Catalytic Selectivity Research Articles

Molecularly Imprinted Nanozymes with Substrate Specificity: Current Strategies and Future Direction.

Molecular imprinting technology (MIT) stands out for its exceptional simplicity and customization capabilities and has been widely employed in creating artificial antibodies that can precisely recognize and efficiently capture target molecules. Concurrently, nanozymes have emerged as promising enzyme mimics in the biomedical field, characterized by their remarkable stability, ease of production scalability, robust catalytic activity, and high tunability. Drawing inspiration from natural enzymes, molecularly imprinted nanozymes combine the unique benefits of both MIT and nanozymes, thereby conferring biomimetic catalysts with substrate specificity and catalytic selectivity. In this review, the latest strategies for the fabrication of molecularly imprinted nanozymes, focusing on the use of organic polymers and inorganic nanomaterials are explored. Additionally, cutting-edge techniques for generating atom-layer-imprinted islands with ultra-thin atomic-scale thickness is summarized. Their applications are particularly noteworthy in the fields of catalyst optimization, detection techniques, and therapeutic strategies, where they boost reaction selectivity and efficiency, enable precise identification and quantification of target substances, and enhance therapeutic effectiveness while minimizing adverse effects. Lastly, the prevailing challenges in the field and delineate potential avenues for future progress is encapsulated. This review will foster advancements in artificial enzyme technology and expand its applications.

A Review on Biomass-Derived Carbon Quantum Dots: Emerging Catalysts for Hydrogenation Catalysis.

The circular economy and the depletion of Earth's resources highlight the need to transform waste into value-added emerging materials like carbon quantum dots (CQDs), which show great promise in energy storage, catalysis, and other applications. The production of catalytically active CQDs from biomass garners significant attention due to their unique advantages, such as ease of availability, natural abundance, renewability, low cost, and environmental friendliness. This review addresses the synthesis of CQDs from biomass, the factors influencing their properties and performance, and their diverse applications in catalytic hydrogenation reactions, selective reduction of nitroaromatic compounds, and azo dyes. Recent studies demonstrate that biomass-derived CQDs exhibit significantly improved catalytic activity, selectivity, and stability, effectively addressing the long-standing challenges of low activity and poor stability in catalysts derived from conventional sources.

Gene Cloning, Characterization and Transesterification Reactions of Mgl-C255, a Lipolytic Enzyme from Neobacillus thermocopriae C255 Isolated from Ash from Popocatépetl Volcano

Lipases and carboxylesterases are enzymes of biotechnological interest both for their reactions and their specificity. They have wide-ranging applications in the food, pharmaceuticals, biodiesel synthesis, and bioremediation industries. For that reason, the strain Neobacillus thermocopriae C255 was isolated from ash from Popocatepetl volcano and studied as a new source of lipolytic enzymes. It was identified using 16S ribosomal RNA and flagellar protein FliF sequence homology, yielding 100% identity. From the sequencing of its genome, an enzyme with lipolytic activity, classified as a monoacylglycerol lipase, and named Mgl-C255, was cloned in E. coli BL21, and then expressed, biochemically characterized, and tested via transesterification reactions with alcohols and monosaccharides. Based on its sequence and structure, it was placed within family V, having a catalytic triad of S90-D207-H237. Biochemical characterization showed its highest activity at 40 °C, pH 7.5 to 8.5, with C-2 length substrate preference. No metal ions or inhibitors influenced lipolytic activity, except for PMSF, SDS, Cu−2, and Hg−2. Mgl-C255 retained about 50% of its activity in non-polar solvents and showed synthetic activity in organic solvents, making it a good candidate for studying its catalytic potential and selectivity.

Balancing Activity and Selectivity in Two-electron Oxygen Reduction through First Coordination Shell Engineering in Cobalt Single Atom Catalysts.

The electrochemical two-electron oxygen reduction reaction (2e- ORR) offers a potentially cost-effective and eco-friendly route for the production of hydrogen peroxide (H2O2). However, the competing 4e- ORR that converts oxygen to water limits the selectivity towards hydrogen peroxide. Accordingly, achieving highly selective H2O2 production under low voltage conditions remains challenging. Herein, guided by first-principles density functional theory (DFT) calculations, we show that modulation the first coordination sphere in Co single atom catalysts (Co-N-C catalysts with Co-NxO4-x sites), specifically the replacement of Co-N bonds with Co-O bonds, can weaken the *OOH adsorption strength to boost the selectivity towards H2O2 (albeit with a slight decrease in ORR activity). Further, by synthesizing a series of N-doped carbon-supported catalysts with Co-NxO4-x active sites, we were able to validate the DFT findings and explore the trade-off between catalytic activity and selectivity for 2e- ORR. A catalyst with trans-Co-N2O2 sites exhibited excellent catalytic activity and H2O2 selectivity, affording a H2O2 production rate of 12.86 [[EQUATION]]and an half-cell energy-efficiency of 0.07 [[EQUATION]] during a 100-h H2O2 production test in a flow-cell.

