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Double-atom catalysts (DACs) for harmful nitrate (NO3−) electroreduction to valuable ammonia (eNO3RR) is attractive for both environmental remediation and energy transformation. However, the limited metal loading in most DACs largely hinders their applications in practical catalytic applications. Therefore, exploring ultrahigh-density (UHD) DACs with abundant active metal centers and excellent eNO3RR activity is highly desired under the site-distance effect. Herein, starting from the experimental M2N6 motif deposited on graphene, we firstly screened the low-density (LD) Mn2N6 and Fe2N6 DACs with high eNO3RR activity and then established an appropriate activity descriptor for the LD–DAC system. By utilizing this descriptor, the corresponding Mn2N6 and Fe2N6 UHD–DACs with dynamic, thermal, thermodynamic, and electrochemical stabilities, are identified to locate at the peak of activity volcano, exhibiting rather-low limiting potentials of −0.25 and −0.38 V, respectively. Further analysis in term of spin state and orbital interaction, confirms that the electronic state effect similar to that of LD–DACs enable the excellent eNO3RR activity to be maintained in the UHD–DACs. These findings highlight the promising application of Mn2N6 and Fe2N6 UHD–DACs in nitrate electroreduction for NH3 production and provide impetus for further experimental exploration of ultrahigh-density DACs based on their intrinsic electronic states. [ABSTRACT FROM AUTHOR]

By functionalizing various polyphenyl nuclei with ester groups, five kinds of polyphenyl benzoate based electrochromic materials (M1–M5) are synthesized and characterized. These materials show typical aggregation-induced emission and aggregation-enhanced emission in water/N-methylpyrrolidone, good electrochemical properties, and an obvious electrochromic phenomenon. In the process of electrochemical reduction, each material shows distinct and well-separated redox couples, the introduction of ester moieties makes electron transfer much easier compared to the polyphenyl nuclei, and the synergistic effect of the ester group and polyphenyl structure reduces the LUMO level of the corresponding polyphenyl benzoates. In contrast, the polyphenyl nuclei markedly affect their electrochromic properties, and the electrochromic devices based on M1–M5 exhibit five different colored states. By combining with density functional theory calculations, it is found that an appropriate amount of benzene rings in the central benzene cores (M2 and M4) can effectively improve the coloration efficiency, response time, and switching stability; fewer benzene rings in the central benzene core (M1) cannot achieve stable conjugation of the material in the reduced state, while an excess of benzene rings in the central benzene core (M5) leads to excessive molecular volume, and this will lead to space congestion and is not beneficial for electron transfer. The application of M1–M5 in multi-colored functional display devices is explored, indicating its potential application prospect in display fields. [ABSTRACT FROM AUTHOR]

Concurrent activation of CO2 and H2O is essential for CO2 electroreduction reaction, but challenging. A sulfur-doped carbon nanotubes-supported nickel phthalocyanine (NiPc/S-CNTs) can concurrently activate CO2 and H2O, promoting CO2 protonation to *COOH. The NiPc/S-CNTs achieves CO Faraday efficiency of >96% at current density from −20 to −140 mA cm−2. [ABSTRACT FROM AUTHOR]

Oxygen (O2) electroreduction offers a green approach for singlet oxygen (1O2) synthesis in wastewater contaminants detoxification. However, traditional single O2 activation on single‐metal catalytic sites seriously suffers from the kinetically‐unfavorable desorption of adsorbed superoxide species (•O2−*/•OOH*). Here, we demonstrate a novel dual O2 coactivation pathway on shortened Fe1−OV−Ti sites for superior 1O2 electrosynthesis through a rapid disproportionate process between surface‐confined •O2−*/•OOH*. Theoretical calculations combined with in situ electrochemical spectroscopies demonstrated that the shortened distance between Fe single atom and adjacent unsaturated Ti atom facilitates the direct recombination of surface‐confined Fe−•OOH and Ti−•OO− to yield 1O2, bypassing the formidable •O2−*/•OOH* desorption process. Impressively, Fe1−OV−Ti could realize an excellent 1O2 electrosynthesis rate of 54.5 μmol L−1 min−1 with an outstanding 1O2 selectivity of 97.6 % under neutral condition, surpassing that of Fe1−O−Ti (27.1 μmol L−1 min−1, 91.7 %). Using tetracycline (TC) as a model pollutant, the resulting Fe1−OV−Ti electrode achieved nearly 100 % degradation in 120 min at −0.6 V, meanwhile preventing the generation of toxic intermediates. This study provides a new 1O2 electrosynthesis strategy by controlling the distance of adjacent catalytic sites for the coactivation of dual molecular oxygen. [ABSTRACT FROM AUTHOR]

Protonic ceramic fuel cells (PCFCs), which are based on proton conducting electrolytes, are a class of power generation devices that can efficiently operate at the intermediate (500–700 °C), even low (450 °C) temperatures, but their development is hindered by sluggish cathodic kinetics at reduced temperatures. At the PCFC cathode, the absorbed oxygen molecules react with oxygen vacancies, protons and electrons to generate water and release electrical energy. Thus, the PCFC cathode materials require percolation network for proton, oxide-ion, and electron carriers simultaneously. In this work, we developed a triple ionic-electronic conductor BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ as a new cathode material for the PCFCs using BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ as the electrolyte. Anode supported cells were fabricated and the performances were investigated. Compared with the parent oxide, tungsten doping can significantly improve the electrochemical reduction kinetic of oxygen. The BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ based PCFC obtained the peak power density of 688 mW ⋅ cm−2 at 600 °C, which is 1.29 time higher than that of BaCo 0.4 Fe 0.4 Zr 0.2 O 3-δ based PCFC (the peak power density of 534 mW ⋅ cm−2 at 600 °C). Moreover, BaCo 0.4 Fe 0.4 Zr 0.15 W 0.05 O 3-δ has a better thermal expansion matching with the electrolyte material BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ. [Display omitted] [ABSTRACT FROM AUTHOR]

