Turnover Frequency Research Articles

V-doped activated Ru/Ti2.5V0.5C2 dual-active center accelerate hydrogen production from ammonia borane

Designing and constructing the active center of Ru-based catalysts is the key to efficient hydrolysis of ammonia borane (NH3BH3, AB) for hydrogen production. Herein, V-doped Ru/Ti2.5V0.5C2 dual-active center catalysts were synthesized, showing excellent catalytic ability for AB hydrolysis. The corresponding turnover frequency value was 1072 min−1 at 298 K, and the hydrolysis rate rB of AB was 235 × 103 mL·min−1·gRu–1. X-ray photoelectron spectroscopy results indicated that the interaction between V-doped Ti3C2 and catalytic metal Ru transfers electrons from Ti to Ru, resulting in electron-rich Ru species. According to density functional theory calculations, the activation energy and reaction dissociation energy of the reactants AB and H2O on V-doped catalysts were lower than those of Ru/Ti3C2, thus optimizing the catalytic kinetics of AB hydrolysis. The modification strategy of V-doped Ti3C2 provides a new pathway for the development of high-performance catalysts for AB hydrolysis.

Boosting catalytic combustion of diesel soot particles over potassium-promoted CoMn-Co3O4 dual spinel structure catalyst

Catalytic oxidation is an effective method to remove soot particles from diesel exhaust, and the key aspect of this technology is to develop highly effective catalysts. In this work, a potassium-promoted dual spinel structure was prepared for soot elimination with the self-sacrificing template strategy. The highest activity was presented by the CoMn-0.2 H-10%K catalyst under a loose contact mode, with the temperature of soot conversion reaching 90% and turnover frequency value of 365 °C and 3.76×10−3 s−1, respectively. The catalyst was found to have a high content of oxygen vacancy and a superior ability for lattice oxygen migration, which led to elevated performance for soot combustion. The formation of K-OMS-2 at the interface between the CoMn spinel and the Co3O4 spinel was one of the reasons for the elevated lattice oxygen migration at low temperatures. This work provides an effective way to prepare transition metal catalysts for soot combustion.

Selective hydrogenation of 5-hydroxymethylfurfural triggered bya high Lewis acidic Ni-based transition metal carbide catalyst

The high-efficiency conversion of biomass resources to biofuels has attracted widespread attention, and the active sites and synergistic effect of catalysts significantly impact their surface arrangement and electronic structure. Here, a nickel-based transition metal carbide catalyst (Ni/TMC) with high Lewis acidity was prepared by self-assembly of transition metal carbide (TMC) and nickel, which exhibited excellent performance on synergistic hydrogenation and hydrogenolysis of 5-hydroxymethylfurfural (HMF) into liquid biofuel 2,5-dimethylfuran (DMF). Notably, Ni/WC with the highest Lewis acidity (4728.3 μmol/g) can achieve 100% conversion of HMF to 97.6% yield of DMF, with a turn-over frequency of up to 46.5 h−1. The characterization results demonstrate that the rich Lewis acid sites yielded by the synergistic effect between Ni species and TMC are beneficial for the CO hydrogenation and C–O cleavage, thereby accelerating the process of hydrodeoxygenation (HDO). Besides, a kinetic model for the HDO of HMF to DMF process has been established based on the experimental results, which elucidated a significant correlation between the measured and the predicted data (R2 > 0.97). Corresponding to the adsorption configuration of Ni/WC and substrate determined by in-situ FTIR characterization, this study provides a novel insight into the selective conversion of HMF process for functional biofuel and bio-chemicals.

Bimetallic Ni-Fe Supported by Gadolinium Doped Ceria (GDC) Catalyst for CO2 Methanation

CO2 conversion into fuels and high value-added chemical feedstocks, such as methane, has gained novel interest as a crucial process for further manufacturing multi-carbon products. Methane, CH4, becomes a promising alternative for environmental and energy supply issues. Nickel-based catalysts were found to be very active and selective for CH4 production. The use of promoter and support material to develop high activity, high selectivity, and durable catalysts for CO2 methanation at low temperature is a challenge. Gadolinium-Doped Ceria (GDC) has been known as material for Solid Oxide Fuel Cell (SOFC) and Solid Oxide Electrolysis Cell (SOEC) due to higher ionic conductivity and lower operating temperatures. However, few researches have been done regarding to CO2 methanation over GDC as catalyst support so far. In this present work, CO2 methanation was investigated over bimetallic Ni-Fe catalyst supported by GDC. The results showed that CH4 production rate by using Ni-Fe/GDC catalyst was higher than that of GDC at all reaction temperatures carried on. Ni-Fe/GDC showed remarkable CH4 production rate as of 17.73 mmol.gcat−1.h−1 at 280 °C. No catalytic activity was produced by GDC catalyst only. The highest CO2 conversion (46.50%) was observed at 280 °C, with almost 100% selectivity to CH4. The turnover frequency (TOF) value of Ni-Fe/GDC (4529.32 h−1) was the highest than that of Ni and common CO2 methanation catalyst, Ni/Al2O3 catalysts at 280 °C, further displaying the outstanding low-temperature catalytic activity. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