Balancing Activity and Selectivity in Two‐electron Oxygen Reduction through First Coordination Shell Engineering in Cobalt Single Atom Catalysts

The electrochemical two‐electron oxygen reduction reaction (2e‐ ORR) offers a potentially cost‐effective and eco‐friendly route for the production of hydrogen peroxide (H2O2). However, the competing 4e‐ ORR that converts oxygen to water limits the selectivity towards hydrogen peroxide. Accordingly, achieving highly selective H2O2 production under low voltage conditions remains challenging. Herein, guided by first‐principles density functional theory (DFT) calculations, we show that modulation the first coordination sphere in Co single atom catalysts (Co‐N‐C catalysts with Co‐NxO4‐x sites), specifically the replacement of Co‐N bonds with Co‐O bonds, can weaken the *OOH adsorption strength to boost the selectivity towards H2O2 (albeit with a slight decrease in ORR activity). Further, by synthesizing a series of N‐doped carbon‐supported catalysts with Co‐NxO4‐x active sites, we were able to validate the DFT findings and explore the trade‐off between catalytic activity and selectivity for 2e‐ ORR. A catalyst with trans‐Co‐N2O2 sites exhibited excellent catalytic activity and H2O2 selectivity, affording a H2O2 production rate of 12.86 [[EQUATION]]and an half‐cell energy‐efficiency of 0.07 [[EQUATION]] during a 100‐h H2O2 production test in a flow‐cell.

A bioinspired sulfur–Fe–heme nanozyme with selective peroxidase-like activity for enhanced tumor chemotherapy

Iron-based nanozymes, recognized for their biocompatibility and peroxidase-like activities, hold promise as catalysts in tumor therapy. However, their concurrent catalase-like activity undermines therapeutic efficacy by converting hydrogen peroxide in tumor tissues into oxygen, thus diminishing hydroxyl radical production. Addressing this challenge, this study introduces the hemin–cysteine–Fe (HCFe) nanozyme, which exhibits exclusive peroxidase-like activity. Constructed through a supramolecular assembly approach involving Fmoc-l-cysteine, heme, and Fe²⁺ coordination, HCFe distinctly incorporates heme and [Fe–S] within its active center. Sulfur coordination to the central Fe atom of Hemin is crucial in modulating the catalytic preference of the HCFe nanozyme towards peroxidase-like activity. This unique mechanism distinguishes HCFe from other bifunctional iron-based nanozymes, enhancing its catalytic selectivity even beyond that of natural peroxidases. This selective activity allows HCFe to significantly elevate ROS production and exert cytotoxic effects, especially against cisplatin-resistant esophageal squamous cell carcinoma (ESCC) cells and their xenografts in female mice when combined with cisplatin. These findings underscore HCFe’s potential as a crucial component in multimodal cancer therapy, notably in augmenting chemotherapy efficacy.

Synthesis, Characterization and Catalytic/Antimicrobial Activities of Some Transition Metal Complexes Derived from 2-Floro-N-((2-Hydroxyphenyl)Methylene)Benzohydrazide

Background: In the last few decades, the field of coordination chemistry has grown very fast, especially in the fields of pharmaceutical, biological and catalytic studies. In ancient times, metals were thought to be beneficial to health issues but nowadays the link between organic–metal substances and different industrial and medicinal properties is well established. Methods: A Schiff base ligand (2-fluoro-N’-[(E)-2-hydroxyphenyl) methylene] benzohydrazide) was reacted with a series of transition metals to produce complexes with a general formula [ML2(NO3)]NO3.nH2O, where [M = Zn, Cu, Co, Ni, Mn], and [n = 0, 1], corresponding to complexes 1–5. The nature of the bond was determined in the solid state and solution using spectral studies (1H-NMR, 13C-NMR, UV-Vis and FT-IR), TGA, EPR, elemental analysis and molar conductivity measurement. Results: All M(II) complexes are 1:1 electrolytes, as illustrated by their molar conductivities. The results demonstrate that all synthesized complexes present a coordination number of six by the bonding of the bidentate ligand via its azomethine nitrogen atoms and carbonyl oxygen atoms, as well as with one nitrate group as a bidentate ligand via two oxygen atoms. The DPPH radical scavenging technique was used to investigate the antioxidant activities of the ligand [L] and the metal complexes. It is clear that the activity increased in M (II) complexes compared to the Schiff base ligand. Complex 5 showed the highest activity, with an excellent activity of 90.4%, while complex 4 showed the lowest. The antibacterial activities of the Schiff base and its complexes have been examined against various pathogenic bacteria to measure their inhibition potential. Complex 2 showed remarkable activity against Gram (+) bacteria and fungi with an MIC value of 8 μg/mL, which is greater than that of the positive controls, oxytetracycline and fluconazole. The catalytic activities of all complexes were examined in the oxidation of aniline, and the results illustrated that all complexes had a 100% selectivity in producing only azobenzene, and complex 4 had the highest activity (91%). Conclusion: The obtained results from this study show that the antioxidant and antibacterial properties of both the Schiff base ligand and its derived complexes are promising, with some demonstrating remarkable activities. Moreover, the catalytic activities and selectivities of the prepared complexes in aniline oxidation are interesting.