The escalating concentration of carbon dioxide in the atmosphere is a pressing environmental concern, necessitating the development of efficient technologies for CO2 reduction and utilization. In this context, metal–organic frameworks (MOFs) emerge as promising catalysts due to their tunable structures and unique chemical properties. This study focuses on the synthesis, characterization, and evaluation of amino-functionalized MOFs with cobalt and nickel nodes for the electrochemical reduction of CO2. Electrochemical investigations reveal that a cobalt-based MOF primarily facilitates the production of methane, demonstrating high selectivity and efficiency under controlled conditions. In contrast, a nickel-based MOF exhibits a broader array of reduction products, including methane, CO, and ethanol, with a significant conversion efficiency. These differences underscore the impact of the central metal node on the catalytic activity and product distribution. This comprehensive study not only advances our understanding of MOF-based catalysts for CO2 reduction but also underscores the significance of molecular engineering in enhancing the selectivity and efficiency of these processes. By demonstrating the potential of amino-functionalized MOFs with specific metal nodes, we contribute to the development of sustainable solutions for carbon capture and utilization, aligning with global efforts to mitigate climate changes and foster a green chemical industry. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Cu‐catalyzed electrochemical CO2 reduction reaction (CO2RR) and CO reduction reaction (CORR) are of great interest due to their potential to produce carbon‐neutral and value‐added multicarbon (C2+) chemicals. In practice, CO2RR and CORR are typically operated at industrially relevant current densities, making the process exothermal. Although the increased operation temperature is known to affect the performance of CO2RR and CORR, the relationship between temperatures and kinetic parameters was not clearly elaborated, particularly in zero‐gap reactors. In this study, we detail the effect of the temperature on Cu‐catalyzed CO2RR and CORR. Our electrochemical and operando spectroscopic studies show that high temperatures increase the activity of CO2RR to CO and CORR to C2H4 by enhancing the mass transfer of CO2 and CO. As the rates of these two processes are highly influenced by reactant diffusion, elevating the operating temperature results in high local CO2 and CO availability to accelerate product formation. Consequently, the *CO coverage in both cases increases at higher temperatures. However, under CO2RR conditions, *CO desorption is more favorable than carbon‐carbon (C—C) coupling thermodynamically at high temperatures, causing the reduction in the Faradaic efficiency (FE) of C2H4. In CORR, the high‐temperature‐augmented CO diffusion overcomes the unfavorable adsorption thermodynamics, increasing the probability of C—C coupling. [ABSTRACT FROM AUTHOR]

[Display omitted] Electrochemical nitrate reduction reaction (NO 3 RR) offers a cost-effective and environmentally friendly method to simultaneously yield valuable NH 3 and alleviate NO 3 − pollution under mild operating conditions. However, this complicated eight-electron reaction suffers from low selectivity and Faradaic efficiency, which highlight the importance of developing efficient catalysts, but still a critical challenge. Here, a theoretical screening is performed on transition metal-tetragonal carbon nitride (TM@T-C 2 N) as active and selective electrocatalysts for NO 3 RR, where detailed reaction mechanisms and activity origins are explored. In addition, five-step screening criteria and volcano plots enable fast prescreening among numerous candidates. We identify that V@T-C 2 N and Cr@T-C 2 N are promising candidates with low overpotentials and high selectivity and stability. In particular, a significant negative correlation between the adsorption strength of nitrate and the Gibbs free energy for the last proton-electron coupling step (*NH 2 →*NH 3) was existed, which is considerably advantaged to track the activity trend and reveal the origin of activity. This work provides theoretical insights into the rational design of TM–N 4 /C catalysts for NO 3 RR and paves a valuable electrochemical screening framework for other multi-step reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atomically dispersed catalyst with single Cu atom and atomic Ni clusters was prepared. • Cu SA Ni AC /NMHCS achieves a high FE CO of over 90% across a wide potential range. • Cu SA Ni AC /NMHCS shows the highest FE CO of 98 % at − 0.9 V vs. RHE. • Cu SA Ni AC /NMHCS exhibits excellent long-term stability for CO 2 RR to produce CO. • Positively shifted ε d of Ni 3 d orbital contributes to the enhanced CO 2 RR performance. The rational design of catalysts with atomic dispersion and a deep understanding of the catalytic mechanism is crucial for achieving high performance in CO 2 reduction reaction (CO 2 RR). Herein, we present an atomically dispersed electrocatalyst with single Cu atom and atomic Ni clusters supported on N-doped mesoporous hollow carbon sphere (Cu SA Ni AC /NMHCS) for highly efficient CO 2 RR. Cu SA Ni AC /NMHCS demonstrates a remarkable CO Faradaic efficiency (FE CO) exceeding 90% across a potential range of −0.6 to −1.2 V vs. reversible hydrogen electrode (RHE) and achieves its peak FE CO of 98% at −0.9 V vs. RHE. Theoretical studies reveal that the electron redistribution and modulated electronic structure—notably the positive shift in d-band center of Ni 3 d orbital—resulting from the combination of single Cu atom and atomic Ni clusters markedly enhance the CO 2 adsorption, facilitate the formation of *COOH intermediate, and thus promote the CO production activity. This study offers fresh perspectives on fabricating atomically dispersed catalysts with superior CO 2 RR performance. [ABSTRACT FROM AUTHOR]

The era of an energy economy driven by “carbon neutrality” is putting forward stricter requirements for the use of carbon resources and the governance of CO2. Electrochemical reduction of carbon dioxide reaction (CO2RR), driven by renewable energy, is a practical energy storage technology with broad application prospects. It can reduce CO2 into carbon‐based fuels and chemical products. Among them, multi‐carbon (C2+) products have higher energy density and larger market size, and can significantly reduce the global demand for fossil fuels and close the artificial carbon cycle. Introducing additional active sites into Cu‐based catalysts to prepare dual‐site tandem catalysts can regulate the electronic and geometric structure of the catalysts, break linear scale relationships, reduce reaction potential barriers, and bring superb and stable catalytic performance. Various types of dual‐site tandem catalysts are developed, and the understanding of the tandem effect is pushed to a higher level. This paper reviews several typical dual‐site tandem catalysts: atom–atom dual‐site tandem catalysts, atom‐particle dual‐site tandem catalysts, particle–particle dual‐site tandem catalysts, and heterogeneous interface dual‐site tandem catalysts. It then deeply analyzes the reaction mechanism and research progress of these advanced catalysts in CO2RR. In addition, the challenges and opportunities faced by such catalysts are also discussed. [ABSTRACT FROM AUTHOR]