In situ green immobilization of palladium nanoparticles onto polydopamine-modified eggshell membrane for catalytic reduction of nitrophenols

4-Nitrophenol (4-NP) poses significant threats to both ecosystems and human health, making it essential and highly beneficial to take effective measures to mitigate its impact. Herein, eggshell membrane (ESM) with mussel-inspired polydopamine coatings (ESM-PDA) was constructed and utilized as a template for the immobilization of Pd NPs, resulting in ESM-PDA-Pd formation. The catalyst ESM-PDA-Pd exhibits exceptional performance in reducing 4-NP, and the TOF (turnover frequency) for ESM-PDA-Pd was determined to be 3.3 × 10−5 mmol·mg−1·min−1. Moreover, ESM-PDA-Pd demonstrates excellent catalytic activity in reducing other nitrophenols, including 2-nitrophenol (0.2196 min−1) and 2,4,6-nitrophenol (0.1177 min−1). Notably, the catalyst demonstrated brilliant recyclability, removing 92.4 % of 4-NP within 20 min after undergoing five consecutive runs. This underscores its potential for sustained and effective use in multiple cycles of nitrophenol reduction reactions. Furthermore, the measured Kapp in various water samples is as follows: ultrapure water (0.135 min−1) > tap water (0.109 min−1) > river water (0.083 min−1), indicating its significant potential for industrial applications.

Ultrafine nickel-rhodium nanoparticles anchored on two-dimensional vanadium carbide for high performance hydrous hydrazine decomposition at mild conditions

The development of heterogeneous supported nanocatalysts with a high kinetics combined with low cost is off importance but remains still challenged for hydrazine hydrate served as a promising hydrogen storage material. Herein, by virtue of surficial functional groups, ultrafine NiRh NPs were monodispersed on the two-dimensional V2C surface via a conventional wet chemical co-reduction. The optimized NiRh/V2C system demonstrates an excellent catalytic performance toward selectively catalyzing dehydrogenation of hydrazine hydrate, affording 100% H2 selectivity with the turnover frequency (TOF) value of 987.5 h−1 at 323 K. Such an enhancement is mainly attributed to synergistic effect of nanosystem, which will optimize local surface energy and promote electron transfer in NiRh/V2C system, thereby improving the kinetic selectivity of catalytic hydrazine hydrate decomposition. This work has provided a facile strategy for developing nanocatalysts with high kinetics that could enable huge industrial applications in the future.

One-pot synthesis of multivariate porphyrinic metal-organic frameworks with the insertion of metallobipyridine and the cooperative catalysis for carbonyl hydrosilylation

A series of multivariate porphyrinic metal-organic frameworks with the insertion of bipyridine were obtained via one-pot synthesis. The single Pt site was introduced into the bipyridine linker of BPy@Co-PCN-224 through post-synthetic metalation. The resultant Pt(BPy)Cl2@M-PCN-224, especially when M was Co(II), could efficiently promote carbonyl hydrosilylation with a turnover number up to 13,140 based on Pt and could be recycled and reused for at least 6 times without a noticeable decrease of activity. Mechanistic studies based on in situ UV–vis, FT-IR and 1H NMR spectra, and kinetic isotope effect (KIE) experiments disclosed that the catalytic reaction was accomplished by the cooperative catalysis of Pt(BPy)Cl2 and Co-PCN-224, in which Pt(BPy)Cl2 was the catalytically active center and meanwhile the Co-PCN-224 could condense and increase the concentrations of ketone molecules in its inner cavities through the interactions between Co-porphyrin and carbonyl group. The plausible reaction pathway was proposed based on density functional theory calculations.

