction, are fabricated on carbon paper. Furthermore, it is found that, during the solution‐phase reconstruction over 16 hours, the h‐Zn plate transforms to a nanowire owing to the differences between the oxidation rates of different crystal facets and the formation of a hydroxide complex. The activity of the reconstructed Zn‐based nanowire catalyst is enhanced further by forming an oxide layer via thermal treatment in a H2 atmosphere. This treatment boosted the reaction kinetics, thereby enhancing the catalyst performance in the CO2 reduction. [ABSTRACT FROM AUTHOR]

In‐depth understanding of the catalytic active sites is of paramount importance for the design of efficient electrocatalysts for CO2 conversion. Here we highlight the structural evolution of SnO2 nanosheets for electrocatalytic CO2 reduction. The transformation of SnO2 into metallic Sn would occur on the surface of catalyst during the catalytic process, followed by enhanced selectivity and activity for the conversion of CO2 to HCOOH. Electrocatalytic characterization and structural analysis demonstrate that the metallic Sn derived from structural evolution plays a dominant role in the CO2 reduction to HCOOH. This work deepens the understanding of the catalytic mechanism and provides a new pathway for the rational design of advanced electrocatalysts for CO2 reduction. [ABSTRACT FROM AUTHOR]

Utilizing renewable electricity for the electrocatalytic conversion of CO2 into alcohols represents a promising avenue for generating value‐added fuels and achieving carbon neutrality. Recently, there has been growing scientific interest in achieving high‐efficiency conversion of CO2 to alcohols, with significant advancements made in mechanism understanding, reactor design, catalyst development, and more. Herein, a thorough examination of the latest advances in electrocatalytic CO2 reduction reaction (CO2RR) to alcohols is provided. General mechanisms and pathways of electrocatalytic conversion of CO2‐to‐alcohols are systematically illustrated. Subsequently, electrolyzer configurations, electrolytes, and electrocatalysts employed in CO2RR are summarized. After that, critical operating parameters (e.g., reaction pressure, temperature, and pH) that would significantly influence the CO2RR process are also analyzed. Finally, the review addresses challenges and offers perspectives in this field to guide future studies aimed at advancing CO2‐to‐alcohols conversion technologies. [ABSTRACT FROM AUTHOR]

The development of efficient carbon dioxide reduction reaction (CO2RR) catalysts is one of the practical solutions to the current environmental problems. Usually, metal-doped catalysts are used for the CO2RR, but the metal elements can easily aggregate, resulting in a reduction in the catalytic performance. In this study, NiFe-LDH was exfoliated to single layer by a solid-phase exfoliation strategy, wherein Ni and Fe were doped on the char material owing to the pyrolysis of the solid-phase exfoliation agent, and the NiFe-CN catalyst with a gauzy and porous structure was obtained. The catalyst possessed excellent catalytic performance; particularly, when the mass fraction of NiFe-LDH was 1 wt%, the prepared catalyst (NiFe-CN-1) showed a faradaic efficiency of 93.5% for the reduction of CO2 to CO at −0.8 V (vs. reversible hydrogen electrode (RHE)) with a CO current density of 10.4 mA cm−2, which was due to the sufficient exposure of active sites and efficient proton transfer channels of NiFe-CN. This strategy provides a new idea to easily mass produce CO2RR electrocatalysts in an environmentally benign way. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO 2 over wood-derived metal-free N-doped carbon electrocatalysts provides a new route for converting CO 2 into value-added fuels However, it is a challenge to efficiently design and screen high-performance electrocatalysts. In this paper, we combined the Marcus equation with the theory of thermal-kinetic correlation to successfully predict the optimal N-C doping ratio. Poplar wood -derived 3D N-doped graphitized carbon with optimal N doping content (pyridine-N 1.87 at%, pyrrole-N, 1.52 at%), high specific surface area (471.2 m2 g−1), and abundant nanopores were successfully obtained with the assistance of melamine (N source), which exhibited a high ECR activity of 86.78 % at a low applied potential of −0.71 V (vs. RHE) and long-term stability of at least 10 cycles. This extends the application of the Marcus equation and improves new ideas for the future design of high-performance electrocatalysts. [Display omitted] • "Thermodynamic-kinetic-N/C doping ratio" curve established. • The accuracy of the "thermodynamics-kinetics -N/C doping ratio" curve is verified. • PB-NC4 shows high industrial potential. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 is a promising pathway for converting CO2 into valuable fuels and chemicals. The local environment at the cathode of CO2 electrolyzers plays a key role in determining activity and selectivity, but currently some mechanisms are still under debate. In particular, alkali metal cations have been shown to enhance the selectivity of metal catalysts, but their role remains less explored for molecular catalysts especially in high-current electrolyzers. Here, we investigated the enhancement effects of cations (Na+, K+, Cs+) on Co phthalocyanine (CoPc) in a state-of-the-art reverse-biased bipolar membrane electrolyzer. When added to the anolyte, these cations increased the Faradaic efficiency for CO, except in the case of Na+ in which the effect was transient, but the effects are convoluted with the transport process through the membrane. Alternatively, these cations can also be added directly to the cathode as chloride salts, allowing the use of a pure H2O anolyte feed, leading to sustained improved CO selectivity (61% at 100 mA cm−2 after 24 h). Our results show that cation addition is a simple yet effective strategy for improving the product selectivity of molecular electrocatalysts, opening up new avenues for tuning their local environment for CO2 reduction. This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'. [ABSTRACT FROM AUTHOR]