The presence of oxygen vacancies (Vo) in electrocatalysts plays a significant role in improving the selectivity and activity of CO2 reduction reaction (CO2RR). In this study, 1D material with large surface area is utilized to enable uniform Vo formation on the catalyst. 1D structured indium selenoiodide (InSeI) is synthesized and used as an electrocatalyst for the conversion of CO2 to formate. The electrochemical treatment of InSeI leads to the leaching of Se and I from the catalyst surface and the formation of Vo. The resulting Vo promotes the activity of the CO2RR, which increases the local pH of the catalyst surface and chemically maintains the oxidized metal sites on the catalyst. Owing to these characteristics, activated In wire exhibited remarkable CO2RR activity, thereby surpassing 93% FEformate at 500 mA cm−2, with a maximum of 97.3% FEformate at 100 mA cm−2. Moreover, the catalytic activity remained consistent for over 50 h at 100 mA cm−2 (FEformate >88%). Thus, the findings imply that using 1D materials can facilitate the formation of oxygen vacancies on the catalyst surface and improve the selectivity and durability of CO2RR. This indicates the potential for further research on 1D materials as electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of CO2 into C2 products of high economic value provides a promising strategy to realize resourceful CO2 utilization. Rational design and construct dual sites to realize the CO protonation and C−C coupling to unravel their structure‐performance correlation is of great significance in catalysing electrochemical CO2 reduction reactions. Herein, Cu−Cu dual sites with different site distance coordinated by halogen at the first‐shell are constructed and shows a higher intramolecular electron redispersion and coordination symmetry configurations. The long‐range Cu−Cu (Cu−I−Cu) dual sites show an enhanced Faraday efficiency of C2 products, up to 74.1 %, and excellent stability. In addition, the linear relationships that the long‐range Cu−Cu dual sites are accelerated to C2H4 generation and short‐range Cu−Cu (Cu−Cl−Cu) dual sites are beneficial for C2H5OH formation are disclosed. In situ electrochemical attenuated total reflection surface enhanced infrared absorption spectroscopy, in situ Raman and theoretical calculations manifest that long‐range Cu−Cu dual sites can weaken reaction energy barriers of CO hydrogenation and C−C coupling, as well as accelerating deoxygenation of *CH2CHO. This study uncovers the exploitation of site‐distance‐dependent electrochemical properties to steer the CO2 reduction pathway, as well as a potential generic tactic to target C2 synthesis by constructing the desired Cu−Cu dual sites. [ABSTRACT FROM AUTHOR]

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]

The Chemical Communications journal, published by The Royal Society of Chemistry, features a variety of research articles on topics such as luminescent lanthanide metallopeptides, CO2 electrolysis, and supramolecular palladium complexes for cancer therapy. The journal covers a range of scientific discoveries in the field of chemistry, including studies on high-entropy alloy nanomaterials, asymmetric radical reactions, and novel nitrogen-doped porous carbon nanospheres for supercapacitors. The articles provide valuable insights into cutting-edge research in the chemical sciences, showcasing innovative approaches and applications in the field. [Extracted from the article]

Comprehensive Summary: Cu‐catalyzed electrochemical CO2 reduction reaction (CO2RR) and CO reduction reaction (CORR) are of great interest due to their potential to produce carbon‐neutral and value‐added multicarbon (C2+) chemicals. In practice, CO2RR and CORR are typically operated at industrially relevant current densities, making the process exothermal. Although the increased operation temperature is known to affect the performance of CO2RR and CORR, the relationship between temperatures and kinetic parameters was not clearly elaborated, particularly in zero‐gap reactors. In this study, we detail the effect of the temperature on Cu‐catalyzed CO2RR and CORR. Our electrochemical and operando spectroscopic studies show that high temperatures increase the activity of CO2RR to CO and CORR to C2H4 by enhancing the mass transfer of CO2 and CO. As the rates of these two processes are highly influenced by reactant diffusion, elevating the operating temperature results in high local CO2 and CO availability to accelerate product formation. Consequently, the *CO coverage in both cases increases at higher temperatures. However, under CO2RR conditions, *CO desorption is more favorable than carbon‐carbon (C—C) coupling thermodynamically at high temperatures, causing the reduction in the Faradaic efficiency (FE) of C2H4. In CORR, the high‐temperature‐augmented CO diffusion overcomes the unfavorable adsorption thermodynamics, increasing the probability of C—C coupling. [ABSTRACT FROM AUTHOR]

Using low and optimized magnetic field along with electric field is a novel strategy to facilitate electrochemical nitrite reduction reaction (NO2RR). Herein, the magnetic field assisted electrocatalytic ammonia synthesis employing spin‐thrusted β‐MnPc at 95 mT magnetic field is explored. The calculated rate of ammonia generation is 16603.4 µg h−1 mgcat−1, which is almost twice that of the nonpolarized manganese phthalocyanine (MnPc) catalyst. Additionally, the Faradaic efficiency (FE) at –0.9 V versus RHE is found to be 92.9%, significantly higher compared to the nonpolarized MnPc catalyst. In presence of external magnetic field, MnPc catalysts provide a better electron transfer channel which results in a lower charge transfer resistance and hence better electrochemical performances. Density functional theory (DFT) result further verifies that magnetic field induced β‐MnPc has a lower potential barrier (0.51 eV) for the protonation of NO* than nonpolarized β‐MnPc (1.08 eV), which confirms the enhanced electrochemical nitrite reduction to ammonia. [ABSTRACT FROM AUTHOR]

Transition metal and nitrogen co‐decorated carbon materials are promising platforms for CO2 electroreduction. A hard‐template 2‐step pyrolysis method is proposed for the fabrication of highly dispersed Ni and Cu atomic active sites on a 3D macroporous carbon matrix. The pyrrolic N‐type Ni−Nx sites serve as dominant active sites toward selective CO2 electroreduction to CO. The incorporation of Cu alters the distribution of N species and simultaneously optimizes the electronic state and geometric structure of the Ni−Nx moiety, thereby improving its adsorption and activation capacity for CO2. Moreover, the isolated Cu atomic sites enhance the resistance of corresponding gas‐diffusion electrodes against electrolyte flooding. The optimal catalyst 3D NiCu‐69 achieves nearly exclusive production of CO with a Faraday efficiency (FECO) of 98% at a current density of −700 mA cm−2 in a CO2‐gas‐fed flow‐through electrolyzer and delivers a CO production rate of 1363 mol(m2s)−1, which is exceeding most reported electrocatalysts. The FECO remained as high as 94% after electrolyzing at a current density of −100 mA cm−2 for 22 h. 3D NiCu‐69 exhibits a favorable performance in both acidic and neutral conditions, with a high FECO of ≈90.2% within the current density range of −100 to −500 mA cm−2. [ABSTRACT FROM AUTHOR]