First Application of Non‐Metallic A2B Type Silicon Corrole Complexes in Electrocatalytic Hydrogen Evolution

AbstractIn this study, we have successfully synthesized two non‐metallic‐based silicon corrole complexes (F10C−Si, F10C−CN−Si) and used them as HER electrocatalysts for the first time. Electrochemical studies indicate the electrocatalytic HER may go via EE‐CEEC (E: electron transfer step, C: chemical step) pathway. Notably, it can be seen that the introduction of electron‐withdrawing cyano group on the meso‐phenyl of the corrole macrocycle may enhance the catalytic activity of silicon corrole complexes. In DMF with TsOH as the proton source, F10C−CN−Si exhibits a turnover frequency (TOF) of 331.48 s−1 and a high catalytic efficiency (C.E) of 1.29. Furthermore, the catalytic prowess of the silicon corrole complexes extends to neutral aqueous solution, with F10C−CN−Si achieving a TOF of 52.72 h−1 at an overpotential of 1188 mV. This study extends the application of non‐metallic‐based silicon corrole molecular catalysts in the electrocatalytic HER field.

Ruthenium nanoparticles supported on functionalized carbon nanotubes as high-efficiency catalysts for ammonia borane hydrolysis

Developing high-activity catalysts for the hydrolysis of ammonia borane (NH3BH3; AB) is a crucial and urgent task, which is presently considered an effective strategy for hydrogen generation in the applications of portable proton exchange membrane fuel cells (PEMFCs). In this study, carbon nanotubes (CNTs) were modified by self-growth of metal-organic frameworks (MOFs) on their surfaces. As self-sacrificial templates, the carbonization of cobalt and nitrogen containing MOFs led to the modification of CNT. Subsequently, cobalt was transformed into cobalt phosphide (Co2P) via phosphatization to form Co2P/N co-decorated CNTs (NCP-CNTs). Ru/NCP-CNT catalysts were obtained by loading ruthenium nanoparticles (NPs) using a chemical reduction method and their catalytic performance for H2 production via the hydrolysis of AB was systematically investigated. Ru/NCP-CNTs exhibited excellent catalytic activity, with an initial high turnover frequency (TOF) of 193.9 molH2·molRu−1·min−1 and a low activation energy of 32.4 kJ·mol−1. The incorporation of Ru NPs and their excellent synergistic effect with the NCP-CNT supports can explain the improved performance. This work provides an updated approach for fabricating low-cost and high-efficiency catalysts for the hydrolysis of AB.

Spin-cross interface-inducing ultra-high catalytic activity in Co(OH)xPy-MXene toward alkali-free liquid hydrogen generation

Proclaiming the interfacial active sites of non-noble metals on supported catalysts is a paramount topic. Herein, a spin-cross interface (Co(OH)xPy (x/y=3.2)) in the intimate region between Co(OH)2 and CoP is designed by in situ hydroxylation and P-inducing strategy. An ultra-high catalytic hydrogen generation activity with a turnover frequency of 1640 min−1 is achieved for hydrolysis of ammonia borane (NH3BH3). Both experimental observations and computational simulations reveal that the spin-cross interface dramatically reduces the energy barriers for the dissociation of reactant molecules (NH3BH3 and H2O) to expedite the catalytic activity. The coexistence of active interface and MXene create the ensembles of Co atoms coordinated by OH and P. The construction of active sites of Co(OH)xPy simultaneously boosts the adsorption and dissociation of H2O and NH3BH3 molecules. This research provides new paradigm for the rational design of spin-induced catalysts in the future energy system depending on the activation of multi-molecules.

Modulating the Electronic Structures of Pt on Pt/TiO2 Catalyst for Boosting Toluene Oxidation.

Surface hydroxyl groups commonly exist on the catalyst and present a significant role in the catalytic reaction. Considering the lack of systematical researches on the effect of the surface hydroxyl group on reactant molecule activation, the PtOx/TiO2 and PtOx-y(OH)y/TiO2 catalysts were constructed and studied for a comprehensive understanding of the roles of the surface hydroxyl group in the oxidation of volatiles organic compounds. The PtOx/TiO2 formed by a simple treatment with nitric acid presented greatly enhanced activity for toluene oxidation in which the turnover frequency of toluene oxidation on PtOx/TiO2 was around 14 times as high as that on PtOx-y(OH)y/TiO2. Experimental and theoretical results indicated that adsorption/activation of toluene and reactivity of oxygen atom on the catalyst determined the toluene oxidation on the catalyst. The removal of surface hydroxyl groups on PtOx promoted strong electronic coupling of the Pt 5d orbital in PtOx and C 2p orbital in toluene, facilitating the electron transfers from toluene to PtOx and subsequently the adsorption/activation of toluene. Additionally, the weak Pt-O bond promoted the activation of surface lattice oxygen, accelerating the deep oxidation of activated toluene. This study clarifies the inhibiting effect of surface hydroxyl groups on PtOx in toluene oxidation, providing a further understanding of hydrocarbon oxidation.