A homogeneous electrochemical deposition method was used in this study of CdAl nanoparticles onto CP fibers at −1.1, −1.2, −1.3, and −1.4 V vs. RHE to prepare highly active, selective, and stable CdAl-LDHs nanocatalysts. The electrochemically deposited materials exhibited extremely high CO selectivity during CO 2 RR, with the CO FE reaching 99.71% at −1.6 V vs. RHE and a partial current density of 22.13 mA cm−2. The CdAl-LDHs maintained excellent CO FE along with high CO partial current density. Remarkably, the CdAl-LDHs demonstrated outstanding electrochemical performance that exceeded most of the reported CO 2 reduction to CO electrocatalysts, maintaining stable electrocatalytic performance for more than 30 h with the FE remaining stable at about 99% and a current density at 10.05 mA cm−2 with little decay. [Display omitted] • CdAl nanoparticles with high activity, selectivity and stability were directly deposited on CP fibers by electrochemical deposition method. • The materials prepared by electrochemical deposition exhibit extremely high CO selectivity in the CO 2 RR process, with Faraday efficiency up to 99.71 %. • CdAl-LDHs can maintain the electrocatalytic performance for more than 30 h, and in this process, and the Faraday efficiency can be stable at about 99 %. Layered bimetallic hydroxides are at the forefront of current research in electrocatalytic materials. Although there is considerable research on various bimetallic hydroxides, the study of bimetallic hydroxides for electrocatalytic reduction of carbon dioxide is limited. In this paper, cadmium-aluminum layered bimetallic hydroxide nanoparticles (CdAl-LDHs) were prepared using a simple electrochemical deposition method. The prepared CdAl-LDHs was characterized in detail, and its potential application as an electrocatalyst was discussed. CdAl-LDHs prepared using different methods showed different selectivity in the electrocatalytic reduction of CO 2 to CO. The nanomaterial exhibits excellent CO selectivity in a reaction chamber using 2 %-BMIM(PF 6)(1-butyl-3-methylimidazolium hexafluorophosphate)/DMF(N-N dimethyl formamide) as the electrolyte. The CdAl-LDHs prepared by electrochemical deposition exhibited a maximum CO partial current density of 22.13 mA cm−2 with a remarkable CO Faraday efficiency (FE) of 99.71 %, which is comparable to or even higher than that of noble metal catalysts. This high selectivity for CO indicates its potential as an alternative to expensive noble metal catalysts. Moreover, the catalyst demonstrated high stability over 30 h of continuous operation with stable FE of around 99 % and a current density of around 10.5 mA cm−2, with minimal degradation during the entire reaction cycle. In addition, the catalyst showed a low HER current density of less than 0.1 mA cm−2 at all tested potentials, indicating that the catalyst maintains a high level of CO 2 conversion over the entire range of tested potentials. This suggests its great potential for industrial applications. [ABSTRACT FROM AUTHOR]

Heterogeneous molecular catalysts have attracted considerable attention as carbon dioxide reduction reaction (CO2RR) electrocatalysts. The π‐electron system of conjugated ligands in molecular catalysts may play an important role in determining the activity. In this work, by enlarging π‐conjugation through appending more aromatic substituents on the porphyrin ligand, altered π‐electron system endows the as‐prepared 5,10,15,20‐tetrakis(4‐(pyren‐1‐yl)phenyl)porphyrin CoII with high Faradaic efficiency (ca. 95 %) for CO production, as well as high turnover frequency (2.1 s−1 at −0.6 V vs. RHE). Density functional theory calculation further suggests that the improved electrocatalytic performance mainly originates from the higher proportion of Co dz2 orbital and the CO2 π* orbital in the HOMO of the (Co−porphyrin−CO2)− intermediate with larger π‐conjugation, which facilitates the CO2 activation. This work provides strong evidence that π‐conjugation perturbation is effective in boosting the CO2RR. [ABSTRACT FROM AUTHOR]

In recent decades, significant progress has been achieved in rational developments of electrocatalysts through constructing novel atomistic structures and modulating catalytic surface topography, realizing substantial enhancement in electrocatalytic activities. Numerous advanced catalysts were developed for electrochemical energy conversion, exhibiting low overpotential, high intrinsic activity, and selectivity. Yet, maintaining the high catalytic performance under working conditions with high polarization and vigorous microkinetics that induce intensive degradation of surface nanostructures presents a significant challenge for commercial applications. Recently, advanced operando and computational techniques have provided comprehensive mechanistic insights into the degradation of surficial functional structures. Additionally, various innovative strategies have been devised and proven effective in sustaining electrocatalytic activity under harsh operating conditions. This review aims to discuss the most recent understanding of the degradation microkinetics of catalysts across an entire range of anodic to cathodic polarizations, encompassing processes such as oxygen evolution and reduction, hydrogen reduction, and carbon dioxide reduction. Subsequently, innovative strategies adopted to stabilize the materials' structure and activity are highlighted with an in-depth discussion of the underlying rationale. Finally, we present conclusions and perspectives regarding future research and development. By identifying the research gaps, this review aims to inspire further exploration of surface degradation mechanisms and rational design of durable electrocatalysts, ultimately contributing to the large-scale utilization of electroconversion technologies. [ABSTRACT FROM AUTHOR]