This study presents the electrochemical reduction of graphene oxide (GO) to reduced graphene oxide (rGO) directly onto flexible interdigitated gold electrodes and its application as a strain sensor. GO reduction is achieved using cyclic voltammetry (CV). Remarkably, only a single CV cycle transformed GO into rGO to obtain low‐resistance (≈100 Ω) devices. The reduction of GO is confirmed using Raman spectroscopy and electrical measurements. rGO on flexible interdigitated gold electrodes exhibits graphene‐like characteristics when used as electrolyte‐gated field‐effect transistors. The fabricated devices display a gauge factor (GF) of ≈3.7 in the 0–794 με range. This value represents a substantial improvement, ≈60% higher than traditional metallic strain sensors, which have a GF of ≈2.1. Most importantly, the rGO strain sensor exhibits fast response (1.1 s) and recovery (0.92 s) times. The rGO sensor is mounted on a clamp with an adjustable diameter, which reveals exceptional flexibility and bendability without damage or degradation. These results highlight the potential of rGO for advancing strain‐sensing applications, offering promising opportunities for the future of this technology. [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]

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]

Title hybrid iron(II)- and cobalt(III)-centered complexes were prepared in moderate yields using the template reactions of 3-acetylpyrazoloxime as a chelating ligand synthon with a Lewis-acidic zirconium or hafnium(IV) phthalocyaninate on the corresponding 3d-metal ion as a matrix. Formation of the cobalt(III)-centered complexes is observed due to the oxidation of Co2+ cations of the initial cobalt(II) salt. Thus obtained binuclear chloride H-bonded iron(II) and cobalt(III) compounds were characterized using elemental analysis, 1H and 13C {1H} NMR, MALDI-TOF mass, 57Fe Mössbauer (for iron compounds) and UV-vis spectra, and by single-crystal X-ray diffraction (XRD). Their redox properties were studied by cyclic (CV) and differential pulse voltammetry methods, and using spectroelectrochemical experiments. Their encapsulated 3d-metal ions with the electronic d6 configuration are located almost in the center of MN6-coordination polyhedra, the geometry of which is more closer to a trigonal antiprism (TAP, the distortion angle ϕ = 60°) than to a trigonal prism (TP, ϕ = 0°) with ϕ ∼ 40°. FeII–N distances fall in the range 1.913(6)–1.965(7) Å, while the CoIII–N bond lengths are from 1.890(8) to 1.935(8) Å. The geometry of MIVO3N4-coordination polyhedra of their capping metal(IV) ions is intermediate between a capped TAP and a capped TP. In the molecules of ZrIVMIIIMIIMIIZrIV-pentanuclear intracomplexes, (HS)FeIII–N and (LS)CoIII–N distances in their two semiclathrochelate fragments fall in the ranges 1.915(10)–1.980(12) Å and 1.886(13)–1.930(13) Å, respectively, and the geometry of MN6-coordination polyhedra is closer to a TAP (values of ϕ are higher than 30°). The geometry of MN6-polyhedra of the HS cross-linking metal(II) ions between them is close to a TAP (values of ϕ are higher than 50°). All the obtained binuclear hybrid complexes exhibit very similar electrochemical patterns. Their CVs contain quasi-reversible or irreversible three reduction and three oxidation waves. The potentials of electrochemical reductions, assigned to the Pc-localized redox processes, are close to each other. The first of them is a quasi-reversible process attributed to the Pc-based one-electron reduction, while the first oxidation wave was assigned to the metal-centered M2+/3+ redox couples. The spectroelectrochemical data confirmed an assignment of the aforementioned electrochemical processes. [ABSTRACT FROM AUTHOR]

The production of ammonia (NH3) from nitrogen sources involves competitive adsorption of different intermediates and multiple electron and proton transfers, presenting grand challenges in catalyst design. In nature nitrogenases reduce dinitrogen to NH3 using two component proteins, in which electrons and protons are delivered from Fe protein to the active site in MoFe protein for transfer to the bound N2. We draw inspiration from this structural enzymology, and design a two‐component metal–sulfur–carbon (M−S−C) catalyst composed of sulfur‐doped carbon‐supported ruthenium (Ru) single atoms (SAs) and nanoparticles (NPs) for the electrochemical reduction of nitrate (NO3−) to NH3. The catalyst demonstrates a remarkable NH3 yield rate of ~37 mg L−1 h−1 and a Faradaic efficiency of ~97 % for over 200 hours, outperforming those consisting solely of SAs or NPs, and even surpassing most reported electrocatalysts. Our experimental and theoretical investigations reveal the critical role of Ru SAs with the coordination of S in promoting the formation of the HONO intermediate and the subsequent reduction reaction over the NP‐surface nearby. Such process results in a more energetically accessible pathway for NO3− reduction on Ru NPs co‐existing with SAs. This study proves a better understanding of how M−S−Cs act as a synthetic nitrogenase mimic during ammonia synthesis, and contributes to the future mechanism‐based catalyst design. [ABSTRACT FROM AUTHOR]