In silico and in vitro study of pyrimidones synthesized with ethylenediamine- modified β-cyclodextrin: potential against ESBL E. coli

Modern organic synthesis is primarily focused on developing environmentally benign synthetic protocols by employing green chemistry principles. Accordingly, in our recent research work, we herein report the use of modified supramolecular host cyclodextrin as an effective solid based green catalyst for accessing structurally diverse and medicinally relevant pyrimidone architectures. The catalyst and the synthesized compounds 4 (a-r) were characterized using FT-IR, NMR and GC-mass spectroscopy. Major highlights of the reported work include the economical atom process, remarkably gentler reaction conditions, ease of operation, high isolated yields, and excellent catalyst turnover numbers. The molecular docking studies suggest that the compound 4n has hydrogen bonding, hydrophobic and π-pair interactions with the active site of the CXT M 15 receptor. Further, the in-vitro antibacterial study as well as the screening of anti-biofilm activity resulted in a BIC value of 76.79 ± 0.785% at a concentration of 10 µg/mL and morphological alterations induced by DHPMs against the ESBL E. coli strain aggregated with a good result. KEY WORDS: Ethylenediamine modified β-CD, Multicomponent reaction, 3,4-dihydropyrimidin-2(1H)-ones DHPM derivatives, Solvent-free conditions, Reusability, Antibactercidal Bull. Chem. Soc. Ethiop. 2024, 38(4), 1103-1118. DOI: https://dx.doi.org/10.4314/bcse.v38i4.23

Continuous kinetics of 2-hydroxyisobutryic acid esterification using solid acid granular and monolithic activated carbon catalysts

Kinetics of 2-hydroxyisobutyric acid (2-HIBA) esterification with ethanol was studied using sulfonated carbon catalysts in granular (sGAC) and monolith (sACM) forms in a continuous flow packed bed reactor. 2-HIBA is a potential biobased carboxylic acid and its ester a sustainably produced industrial solvent. The catalyst monolith form, made from renewable carbon, offers significantly higher space time yields and conversions, yet little kinetic data or models are available for its use, especially under non-ideal conditions. The effect of ethanol/2-HIBA molar ratio (44, 10, 3.6 and 1.5) at different liquid residence times (3–9 min) was investigated using sGAC. Kinetics of sACM esterifications were investigated at a molar ratio of 3.6 by varying the residence time (2–7 min) and compared with the sGAC. The sACM displayed higher ester yields, acid conversions, and significantly higher reaction rates and space–time-yields (2.1–2.8 ×) compared to the sGAC due to higher surface area to volume ratio. The sACM reaction rates and turnover frequency were comparable to solid acid resins and sulfated silica and zirconia. Pseudo-homogeneous, Eley-Rideal and Langmuir-Hinshelwood models were applied to fit the kinetic data, and the reaction system parameters were obtained through regression analysis. The LH dual active site model resulted in the lowest mean relative error for both 2-HIBA and ester concentration residuals. Adsorption/desorption equilibrium constants for 2-HIBA, ethanol, and ester, were higher compared to water suggesting hydrophobic regions in the sGAC/sACM. Estimation of the external and internal mass transfer criteria indicated negligible effects of mass transfer. With further development sACM and the kinetic model can be used for reactor design of continuous esterification processes using solid acid monolith catalysts.

Study on Water Splitting of the 214-Type Perovskite Oxides LnSrCoO4 (Ln = La, Pr, Sm, Eu, and Ga).