If you take an institutional subscription to any Royal Society of Chemistry journal you are entitled to free, site-wide web access to that journal. The publication of advertisements does not constitute any endorsement by the Royal Society of Chemistry or Authors of any products advertised. TUTORIAL REVIEWS 2224 Targeting RNA with small molecules: from fundamental principles towards the clinic James P. Falese, Anita Donlic and Amanda E. Hargrove* 2244 Contemporary methods for generation of aryl radicals Nikita Kvasovs and Vladimir Gevorgyan* Chem Soc Rev Chemical Society Reviews rsc.li/chem-soc-rev The Royal Society of Chemistry is the world's leading chemistry community. [Extracted from the article]

The design of highly stable, effective, and selective electrocatalysts is essential for electrochemical reduction of carbon dioxide (CO2). Here, on the basis of density functional theory (DFT) computations, the reaction mechanisms of the reduction of CO2 over a series of bis(iminothiolato)metal (TMIT, TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, and Pd) were studied. It is found that the CO2RR activity of TMIT depends on the choice of the central metal atom. Our results demonstrated that HCOOH is the main product for TMIT (TM = Mn, Fe, Co, Ni, Cu, Pd). Among them, MnIT and FeIT are promising CO2RR catalysts for the HCOOH production due to the good selectivity and catalytic activity with the low overpotential of 0.34 V and 0.35 V, respectively. For RuIT and RhIT, the main product is CO, and the strong adsorption of CO on the catalyst surfaces would poison the catalysts. This makes RhIT and RuIT not good CO2RR catalysts. We anticipate that this work may shed new light on the development of high-performance metal organic framework (MOF)-based electrocatalysts. [ABSTRACT FROM AUTHOR]

As an important strategic resource, rare earths (REs) constitute 17 elements in the periodic table, namely 15 lanthanides (Ln) (La–Lu, atomic numbers from 57 to 71), scandium (Sc, atomic number 21) and yttrium (Y, atomic number 39). In the field of catalysis, the localization and incomplete filling of 4f electrons endow REs with unique physical and chemical properties, including rich electronic energy level structures, variable coordination numbers, etc., making them have great potential in electrocatalysis. Among various RE catalytic materials, rare earth oxide (REO)-based electrocatalysts exhibit excellent performances in electrocatalytic reactions due to their simple preparation process and strong structural variability. At the same time, the electronic orbital structure of REs exhibits excellent electron transfer ability, which can reduce the band gap and energy barrier values of rate-determining steps, further accelerating the electron transfer in the electrocatalytic reaction process; however, there is a lack of systematic review of recent advances in REO-based electrocatalysis. This review systematically summarizes the synthesis, properties and applications of REO-based nanocatalysts and discusses their applications in electrocatalysis in detail. It includes the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO2RR), methanol oxidation reaction (MOR), nitrogen reduction reaction (NRR) and other electrocatalytic reactions and further discusses the catalytic mechanism of REs in the above reactions. This review provides a timely and comprehensive summary of the current progress in the application of RE-based nanomaterials in electrocatalytic reactions and provides reasonable prospects for future electrocatalytic applications of REO-based materials. [ABSTRACT FROM AUTHOR]

An efficient carbon dioxide reduction reaction (CO2RR), which reduces CO2 to low-carbon fuels and high-value chemicals, is a promising approach for realizing the goal of carbon neutrality, for which effective but low-cost catalysts are critically important. Recently, many inorganic perovskite-based materials with tunable chemical compositions have been applied in the electrochemical CO2RR, which exhibited advanced catalytic performance. Therefore, a timely review of this progress, which has not been reported to date, is imperative. Herein, the physicochemical characteristics, fabrication methods and applications of inorganic perovskites and their derivatives in electrochemical CO2RR are systematically reviewed, with emphasis on the structural evolution and product selectivity of these electrocatalysts. What is more, the current challenges and future directions of perovskite-based materials regarding efficient CO2RR are proposed, to shed light on the further development of this prospective research area. [ABSTRACT FROM AUTHOR]