The electrochemical nitrogen reduction reaction (eNRR) is a crucial process for the sustainable production of ammonia (NH3) for energy and agriculture applications. However, the reaction's efficiency is highly dependent on the activation of the inert N≡N bond, which is hindered by the electron back‐donation to the π* orbitals of the N≡N bond, resulting in low eNRR capacity. Herein, we report a main‐group metal‐nonmetal (O−In−S) eNRR catalyst featuring a dynamic proton bridge, with In−S serving as the polarization pair and O functioning as the dynamic electron pool. In situ spectroscopic analysis and theoretical calculations reveal that the In−S polarization pair acts as asymmetric dual‐sites, polarizing the N≡N bond by concurrently back‐donating electrons to both the πx* and πy* orbitals of N2, thereby overcoming the significant band gap limitations, while inhibiting the competitive hydrogen evolution reaction. Meanwhile, the O dynamic electron pool acts as a "repository" for electron storage and donation to the In−S polarization pair. As a result, the O−In−S dynamic proton bridge exhibits exceptional NH3 yield rates and Faradaic efficiencies (FEs) across a wide potential window of 0.3 V, with an optimal NH3 yield rate of 80.07±4.25 μg h−1 mg−1 and an FE of 38.01±2.02 %, outperforming most previously reported catalysts. [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]

It is still a great challenge to achieve high selectivity of ethanol in CO2 electroreduction reactions (CO2RR) because of the similar reduction potentials and lower energy barrier of possible other C2+ products. Here, we report a MOF‐based supported low‐nuclearity cluster catalysts (LNCCs), synthesized by electrochemical reduction of three‐dimensional (3D) microporous Cu‐based MOF, that achieves a single‐product Faradaic efficiency (FE) of 82.5 % at −1.0 V (versus the reversible hydrogen electrode) corresponding to the effective current density is 8.66 mA cm−2. By investigating the relationship between the species of reduction products and the types of catalytic sites, it is confirmed that the multi‐site synergism of Cu LNCCs can increase the C−C coupling effect, and thus achieve high FE of CO2–to–ethanol. In addition, density functional theory (DFT) calculation and operando attenuated total reflectance surface‐enhanced infrared absorption spectroscopy further confirmed the reaction path and mechanism of CO2–to–EtOH. [ABSTRACT FROM AUTHOR]

The continuous growth in global energy demand has led to extensive burning and overconsumption of fossil fuels, resulting in a rapid increase in greenhouse gas emissions, primarily carbon dioxide. On one hand, the frequency and intensity of extreme weather events have increased dramatically due to global climate change. On the other hand, renewable energy sources are rapidly developing. Therefore, CO 2 electrochemical reduction technology has attracted considerable attention as a sustainable solution for converting CO 2 into valuable chemicals. Copper-based catalysts can efficiently reduce CO 2 directly to high-value chemicals, making them one of the focal points in CO 2 electrochemical reduction (eCO 2 RR) research. Many factors influence the activity and selectivity of eCO 2 RR, and this paper systematically reviews the recent advances in CO 2 electrochemical reduction using Cu-based catalysts. Firstly, the fundamental principles and reaction mechanisms of CO 2 electrochemical reduction are outlined. Subsequently, the discussion delves into Cu catalyst structures and composition synergistic control strategies, covering monometallic copper catalysts, multimetallic copper-based catalysts, copper oxides and their derived catalysts, and copper-organic composite catalysts. Finally, we also analyzed the challenges faced by Cu-based catalyst research and provided an outlook on the prospects of CO 2 electroreduction technology in conjunction with emerging AI technology. • Summarized the mechanisms of C 1 and C 2+ products in eCO 2 RR. • Summarized the application of five types of copper-based catalysts in eCO 2 RR. • Discussed the development prospects and strategies of eCO 2 RR in combination with AI. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of nitrate toward ammonia under mild conditions addresses many challenges of the Haber-Bosch reaction, providing a sustainable method for ammonia synthesis, yet it is limited by sluggish reduction kinetics and multiple competing reactions. Here, the titanium hydride electrocatalyst is synthesized by electrochemical hydrogenation reconstruction of titanium fiber paper, which achieves a large ammonia yield rate of 83.64 mg h−1 cm−2 and a high Faradaic efficiency of 99.11% with an ampere-level current density of 1.05 A cm−2 at −0.7 V versus the reversible hydrogen electrode. Electrochemical evaluation and kinetic studies indicate that the lattice hydrogen transfer from titanium hydride promotes the electrocatalytic performance of nitrate reduction reaction and the reversible equilibrium reaction between lattice hydrogen and activate hydrogen not only improves the electrocatalytic activity of nitrate reduction reaction but also demonstrates notable catalytic stability. These finding offers a universal design principle for metal hydrides as catalysts for effectively electrochemical ammonia production, highlighting their potential for sustainable ammonia synthesis. The electrocatalytic reduction of nitrate to ammonia offers a sustainable alternative to the Haber-Bosch process. Here, the authors report a lattice hydrogen transfer mechanism that enhances electrocatalytic activity by enabling reversible equilibrium reactions between lattice and active hydrogen. [ABSTRACT FROM AUTHOR]

This work presents the results of a study on the effect of ionic surfactants: cationic hexadecyltriammonium bromide (CTAB) and anionic sodium salt of sulfonic acid (1OSASS) on the Bi(III) electroreduction process in mixed aqueous–organic supporting electrolyte solutions containing methanol. This study showed that the composition of the supporting electrolyte solution, particularly the methanol and surfactant concentrations, significantly affects the mechanism and rate of the Bi(III) ion electroreduction. Analysis of the influence of the indicated factors on the mechanisms and kinetics of metal ion electroreduction can contribute not only to the optimization of industrial electrochemical processes but also to the development of innovative technological solutions, such as advanced electrochemical materials and novel sensors. In these experiments, an innovative electrode made of cyclic renewable liquid silver amalgam (R-AgLAFE) was used as a working electrode, which stands out among classic mercury electrodes (HMDE type) due to the significant reduction in mercury consumption while maintaining similar performance. [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]