We present a study on the electrocatalysis of 214-type perovskite oxides LnSrCoO4 (Ln = La, Pr, Sm, Eu, and Ga) with semiconducting-like behavior synthesized using the sol-gel method. Among these five catalysts, PrSrCoO4 exhibits the optimal electrochemical performance in both the oxygen evolution reaction and the hydrogen evolution reaction, mainly due to its larger electrical conductivity, mass activity, and turnover frequency. Importantly, the weak dependency of LSV curves in a KOH solution with different pH values, revealing the adsorbate evolving mechanism in PrSrCoO4, and the density functional theory (DFT) calculations indicate that PrSrCoO4 has a smaller Gibbs free energy and a higher density of states near the Fermi level, which accelerates the electrochemical water splitting. The mutual substitution of different rare-earth elements will change the unit-cell parameters, regulate the electronic states of catalytic active site Co ions, and further affect their catalytic performance. Furthermore, the magnetic results indicate strong spin-orbit coupling in the electroactive sites of Co ions in SmSrCoO4 and EuSrCoO4, whereas the magnetic moments of Co ions in the other three catalysts mainly arise from the spin itself. Our experimental results expand the electrochemical applications of 214-type perovskite oxides and provide a good platform for a deeper understanding of their catalytic mechanisms.

Carbonized cellulose microspheres loaded with Pd NPs as catalyst in p-nitrophenol reduction and Suzuki-Miyaura coupling reaction

Catalytic reduction of p-nitrophenol is usually carried out using transition metal nanoparticles such as gold, palladium, silver, and copper, especially palladium nanoparticles (Pd NPs), which are characterized by fast reaction rate, high turnover frequency, good selectivity, and high yield. However, the aggregation and precipitation of the metals lead to the decomposition of the catalyst, which results in a significant reduction of the catalytic activity. Therefore, the preparation of homogeneous stabilized palladium nanoparticles catalysts has been widely studied. Stabilized palladium nanoparticles mainly use synthetic polymers. Cellulose microspheres, as a natural polymer material with low-cost and porous fiber network structure, are excellent carriers for stabilizing metal nanoparticles. Cellulose microspheres impregnated with palladium metal nanoparticles were carbonized to have a larger specific surface area and highly dispersed palladium nanoparticles, which exhibited excellent catalytic activity in the catalytic reduction of p-nitrophenol. In this work, the cellulose carbon-based microspheres palladium (Pd@CCM) catalysts were designed and characterized by SEM, TEM, EDS, XRD, FTIR, XPS, TGA, BET, and so on. Furthermore, the catalytic performance of Pd@CCM catalysts was investigated via p-nitrophenol reduction, which showed high catalytic activity. This catalyst also exhibited excellent catalytic performance in the Suzuki-Miyaura coupling reaction. Linking aromatic monomer and benzene through Suzuki-Miyaura coupling was presented as an effective route to obtaining biaryls, and the synthesis method is low-cost and simple. In addition, Pd@CCM showed desirable recyclability while maintaining its catalytic activity even after five recycles. This work is highly suggestive of the design and application of the heterogeneous catalyst.

Hydrogen‐Bond‐Enhanced Photoreforming of Biomass Furans over a Urea‐Incorporated Cu(II) Porphyrin Framework

Solar‐driven upgrading of biomass‐derived 5‐hydroxylmethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA) holds great promise for sustainable production of bio‐plastics and resins. However, the process is limited by poor selectivity and sluggish kinetics due to the vertical coordination of HMF at relatively strong metal sites. Here, we purposely developed a Cu(II) porphyrin framework featuring side‐chain incorporated urea linkages, denoted as TBUPP‐Cu MOF, to render HMF a weak hydrogen bond at the urea site and flat adsorption via π–π stacking with the benzyl moiety. The unique configuration promotes the approaching of –CHO of HMF to the photoexcited porphyrin ring towards kinetically and thermodynamically favourable intermediate formation and subsequent desorption. The charge localization and orbital energy alignment enable the selective activation of O2 over the porphyrin to generate ·O2− and 1O2 instead of highly oxidative H2O2 and ·OH via spin‐flip electron transfer, which drive the ambient oxidation of proximal –CHO. The effective utilisation of redox species and circumvented over‐oxidation facilitate a FDCA selectivity of >90% with a high turnover number of 193 molHMF molCu−1. The facile purification of high‐purity FDCA and zero‐waste recycling of intermediates and durable catalyst feature TBUPP‐Cu MOF a promising photo‐oxidation platform towards net‐zero biorefining and organic transformations.

Hydrogen-Bond-Enhanced Photoreforming of Biomass Furans over aUrea-Incorporated Cu(II) Porphyrin Framework.