The electrochemical carbon dioxide reduction reaction (CO2RR) is an attractive approach for mitigating CO2 emissions and generating value-added products. Consequently, discovery of promising CO2RR catalysts has become a crucial task, and machine learning (ML) has been utilized to accelerate catalyst discovery. However, current ML approaches are limited to exploring narrow chemical spaces and provide only fragmentary catalytic activity, even though CO2RR produces various chemicals. Here, by merging pre-developed ML model and a CO2RR selectivity map, we establish high-throughput virtual screening strategy to suggest active and selective catalysts for CO2RR without being limited to a database. Further, this strategy can provide guidance on stoichiometry and morphology of the catalyst to researchers. We predict the activity and selectivity of 465 metallic catalysts toward four expected reaction products. During this process, we discover previously unreported and promising behavior of Cu-Ga and Cu-Pd alloys. These findings are then validated through experimental methods. Conventional ab initio calculations and machine learning provide limited information on catalytic activity and selectivity and often show discrepancy with experimental results. Here, the authors report a high-throughput virtual screening strategy to identify active and selective catalysts, leading to the discovery of Cu-Ga and Cu-Pd catalysts for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction reaction (CRR) is a promising way to convert carbon dioxide (CO2) into value‐added hydrocarbons to alleviate the ever‐increasing environmental problem and accelerate the realization of carbon cycling. Cost‐effective and stable electrocatalytic materials with low overpotential, superior selectivity, excellent activity and great stability are critically important to achieve such a target. Cu‐based electrocatalysts are promising candidates for electrochemical CRR due to their versatile abilities of converting CO2 into various products. This review analyzes and summarizes the current progress in utilization of Cu‐based catalytic materials for electrochemical CRR. Monometallic, bimetallic, trimetallic, and multimetallic Cu‐based electrocatalysts with variable elemental compositions and tunable morphologies, including Cu nanowires, Cu nanocubes (NCs), Cu porous structures, Cu‐based alloys, Cu‐oxide/hydrogen oxide, Cu single atoms, and 2D substrate‐supported Cu electrocatalysts for CRR, are surveyed. Substantial advances in overcoming the existing bottlenecks of eletrocatalysts and effectively improving CRR performance of Cu‐based electrocatalysts for future applications are systematically discussed. Challenges and perspectives of Cu‐based electrocatalytic materials for CRR are also offered, which may shed light on further development of Cu‐based electrocatalysts with superior performance. It is anticipated that this review will provide a valuable insight into the rational design and synthesis of highly efficient Cu‐based electrocatalysts for large‐scale CRR utilization. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide (CO2) conversion technologies have become new favorites for addressing environmental and energy issues, especially with direct electrocatalytic reduction of CO2 (ECO2RR) and alkali metal‐CO2 (M–CO2) batteries as representatives. They are poised to create new economic drivers while also paving the way for a cleaner and more sustainable future for humanity. Although still far from practical application, ECO2RR has been intensively investigated over the last few years, with some achievements. In stark contrast, M–CO2 batteries, especially aqueous and hybrid M–CO2 batteries, offer the potential to combine energy storage and ECO2RR into an integrated system, but their research is still in the early stages. This article gives an insightful review, comparison, and analysis of recent advances in ECO2RR and M–CO2 batteries, illustrating their similarities and differences, aiming to advance their development and innovation. Considering the crucial role of well‐designed functional materials in facilitating ECO2RR and M–CO2 batteries, special attention is paid to the development of rational design strategies for functional materials and components, such as electrodes/catalysts, electrolytes, and membranes/separators, at the industrial level and their impact on CO2 conversion. Moreover, future perspectives and research suggestions for ECO2RR and M–CO2 batteries are presented to facilitate practical applications. [ABSTRACT FROM AUTHOR]

The large concentration of carbon dioxide (CO2) in the atmosphere can be utilized in industrial production using effective electrocatalysts such as metal‐organic frameworks (MOFs). Due to good properties such as high surface area, designable functionality, and uniform constitution, MOFs are regarded as promising electrocatalysts for the carbon dioxide electrochemical reduction reaction (eCO2RR). This review covers the importance, challenges, and mechanism of eCO2RR, and simply discusses the progress in the synthesis methods and characterization of MOFs. The review also thoroughly discusses the advances of single metal‐based MOFs, mixed metal‐based MOFs, and MOF derivatives as electrocatalysts for efficient eCO2RR. [ABSTRACT FROM AUTHOR]

Tandem catalysis presents a promising strategy to improve the selectivity toward multicarbon products in the electrocatalytic carbon dioxide reduction reaction (CO2RR). For CO2RR, CO is a critical intermediate for producing multicarbon products. However, the management of CO localization and CO diffusion remains underexplored despite its critical role. Herein, a 3D tandem catalyst electrode with silver nanoparticles (Ag NPs) is designed to generate CO as an intermediate product within a copper (Cu) nanoneedle array. Via this nanostructured design, CO2 forms C2+ products with a high Faradaic efficiency (FEC2+) of 64% in an H‐cell and 70% in a flow cell with a current density of 350 mA cm−2. These figures‐of‐merit are currently among the top literature reports. More importantly, in situ Raman spectroscopy and finite‐element method calculations are employed to elucidate the origins of enhanced selectivity. These approaches reveal the crucial role of prolonging the CO diffusion path length for improving CO utilization during CO2 conversion with tandem catalyst systems. The favorable CO2RR FEC2+ in two distinct environments (H‐cell and flow cell) further corroborates that this effect is not limited to a particular reactor environment. Overall, this study provides new insights for designing tandem catalysts for improved CO2RR selectivity to C2+ products. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction to valued products is a promising way to mitigate the greenhouse effect, as this reaction makes use of the excess CO2 in the atmosphere and at the same time forms valued fuels to partially fulfill the energy demand for human beings. Among these valued products, methane is considered a high-value product with a high energy density. This review systematically summarizes the recently studied reaction mechanisms for CO2 electroreduction to CH4. It guides us in designing effective electrocatalysts with an improved electrocatalytic performance. In addition, we briefly summarize the recent progress on CO2 electroreduction into CH4 from the instructive catalyst design, including catalyst structure engineering and catalyst component engineering, and then briefly discuss the electrolyte effect. Furthermore, we also provide a simplified techno-economic analysis of this technology. These summaries are helpful for beginners to rapidly master the contents related to the electroreduction of carbon dioxide to methane and also help to promote the further development of this field. [ABSTRACT FROM AUTHOR]