The electrochemical reduction of a series of nitro-substituted benzenesulfonyl chlorides is investigated. The results of the electrochemical study are analysed with the assistance of theoretical calculations. The study shows that the electron transfer mechanism depends on the position of the nitro substituent on the phenyl ring. The 3-nitrobenzenesulfonyl chloride follows a stepwise mechanism where the reduction leads to an intermediate radical anion. For the 4-nitrobenzenesulfonyl chloride, 2-nitrobenzenesulfonyl chloride, and 2,4-nitrobenzenesulfonyl chloride, the reduction follows a "sticky" dissociative mechanism, where the electron transfer and S–Cl bond cleavage are concerted. The dissociation products (arylsulfinyl radical and chloride anion) show strong interactions. The difference in behaviour is associated with the overlap of the π* orbital and the S–Cl σ* orbital for the latter three compounds. The through resonance stability of the arylsulfinyl radicals for the para and ortho nitro-substituted compounds facilitates the dissociation of the reduced structures. Upon reduction, the 3-nitrobenzenesulfonyl chloride and 4-nitrobenzenesulfonyl chloride, also produce the corresponding diaryl disulfones, which are easier to reduce that the parent molecules and hence induce an interesting autocatalytic mechanism. Such a mechanism, which depends on the concentration and the scan rate, does not take place with the 2-nitrobenzenesulfonyl chloride and 2,4-dinitrobenzenesulfonyl chloride due to the sterical hindrance of the nitro substituent at the ortho position, as it prevents the formation of the disulfones. [ABSTRACT FROM AUTHOR]

The attenuated total reflection-surface-enhanced infrared absorption spectroscopy (SEIRAS) activity of electrodeposited Cu nanoparticles on indium tin oxide-modified Si internal reflection elements is reported. The solution in the cell is easily, and repeatedly, exchanged between a copper deposition bath and a solution containing 4-methoxypyridine through the use of a flow-through spectroelectrochemical cell. 4-methoxypyridine is a convenient SEIRAS probe molecule exhibiting potential-dependent adsorption/desorption on the copper surface. Successive amounts of copper are deposited and then evaluated for electrochemical SEIRAS activity without the need to expose the Cu surface to ambient conditions. It is found that copper deposition charge densities of approximately 60 mC cm−2 exhibit the largest amplitude and most symmetric IR absorption peaks of the investigated electrodeposition conditions. Scanning electron microscopy images of the different Cu charge density films are correlated with the SEIRAS results and establish that close-packed two-dimensional, percolated arrays of oblate, ellipsoidal Cu nanoparticles are responsible for ideal SEIRAS performance and three-dimensional aggregates of larger particles should be avoided. Textured films of Cu nanoparticles are used to determine the adsorbed species present on the copper surface during CO2 electroreduction at low overpotentials. Evidence of adsorbed CO and COH is found at lower overpotentials than those described in previous reports. [ABSTRACT FROM AUTHOR]

The self-doping of oxygen vacancy and Ti3+ by electrochemical reduction (ER) method has been proved to be an effective means to improve the PEC performance of TiO2. However, the effect of the surface structure on ER treatment remains ambiguous. In this work, three kinds of nanostructured rutile TiO2 (nanowire arrays (TNWs), etched nanowire arrays (E-TNWs) and nanorod arrays (TNRs)) were reduced electrochemically to explore the factors influencing the ER process of rutile TiO2. The experimental results show that alkaline environment (1 M NaOH) is more conducive to the occurrence of ER reaction. And the reduced three kinds of nanostructured TiO2 photoanodes show a significantly higher photocurrent density of about 1.46, 1.65 and 1.45 mA cm−2 at 1.23 V vs. relative hydrogen electrode (RHE), respectively, which are 15, 16 and 1.1 times that of pristine TiO2. The different degrees of photocurrent density enhancement can be ascribed to the different degrees of electrochemical reduction of TiO2 with different crystallinity and exposed crystal facets as well as specific surface area. This study provides new insights into the mechanism of electrochemical reduction method. [ABSTRACT FROM AUTHOR]

The electrochemical nitrate reduction for green ammonia production is attracting increasing attention, where the catalysts are widely investigated by controlling the compositions or structures to achieve high performance. However, their reconstructions under reduction potentials are inevitable and uncontrollable, leading to uncertain performance, and a confused understanding of the mechanism. In this work, a strategy is proposed by controlling the pre‐catalyst's reconstruction chemistry toward electrochemical nitrate reduction reaction (e‐NO3RR) with superior activity and stability. To demonstrate the idea, a pre‐catalyst is fabricated with α‐Co(OH)2 and Cu(OH)2 (α‐Co(OH)2/Cu(OH)2), which is in situ reconstructed to a tandem catalyst with Cu and β‐Co(OH)2 (Cu/β‐Co(OH)2) under working potential. Cu/β‐Co(OH)2 achieves an optimal Faraday efficiency for ammonia of 97.7% with a yield rate of 3.9 mmol h−1 cm−2 at −0.5 V, outperforming other reported metal‐hydroxide catalysts. The experimental and theoretical results demonstrate that a tandem catalytic mechanism is responsible for the exceptional performance: 1) Cu functions as the donor of nitrite; and 2) β‐Co(OH)2 serves as active sites for generating active hydrogen and reducing nitrogen‐containing groups. This work highlights that the controllable reconstruction toward improved performance can be realized, and provides an insightful understanding of the mechanism, which is helpful for developing active and stable catalysts for various catalytic applications. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) synthesis via nitrogen reduction reaction under mild conditions is challenging due to the difficulty of activating nitrogen. Herein, Mn-doped g-C3N4 (x-Mn-CN, x = 5, 10, and 15) catalysts with efficiency NRR performance were synthesized. The resulting 5-Mn-CN exhibits higher NRR performance (NH3 yield rate: 15.2 μg h−1 mgcat−1, Faradaic efficiency: 7.1%) at -0.4 V (vs. RHE) than others. It is found that the active sites of Mn3+ are generated by electron transfer from Mn2+ to the N of g-C3N4, and active N2 through the π back-donation process. This is evidenced by the experimental result that the NH3 yield rate of 5-Mn-CN significantly decreases from 15.2 μg h−1 mgcat−1 to 2.6 μg h−1 mgcat−1 after lowering the concentration of Mn3+. The concentration of Mn3+ is reduced by treating the catalyst in the ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) solution. This study enhances the understanding of N2 activation and provides insights into the transition metal-doped g-C3N4 as NRR catalysts. [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]