Solar-driven upgrading of biomass-derived 5-hydroxylmethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) holds great promise for sustainable production of bio-plastics and resins. However, the process is limited by poor selectivity and sluggish kinetics due to the vertical coordination of HMF at relatively strong metal sites. Here, we purposely developed a Cu(II) porphyrin framework featuring side-chain incorporated urea linkages, denoted as TBUPP-Cu MOF, to render HMF a weak hydrogen bond at the urea site and flat adsorption via π-π stacking with the benzyl moiety. The unique configuration promotes the approaching of -CHO of HMF to the photoexcited porphyrin ring towards kinetically and thermodynamically favourable intermediate formation and subsequent desorption. The charge localization and orbital energy alignment enable the selective activation of O2 over the porphyrin to generate ·O2- and 1O2 instead of highly oxidative H2O2 and ·OH via spin-flip electron transfer, which drive the ambient oxidation of proximal -CHO. The effective utilisation of redox species and circumvented over-oxidation facilitate a FDCA selectivity of >90% with a high turnover number of 193 molHMF molCu-1. The facile purification of high-purity FDCA and zero-waste recycling of intermediates and durable catalyst feature TBUPP-Cu MOF a promising photo-oxidation platform towards net-zero biorefining and organic transformations.

Plasma-assisted manipulation of vanadia nanoclusters for efficient selective catalytic reduction of NOx

Supported nanoclusters (SNCs) with distinct geometric and electronic structures have garnered significant attention in the field of heterogeneous catalysis. However, their directed synthesis remains a challenge due to limited efficient approaches. This study presents a plasma-assisted treatment strategy to achieve supported metal oxide nanoclusters from a rapid transformation of monomeric dispersed metal oxides. As a case study, oligomeric vanadia-dominated surface sites were derived from the classic supported V2O5-WO3/TiO2 (VWT) catalyst and showed nearly an order of magnitude increase in turnover frequency (TOF) value via an H2-plasma treatment for selective catalytic reduction of NO with NH3. Such oligomeric surface VOx sites were not only successfully observed and firstly distinguished from WOx and TiO2 by advanced electron microscopy, but also facilitated the generation of surface amide and nitrates intermediates that enable barrier-less steps in the SCR reaction as observed by modulation excitation spectroscopy technologies and predicted DFT calculations.

Ameliorating the electronic environment of NiCoP by halogen doping: A strategy for boosting hydrogen evolution performance

The design of highly efficient and robust non-noble metal water splitting catalysts for hydrogen production is crucial to reduce overpotential and energy consumption. Herein, a strategy for in-situ growth of halogen-doped NiCoP (X-NiCoP/NF, X = F, Cl, and Br) catalysts with special morphology on nickel foam is proposed. Both the experimental results and theoretical calculations reveal that the downshift of the d-band center energy can regulate the charge distribution of NiCoP owing to doping of strong electronegativity halogen, thus optimizing the Gibbs free energy of H* absorption (△GH*). The F-NiCoP/NF catalyst achieves remarkable HER activity under alkaline conditions, with overpotential at 10 mA cm−2 (η10) of 59 mV and Tafel slope of 48.9 mV dec−1 in 1.0 M KOH. Moreover, F-doping significantly increases the electrochemically active surface area (ECSA) and turnover frequency (TOF), suggestive of the F promotes the formation of highly dispersed high intrinsic active sites. The F-NiCoP/NF exhibits excellent stability with a negligible decrease in activity after durability tests. This work sheds light on the facile synthesis of highly active and stable catalysts with strong electronegative atom doping for HER.

Heterobimetallic praseodymium-nickel active sites with Pr-N4C2 and Ni-N4 moieties enabling synergistic catalysis of CO2 electroreduction

Lanthanide metals have attracted particular interest in the catalysis of electrochemical CO2 reduction. The synthesis and precise spatial distribution of active sites are fundamental important but still formidably challenging owing to the strong oxygen affinity of lanthanide. Here, heteronuclear Pr1-Ni1 single atoms are supported on the carbon matrix containing surface framework defects from lanthanide contraction. The Pr/Ni-NC catalyst exhibits a CO Faradaic efficiency of 99.1 % with a commercial-scale current density of 237 mA cm−2 and a turnover frequency as high as 18,038 h−1 at −1.1 V due to d-f coupling effect and electronic structure perturbation of Pr. Furthermore, mechanistic investigations unveil that the diatomic active sites effectively reduce the energy barrier of the crucial *COOH formation, in which the Pr site facilitates CO2 activation and the Ni site enables H2O dissociation to accelerate the proton transfer process, thereby ensuring the synergy of catalytic sites to greatly facilitate CO2-to-CO conversion.