Catalysis plays a crucial role in all the major applications and challenges in the environment, including energy generation and environmental remediation. Although photocatalysts and electrocatalysts are useful in addressing energy and environmental issues, they have some major drawbacks, such as low efficiency and easy charge recombination which limits their applications. Hence, it is imperative to design and explore new catalytic techniques that include non‐photoresponsive catalysts. In this review, the detailed possibilities, characteristics and prospects of non‐photoresponsive catalysts, such as piezocatalysts, thermocatalysts, pyrocatalysts, and tribocatalysts along with hybrid catalysts are described. The overall mechanism of each catalytic technique and its applications in different fields such as energy generation, environmental remediation, and carbon dioxide reduction are discussed. [ABSTRACT FROM AUTHOR]

High‐entropy alloys refer to near‐equimolar alloys of five or more elements and are receiving attention due to their unique physical and chemical properties. In electrocatalysis, they serve as active sites in multiple elements, favoring the optimized adsorption/desorption property toward the target reaction. High‐entropy nanomaterials (HENMs) are attractive candidates as electrocatalysts by taking advantage of a high surface‐to‐volume ratio and tailored composition. This review begins with the concept of high‐entropy materials and various strategies for designing electrocatalysts. Then, the recent advances in HENMs as electrocatalysts for various applications (water‐splitting reaction, carbon dioxide reduction reaction, alcohol oxidation reaction, etc.) are introduced with their catalytic performances. Finally, based on the current status of HENMs for electrocatalysis, the challenging aspects and the future insight of HENMs for advanced electrocatalysis are discussed and proposed. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide reduction reaction (CO2RR) provides an attractive approach to carbon capture and utilization for the production high-value-added products. However, CO2RR still suffers from poor selectivity and low current density due to its sluggish kinetics and multitudinous reaction pathways. Single-atom catalysts (SACs) demonstrate outstanding activity, excellent selectivity, and remarkable atom utilization efficiency, which give impetus to the search for electrocatalytic processes aiming at high selectivity. There appears significant activity in the development of efficient SACs for CO2RR, while the density of the atomic sites remains a considerable barrier to be overcome. To construct high-metal-loading SACs, aggregation must be prevented, and thus novel strategies are required. The key to creating high-density atomically dispersed sites is designing enough anchoring sites, normally defects, to stabilize the highly mobile separated metal atoms. In this review, we summarized the advances in developing high-loading SACs through defect engineering, with a focus on the synthesis strategies to achieve high atomic site loading. Finally, the future opportunities and challenges for CO2RR in the area of high-loading single-atom electrocatalysts are also discussed. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction reaction (CO2RR), driven by clean electric energy such as solar and wind, can not only alleviate environmental greenhouse effect stemming from excessive CO2 emissions, but also realize the storage of renewable energy, for it guarantees the production of value-added chemicals and fuels. Among CO2RR products, formic acid shows great advantages in low energy consumption and high added-value, and thus producing formic acid is generally considered as a profitable line for CO2RR. Bismuth-based electrocatalysts exhibit high formic acid selectivity in CO2RR. Herein, we review the recent progress in bismuth-based electrocatalysts for CO2RR, including material synthesis, performance optimization/validation, and electrolyzers. The effects of morphologies, structure, and composition of bismuth-based electrocatalysts on CO2RR performance are highlighted. Simultaneously, in situ spectroscopic characterization and DFT calculations for reaction mechanism of CO2RR on Bi-based catalysts are emphasized. The applications and optimization of electrolyzers with high current density for CO2RR are summarized. Finally, conclusions and future directions in this field are prospected. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of carbon dioxide (CO 2 ) to formate is energetically inefficient because high overpotential is required for reduction of CO 2 to formate on most traditional catalysts. In this paper, a novel nano-sized Bi-based electrocatalyst deposited on a Cu foil has been synthesized, which can be used as a cathode for electrochemical reduction of CO 2 to formate with a low overpotential (0.69 V) and a high selectivity (91.3%). The electrocatalyst can show excellent catalytic performance toward reduction of CO 2 which can probably be attributed to the nano-sized structure and the surface oxide layer. The energy efficiency for reduction of CO 2 to formate can reach to 50% when an Ir x Sn y Ru z O 2 /Ti electrode is used as anode, it is one of the highest values found in the literatures and very practicable for sustainable fuel synthesis. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide reduction reaction (CO2RR) using clean electric energy provides a sustainable route to generate highly‐valuable chemicals and fuels, which is beneficial for realizing the carbon‐neutral cycle. Up to now, achieving a narrow product distribution and highly targeted product selectivity over Cu‐based electrocatalysts is still a big challenge. Herein, sulfur modification on different crystal planes of cuprous oxide (Cu2O) is demonstrated, results in an improvement for formate generation to different degrees. Experimental results and density functional theory (DFT) calculations reveal that sulfur species modified on the surface of Cu2O (100) facet effectively lower the formation energy of key intermediate *OCOH for formate generation compared with Cu2O (111) facet. As a consequence, the modification of p‐Block elements over Cu‐based electrocatalysts is an effective strategy to optimize the adsorption energy of key intermediate during CO2RR, leading to a highly selective product. [ABSTRACT FROM AUTHOR]