By adjusting the synthesis variation of hollow urchin-like Ni-NC(HU)-x catalyst, the content of pyridinic-N was adjusted, and the dual-atoms site was formed. Ni-NC(HU)-50 showed the best catalytic performance with FE CO of 97.2% at −0.9 V vs. RHE and sustains above 95% within 50 h. [Display omitted] Dual-atoms catalysts (DACs), while inheriting the advantages of maximum atom utilization ratio and excellent selectivity of single-atom catalysts (SACs), can better enhance the catalytic activity through the synergy of adjacent atoms. Therefore, DACs are considered to be very potential catalysts for CO 2 to CO conversion. Its catalytic activity is greatly influenced by the coordination environment and morphology. Here, hollow urchin-like Ni N C catalysts (Ni-NC(HU)-x, x = 100, 50, 25, 0) were synthesized using urchin-like nickel particles as template. By adjusting the amount of additional nitrogen source, the percentage content of pyridinic-N was adjusted as well as further affecting the coordination environment. Among them, Ni-NC(HU)-50, which had the highest content of pyridinic-N, formed a dual-atoms coordination structure and had the best catalytic performance that the CO Faradaic efficiency (FE CO) reached 97.2 % at −0.9 V vs. reversible hydrogen electrode (RHE) and sustained above 95 % within 50 h. In-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations showed that Ni-NC(HU)-50 exhibited the best performance of CO 2 reduction reaction (CO 2 RR) by lowering the *COOH formation free energy barrier and its favorable dual desorption mechanism of *CO L and *CO B. [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 self-doping of oxygen vacancy and Ti3+ by electrochemical reduction (ER) method has been proved to be an effective means to improve the PEC performance of TiO2. However, the effect of the surface structure on ER treatment remains ambiguous. In this work, three kinds of nanostructured rutile TiO2 (nanowire arrays (TNWs), etched nanowire arrays (E-TNWs) and nanorod arrays (TNRs)) were reduced electrochemically to explore the factors influencing the ER process of rutile TiO2. The experimental results show that alkaline environment (1 M NaOH) is more conducive to the occurrence of ER reaction. And the reduced three kinds of nanostructured TiO2 photoanodes show a significantly higher photocurrent density of about 1.46, 1.65 and 1.45 mA cm−2 at 1.23 V vs. relative hydrogen electrode (RHE), respectively, which are 15, 16 and 1.1 times that of pristine TiO2. The different degrees of photocurrent density enhancement can be ascribed to the different degrees of electrochemical reduction of TiO2 with different crystallinity and exposed crystal facets as well as specific surface area. This study provides new insights into the mechanism of electrochemical reduction method. [ABSTRACT FROM AUTHOR]

Zinc metal stands out as a promising anode material due to its exceptional theoretical capacity, impressive energy density, and low redox potential. However, challenges such as zinc dendrite growth, anode corrosion, and side reactions in aqueous electrolytes significantly impede the practical application of zinc metal anodes. Herein, 3‐(1‐pyridinio)‐1‐propanesulfonate (PPS) is introduced as a zwitterionic additive to achieve long‐term and highly reversible Zn plating/stripping. Due to the orientation polarization with the force of electric field, PPS additive with π–π conjugated pyridinio cations and strong coordination ability of sulfonate anion tends to generate a dynamic adsorption layer and build a unique water–poor interface. PPS with steric hindrance effect and strong coordination ability can attract solvated Zn2+, thereby promoting the desolvation process. Moreover, by providing a large number of nucleation sites and inducing zinc ion flow, the preferred orientation of the (002) crystal plane can be achieved. Therefore, the interfacial electrochemical reduction kinetics is regulated and uniform zinc deposition is ensured. Owing to these advantages, the Zn//Zn symmetrical cell with PPS additive exhibits remarkable cycling stability exceeding 2340 h (1 mA cm−2 and 1 mA h cm−2). The Zn//V2O5 full cell also delivers stable cycling for up to 6000 cycles. [ABSTRACT FROM AUTHOR]

Emerging as a new class of two‐dimensional materials with atomically thin layers, MBenes have great potential for many important applications such as energy storage and electrocatalysis. Toward mitigating carbon footprint, there has been increasing interest in CO2/CO conversion on MBenes, but mostly focused on C1 products. C2+ chemicals generally possess higher energy densities and wider applications than C1 counterparts. However, C–C coupling is technically challenging because of high energy requirement and currently few catalysts are suited for this process. Here, we explore electrochemical CO reduction reaction to C2 chemicals on Mo2B2O2 MBene via density‐functional theory calculations. Remarkably, the most favorable CO–COH coupling is revealed to be a spontaneous and barrierless process, making Mo2B2O2 an efficient catalyst for C–C coupling. Among C1 and C2 chemicals, ethanol is predicted to be the primary product. Furthermore, by charge and bond analysis, it is unraveled that there exist significantly more unbonded electrons in the C atom of intermediate *COH than other C1 intermediates, which is responsible for the facile C–C coupling. From an atomic scale, this work provides microscopic insight into C–C coupling process and suggests Mo2B2O2 a promising catalyst for electrochemical CO reduction to C2 chemicals. [ABSTRACT FROM AUTHOR]

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Ammonia (NH3) synthesis via nitrogen reduction reaction under mild conditions is challenging due to the difficulty of activating nitrogen. Herein, Mn-doped g-C3N4 (x-Mn-CN, x = 5, 10, and 15) catalysts with efficiency NRR performance were synthesized. The resulting 5-Mn-CN exhibits higher NRR performance (NH3 yield rate: 15.2 μg h−1 mgcat−1, Faradaic efficiency: 7.1%) at -0.4 V (vs. RHE) than others. It is found that the active sites of Mn3+ are generated by electron transfer from Mn2+ to the N of g-C3N4, and active N2 through the π back-donation process. This is evidenced by the experimental result that the NH3 yield rate of 5-Mn-CN significantly decreases from 15.2 μg h−1 mgcat−1 to 2.6 μg h−1 mgcat−1 after lowering the concentration of Mn3+. The concentration of Mn3+ is reduced by treating the catalyst in the ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) solution. This study enhances the understanding of N2 activation and provides insights into the transition metal-doped g-C3N4 as NRR catalysts. [ABSTRACT FROM AUTHOR]