The electrocatalytic carbon dioxide reduction reaction is an effective means of combating the greenhouse effect caused by massive carbon dioxide emissions. Carbon nitride in the graphitic phase (g-C3N4) has excellent chemical stability and unique structural properties that allow it to be widely used in energy and materials fields. However, due to its relatively low electrical conductivity, to date, little effort has been made to summarize the application of g-C3N4 in the electrocatalytic reduction of CO2. This review focuses on the synthesis and functionalization of g-C3N4 and the recent advances of its application as a catalyst and a catalyst support in the electrocatalytic reduction of CO2. The modification of g-C3N4-based catalysts for enhanced CO2 reduction is critically reviewed. In addition, opportunities for future research on g-C3N4-based catalysts for electrocatalytic CO2 reduction are discussed. [ABSTRACT FROM AUTHOR]

Electrocatalytic carbon dioxide reduction reaction (CO2RR) is a promising method to solve current environment and energy issues. Copper-based catalysts have been widely studied for converting CO2 into value-added hydrocarbon products. Cu monometallic catalyst has been proved to have some shortcomings, including relatively high energy barriers and diverse reaction pathways, leading to low reaction activities and poor product selectivity, respectively. Recently copper-based bimetallic tandem catalysts have attracted extensive attentions due to their special catalyst structure, which can be easily regulated to achieve high CO2RR reactivity and product selectivity. With the development of quantum chemistry calculations and spectroscopic characterization methods, deep understandings of CO2RR from the mechanism perspective provide a broad horizon for the design of effi- cient catalysts. This review offers a good summary of reaction mechanisms and product regulation strategies over copper-based bimetallic catalysts, along with a brief discussion on future directions towards their practical applications. [ABSTRACT FROM AUTHOR]

Continuous accumulation and emission into the atmosphere of anthropogenic carbon dioxide (CO2), a major greenhouse gas, has been recognized as a primary contributor to climate change associated with the global warming and acidification of oceans. This has led to drastic changes in the natural ecosystem, and hence an unhealthy ecological environment for human society. Thus, the effective mitigation of the ever increasing CO2 emission has been recognized as the most important global challenge. To achieve zero carbon footprint, novel materials and approaches are required for potentially reducing the CO2 release, while our current fossil-fuel-based energy must be replaced by renewable energy free from emissions. In this paper, porous carbons with hierarchical pore structures are promising for CO2 adsorption and electrochemical CO2 reduction owing to their high specific surface area, excellent catalytic performance, low cost and long-term stability. Since efficient gas-phased (electro)catalysis involves the access of reactants to active sites at the gas-liquid-solid triple phase, the hierarchical porous carbon materials possess multiple advantages for various CO2-related applications with enhanced volumetric and gravimetric activities (e.g., CO2 uptake and current density) for practical operations. Recent studies have demonstrated that porous carbon materials exhibited notable activities as CO2 adsorbents and provided facile conducting pathways and mass diffusion channels for efficient electrochemical CO2 reduction even under the high current operation conditions. Herein, we summarize recent advances in porous carbon materials for CO2 capture, storage, and electrochemical conversion. Prospectives and challenges on the rational design of porous carbon materials for scalable and practical CO2 capture and conversion are also discussed.

Single-atom catalysts (SACs) have emerged as well-known catalysts in renewable energy storage and conversion systems. Several supports have been developed for stabilizing single-atom catalytic sites, e.g., organic-, metal-, and carbonaceous matrices. Noticeably, the metal species and their local atomic coordination environments have a strong influence on the electrocatalytic capabilities of metal atom active centers. In particular, asymmetric atom electrocatalysts exhibit unique properties and an unexpected carbon dioxide reduction reaction (CO2RR) performance different from those of traditional metal-N4 sites. This review summarizes the recent development of asymmetric atom sites for the CO2RR with emphasis on the coordination structure regulation strategies and their effects on CO2RR performance. Ultimately, several scientific possibilities are proffered with the aim of further expanding and deepening the advancement of asymmetric atom electrocatalysts for the CO2RR. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate the catalytic performance of carbon‐doped selenium (C‐Se), prepared by a facile reproducible hydrothermal method, toward electro‐reduction of CO2 (ERC). Here, we adopted two binders, namely Fumion® (anion exchange) and Nafion® (cation exchange) to investigate the catalytic performance and product selectivity in alkaline electrolyte, KHCO3. The C‐Se/Fumion catalysts exhibit superior activity and stability toward ERC compared with C‐Se/Nafion. The main products obtained at a potential range (‐0.9 to ‐1.2 V vs. RHE) of ERC are CH4 and C2H6 for C‐Se/Nafion and CH4 for C‐Se/Fumion. The maximum faradic efficiency of the C‐Se/Nafion for CH4 and C2H6 production are 16.7% and 8.9% and that of the C‐Se/Fumion for CH4 production is 25.5% at ‐1.1 V vs. RHE. The present study reveals the influence of ionic binders on the selectivity of the ERC products. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of CO2 to other high value-added chemicals under ambient conditions is a promising and ecofriendly strategy to achieve sustainable carbon recycling. However, the CO2 reduction reaction (CO2RR) is still confronted with a large number of challenges, such as high reaction overpotential and low product selectivity. Therefore, the rapid development of appropriate electrocatalysts is the key to promoting CO2 electroreduction. Over the past few decades, Au-based nanocatalysts have been demonstrated to be promising for the selective CO2RR to CO owing to their low reaction overpotential, good product selectivity, high Faraday efficiency and inhibition of the hydrogen evolution reaction. In this respect, this review first introduces the fundamentals of the electrochemical reduction of CO2 and then focuses on recent accomplishments with respect to Au-based nanocatalysts for CO2RR. The manipulation of various factors, e.g., the nanoporous structure, nanoparticle size, composition, morphology, support and ligand, allows for the identification of several clues for excellent Au-based nanocatalysts. We hope that this review will offer readers some important insights on Au-based catalyst design and provide new ideas for developing robust electrocatalysts. [ABSTRACT FROM AUTHOR]