The discharge capacities and rate capability of TiNb2O7 powders were enhanced through the additional postreduction treatment. X‐ray photoelectron spectroscopy and electron paramagnetic resonance results confirmed the formation of oxygen vacancies in TiNb2O7 powders after a reduction treatment. The appearance of oxygen vacancies in TiNb2O7 powders formed the impurity level in the forbidden gap and decreased the bandgap values of TiNb2O7. Compared with the pristine TiNb2O7 powders, when TiNb2O7 powders were reduced at 400°C for 40 min, the charge transfer resistance of prepared samples was reduced from 43.67 to 19.35 Ω, and the pseudocapacitive contribution of TiNb2O7 was increased from 44% to 59%. In addition, the discharge capacities at 0.1 and 20 C of prepared batteries were increased by 10.84% and 105.85%, respectively. On the other hand, increasing the temperature in the reduction treatment caused the formation of Ti4+/Ti3+ and Nb5+/Nb4+ pairs and decreased the amounts of available redox couples, thereby deteriorating the electrochemical performance of prepared batteries. The results in the present study revealed that the discharge capacities and rate capability of TiNb2O7 powders were enhanced through a postreduction treatment. [ABSTRACT FROM AUTHOR]

Efficient electrochemical CO2 reduction reaction (CO2RR) requires advanced gas‐diffusion electrodes (GDEs) with tunned microenvironment to overcome low CO2 availability in the vicinity of catalyst layer. Herein, for the first time, pyridine‐containing microgels‐augmented CO2 availability is presented in Cu2O‐based GDE for high‐rate CO2 reduction to ethylene, owing to the presence of CO2‐phil microgels with amine moieties. Microgels as three‐dimensional polymer networks act as CO2 micro‐reservoirs to engineer the GDE microenvironment and boost local CO2 availability. The superior ethylene production performance of the GDE modified by 4‐vinyl pyridine microgels, as compared with the GDE with diethylaminoethyl methacrylate microgels, indicates the bifunctional effect of pyridine‐based microgels to enhance CO2 availability, and electrocatalytic CO2 reduction. While the Faradaic efficiency (FE) of ethylene without microgels was capped at 43% at 300 mA cm−2, GDE with the pyridine microgels showed 56% FE of ethylene at 700 mA cm−2. A similar trend was observed in zero‐gap design, and GDEs showed 58% FE of ethylene at −4.0 cell voltage (>350 mA cm−2 current density), resulting in over 2‐fold improvement in ethylene production. This study showcases the use of CO2‐phil microgels for a higher rate of CO2RR‐to‐C2+, opening an avenue for several other microgels for more selective and efficient CO2 electrolysis. [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]

Ethylene (C2H4) electrosynthesis from the electrocatalytic CO2 reduction process holds enormous potential applications in industrial production. However, the sluggish kinetics of C─C coupling often result in low yield and poor selectivity for C2H4 production. Herein, the performance of Cu catalysts of varying sizes is investigated, prepared via a cryo‐mediated liquid phase exfoliation technique, for the electrochemical CO2 reduction to C2H4. The activity and selectivity of C2H4 gradually increase as the size of the Cu catalysts decreases from tens of nanometers to a few nanometers. Impressively, the 5 nm Cu quantum dots (Cu‐5) achieve a maximum C2H4 Faradaic efficiency (FE) of 81.5% and a half‐cell cathodic energy efficiency (CEE) of 42.2% with a large partial current density of 1.1 A cm−2 at −0.93 V versus the reversible hydrogen electrode. Structural characterization and in situ spectroscopic analysis reveal that the Cu‐5 quantum dots, dominated by the (100) facet, provide an abundance of active sites that enhance CO2 adsorption and activation, promoting the formation of *CO intermediates. The accumulation of *CO intermediates on the Cu active sites facilitates the CO‐CHO coupling reaction, thus enhancing the C2H4 production rate. [ABSTRACT FROM AUTHOR]

Herein, a pyrolysis-induced precursor transformation strategy has been proposed. Using pre-synthesized PDA-M as a precursor, the production of transition metal single atom catalysts (SACs) has been achieved, with compositional flexibility at high metal loadings. In particular, the Ni SAC sample has shown promising CO selectivity when evaluated for the electrochemical CO2 reduction reaction, reaching 29.8 mA cm−2 CO partial current density and 90.3% CO faradaic efficiency at −1.05 V vs. RHE. [ABSTRACT FROM AUTHOR]

In the electrochemical CO2 reduction reaction (CO2RR), transition metal atoms embedded in carbon and nitrogen materials are widely used as highly efficient catalysts because of their excellent catalytic activity and maximum atomic utilization. In this study, we used density functional theory (DFT) to screen catalysts with both thermodynamic and electrochemical stability of Fe–C3N5, Co–C3N5, Ni–C3N5 and Cu–C3N5 from 3d transition metal atoms embedded in C3N5 (TM–C3N5, TM = Sc–Zn). The adsorption and activation of CO2 on the four catalysts were analyzed by means of Bader charge and projected density of states (PDOS). The ultimate potential (UL) and crystal orbital Hamilton population (COHP) analysis showed that the dominant product of CO2 on Fe–C3N5 and Ni–C3N5 was HCOOH, with excellent activity and selectivity. Cu–C3N5 has good ability to reduce CO2 to CH3OH. At the same time, Fe–C3N5, Ni–C3N5 and Cu–C3N5 can effectively inhibit the occurrence of the HER. [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]

Electrochemical CO2 reduction reaction (CO2RR) coupled with renewable electricity holds promises for efficient mitigation of carbon emission impacts on the environment and turning CO2 into valuable chemicals. One important task in CO2RR development is the design and fabrication of efficient electrodes for stable operation in the long term. Gas‐diffusion electrodes (GDEs) have been employed to continuously feed CO2 to the electrolyzers. Despite significant advances in GDE design and tailoring GDE properties, the present GDEs often suffer from the critical issue of flooding due to the electrowetting of carbon‐based substrates, which hinders the transition to industrial application. To address flooding, GDEs with intrinsically hydrophobic polymeric substrates have been recently fabricated and have shown promising performances. Herein, the advances and challenges associated with carbon‐free GDEs are reviewed for CO2RR. This review first briefly outlines GDE and electrolyzers basics. Through critical discussion around the shortcomings of conventional carbon‐based GDEs, the most recent efforts to resolve flooding are summarized. Subsequently, the advances, advantages, and challenges of carbon‐free GDEs are elaborated. Finally, priorities for future studies are suggested, with the aim to support the advancement and scale‐up of carbon‐free GDEs and extend them to other electrochemical systems where gas and the electrolyte are in contact. [ABSTRACT FROM AUTHOR]