In this paper, Ti/ZnO–Fe 2 O 3 composite derived from Ti/Schiff base intercalated ZnFe layered double hydroxides was used as thin film electrode in CO 2 photoelectroreduction. The influence of molar ratio of Ti/Fe and calcination temperature, which would affect the composites' physicochemical property and the photoelectrocatalytic performance for CO 2 reduction, were investigated in detail. The characterization results from XRD, SEM, TEM, UV-vis and BET showed that Ti/ZnO–Fe 2 O 3 composite with flower–like crystal from had small particle sizes, narrow band gap and excellent textural properties. The final product of CO 2 photoelectroreduction was methanol and the intermediates were formic acid and formaldehyde. The methanol field reached at 0.773 mmol/cm 2 after 3 h reaction with 0.5 V voltage by Ti/ZnO–Fe 2 O 3 composite with Ti/Fe = 1, calcined at 800 °C. In addition, the CO 2 photoelectroreduction pathway and the reason for highly efficient photoelectrocatalytic activity of the composite were also discussed. [ABSTRACT FROM AUTHOR]

Ethylene is particularly attractive due to its major importance as a feedstock for various applications including the polymer industry. As such, catalyst and electrolyzer developments are crucial to achieve industrially relevant ethylene production and efficiency levels. Here, a tandem electrocatalyst composed of copper nanocubes and nickel‐coordinated nitrogen‐doped carbon (NiNC) is presented, which is integrated into gas diffusion electrodes (GDEs) for direct conversion of vapor‐fed CO2 into ethylene. Evaluation of tandem GDEs in the vapor‐fed flow electrolyzer shows significantly increased ethylene selectivity in terms of faradaic efficiency and C2H4/CO ratio compared to a non‐tandem copper GDE. The enhancements are attributed to the increased local CO availability near the copper surface via effective CO2 to CO conversion on neighboring NiNC. The experimental results are validated by 3D resolved continuum simulations, which show increased flux of higher‐order products with the added CO flux from NiNC. The practical viability of Cu/NiNC catalyst is further evaluated in a membrane electrode assembly electrolyzer, achieving 40% FE toward ethylene at 150 mA cm−2 and 3.2 V. These findings highlight the high selectivity and formation rate of ethylene achieved by successful device integration of the Cu/NiNC catalyst, demonstrating the potential for implementation in large‐scale sustainable CO2 electrolyzers. [ABSTRACT FROM AUTHOR]

One of the most important current topics in the renewable and sustainable energy scenario is the CO2 electro‐reduction reaction (CO2RR), which is an alternative and important route for its conversion into various high value‐added chemicals, therefore making up a CO2 recycling process. Despite its importance and the works already developed in this field, many challenges still need to be overcome for CO2RR to reach high values of efficiency and selectivity. This is even more challenging considering that this reaction occurs with the transfer of several electrons, making the investigation and elucidation of the reaction mechanism a real need. Thus, several characterization techniques have been employed, and specially, the on‐line Electrochemical Mass Spectrometry (EC‐MS) technique emerges as a powerful tool, thus making possible to improve the understanding of reaction pathways, through the identification of products and intermediaries, and allowing the screening of electrocatalyst potentials for CO2RR. Herein, we present the evolution of adaptations of general electrochemical cell designs for the study of the CO2RR. [ABSTRACT FROM AUTHOR]

The fundamental relationship between structure and properties, which is called "structure‐property", plays a vital role in the rational designing of high‐performance catalysts for diverse electrocatalytic applications. Low‐dimensional (LD) nanomaterials, including 0D, 1D, 2D materials, combined with low‐nuclearity metal atoms, ranging from single atoms to subnanometer clusters, are currently emerging as rising star nanoarchitectures for heterogeneous catalysis due to their well‐defined active sites and unbeatable metal utilization efficiencies. In this work, a comprehensive experimental and theoretical review is provided on the recent development of single atom and atomic cluster‐decorated LD platforms towards some typical clean energy reactions, such as water‐splitting, nitrogen fixation, and carbon dioxide reduction reactions. The upmost attractive structural properties, advanced characterization techniques, and theoretical principles of these low‐nuclearity electrocatalysts as well as their applications in key electrochemical energy devices are also elegantly discussed. [ABSTRACT FROM AUTHOR]

A series of RuII-polypyridyl complexes of the design [RuII(tpy)(NN)X]n+ (tpy = 2,2':6',2''-terpyridine; NN = bidentate polypyridine; X = Cl- or CH3CN; n = 1 or 2) have been synthesized and analyzed for their ability to function as electrocatalysts in the reduction of CO2 to CO. Varying the electron-donating/withdrawing character of the NN polypyridyl ligand has allowed for modification of electron density at the formally RuII metal center. Complexes where X = Cl- display ligand substitution for CH3CN with differing rates of Cl- dissociation (k-Cl), therefore providing a degree of insight into the electron density and thus the chemical activity at the RuII center. Detailed analysis of the cyclic voltammograms under argon vs. CO2 atmospheres using multiple switching potentials and scan rates ranging from ν = 25-2000 mV s-1 has painted a picture of how monodentate ligand lability due to NN polypyridyl electron-donating character is related to electrocatalytic CO2 reduction activity of RuII-polypyridyl complexes. From these studies, multiple mechanistic pathways towards generating the catalytically active [Ru(tpy-)(NN-)CO2]0 species are proposed and differ via the order of electrochemical and chemical processes. [ABSTRACT FROM AUTHOR]

This paper presents the experimental investigation of copper loaded carbon nanotubes (CNTs) electrocatalysts for the electrochemical reduction of carbon dioxide. The electrocatalysts were synthesized by homogeneous deposition precipitation method (HDP) using urea as precipitating agent. The prepared catalysts were characterized by TEM, SEM, XRD, XPS, BET, and FTIR for their morphology and structure. Characterization results confirm the deposition of Cu nanoparticles (3-60 nm) on CNTs. Linear sweep voltammetry (LSV) and chronoamperometry (CA) were used to investigate the activity of the as-prepared catalysts for the electrochemical reduction of carbon dioxide. The electrocatalysts reduced CO2 with high current density in the potential range 0~-3V versus SCE (standard calomel electrode). Among all catalysts tested, 20 wt. % copper loaded CNTs showed maximum activity. Gas chromatograph with TCD was used to analyze liquid phase composition. The faradaic efficiency for methanol formation was estimated to be 38.5%. [ABSTRACT FROM AUTHOR]

Strain engineering of nanomaterials, namely, designing, tuning, or controlling surface strains of nanomaterials is an effective strategy to achieve outstanding performance in different nanomaterials for their various applications. This article summarizes recent progress and achievements in the development of strain‐rich electrocatalysts (SREs) and their applications in the field of electrochemical energy conversion technologies. It starts from the definition of lattice strains, followed by the classification of lattice strains where the mechanisms of strain formation and the reported methods to regulate related strains are elaborated. The SRE characterization techniques are overviewed, focusing deeply on the clarification of the strain‐property relationship of these SREs. Their applications for different electrocatalytic reactions are further highlighted, including the hydrogen evolution reaction, oxygen reduction reaction, oxygen evolution reaction, alcohol oxidation reaction, electrochemical carbon dioxide reduction reaction, and nitrogen reduction reaction. Related reaction mechanisms of the SREs are interpreted after taking catalytic performance, as well as the relationship between the SRE properties and their strains into account. The challenges and future opportunities to regulate SREs are finally outlined and discussed together with their potential applications in different fields. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction (CO2RR) is a key technology to convert greenhouse gas CO2 to value‐added products, such as CO and formic acid (HCOOH). In the present study, two‐dimensional Cu‐ and Al‐based layered double hydroxides (Cu−Al/LDHs) were applied as CO2RR catalysts. The catalysts were synthesized using a simple co‐precipitation method employing sodium carbonate solutions with different pH and synthesis temperatures. The elemental ratio of Cu and Al, and sheet size were controlled. The most active Cu−Al/LDH showed a faradaic efficiency for CO generation of 42 % and one for formate generation of 22 % at the current density of 50 mA using a gas diffusion electrode system under galvanostatic conditions. Our result indicates that the sheet size of the LDH sheet is a critical parameter for determining CO2RR activity. [ABSTRACT FROM AUTHOR]

The conventional environment polluting energy sources and the continuous growing energy demand compelled researchers to find alternative energy sources. Therefore, in recent years, extensive research has been carried out in synthesizing catalysts for energy conversion applications. This review focuses on the application of various electrodeposition methods in the synthesis of energy‐related electrocatalyst and briefly discusses different electrocatalyst characterization techniques. Further, the influence of various parameters on the electrocatalyst activity and stability is highlighted. Electrocatalyst application in clean energy conversion reactions, such as the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, carbon dioxide reduction reaction, nitrogen reduction reaction along with the metal‐air/CO2 battery, are reviewed. Finally, the comparative experimental data are provided as a reference to synthesize the next‐generation electrodeposited electrocatalyst in clean energy conversions and beyond. [ABSTRACT FROM AUTHOR]

The reduction of carbon dioxide (CO2) into value‐added fuels using an electrochemical method has been regarded as a compelling sustainable energy conversion technology. However, high‐performance electrocatalysts for CO2 reduction reaction (CO2RR) with high formate selectivity and good stability need to be improved. Earth‐abundant Bi has been demonstrated to be active for CO2RR to formate. Herein, we fabricated an extremely active and selective bismuth nanosheet (Bi‐NSs) assembly via an in situ electrochemical transformation of (BiO)2CO3 nanostructures. The as‐prepared material exhibits high activity and selectivity for CO2RR to formate, with nearly 94% faradaic efficiency at −1.03 V (versus reversible hydrogen electrode (vs. RHE)) and stable selectivity (>90%) in a large potential window ranging from −0.83 to −1.18 V (vs. RHE) and excellent durability during 12 h continuous electrolysis. In addition, the Bi‐NSs based CO2RR/methanol oxidation reaction (CO2RR/MOR) electrolytic system for overall CO2 splitting was constructed, evidencing the feasibility of its practical implementation. [ABSTRACT FROM AUTHOR]