Interplay Between Metal and Acid Sites Tunes the Catalytic Selectivity Over Pd/Nanodiamond Catalysts.

Metal and acid sites are two of the most crucial catalytically active components in heterogeneous catalysis. While variations in the size, morphology, and heterogeneity of metal species, or the manipulation of the strength, location, and density of acid sites, could significantly impact the catalytic performance, the combination and interplay between these sites are even more critical and have been a recent research focus. To achieve highly efficient and selective synergistic catalysis, it is desired to design a catalyst capable of orchestrating the sequential transformation of all reactants and intermediates at different active sites. In this study, we demonstrate that both acid and metal (Pd) sites can be introduced onto a nanodiamond@graphene (NDG) support particle through simple air oxidation and metal salt deposition-precipitation methods, respectively. The presence and assembly of these two catalytically active sites significantly alter the reaction network for the cyclohexanol conversion reaction. Under this strategy, the selectivity toward designated products─cyclohexene, phenol, and benzene─can be precisely tuned by the presence and patterning of these two sites on the nanodiamond particles. Specifically, we show that the catalyst with both acid sites and Pd ensemble sites, i.e., Pd/NDG, can efficiently convert cyclohexanol through consecutive dehydration and dehydrogenation reactions to form benzene with high selectivity (>80%). These findings underscore the potential of integrating metal and acid sites to design advanced catalysts with tailored reactivity and selectivity, paving the way for more efficient and versatile catalytic processes in industrial applications.

Atomic-Scale Tailoring C-N Coupling Sites for Efficient Acetamide Electrosynthesis over Cu-Anchored Boron Nitride Nanosheets.

Electrochemical conversion of carbon and nitrogen sources into valuable chemicals provides a promising strategy for mitigating CO2 emissions and tackling pollutants. However, efficiently scaling up C-N products beyond basic compounds like urea remains a significant challenge. Herein, we upgrade the C-N coupling for acetamide synthesis through coreducing CO and nitrate (NO3-) on atomic-scale Cu dispersed on boron nitride (Cu/BN) nanosheets. The specific form of Cu, such as single atom, nanocluster, and nanoparticles, endows Cu/BN different adsorption capacity for CO and NO3-, thereby dictating the catalytic activity and selectivity for acetamide formation. The Cu nanocluster-anchored BN (Cu NCs/BN) catalyst achieves an industrial-level current density of 178 mA cm-2 for the C-N coupling reaction and an average acetamide yield rate of 137.0 mmol h-1 gcat.-1 at -1.6 V versus the reversible hydrogen electrode. Experimental and theoretical analyses uncover the pivotal role of the strong electronic interaction between Cu nanoclusters and BN, which activates CO and NO3-, facilitates the formation of key *CCO and *NH2 intermediates, and expedites the C-N coupling pathway to acetamide. This work propels the development of atomic structure catalysts for the efficient conversion of small molecules to high-value chemicals through electrochemical processes.

Pt Nanocatalysts Modified with Carbon Dots as Non‐metallic Promoters for Enhanced Selective Hydrogenation Performance

Constructing non‐metal promoter‐decorated Pt‐based catalysts is a promising strategy for enhancing selective hydrogenation performance. Herein, a set of carbon dots (CDs)‐modified Pt/SBA‐15 nanocatalysts were synthesized using atomic layer deposition (ALD) and impregnation techniques. The catalysts were characterized using various techniques, including TEM, ICP‐MS, N2 adsorption‐desorption isotherms, XRD, XPS, H2‐TPD, H‐D exchange, CO‐DRIFTS, etc. The catalytic performance of the CDs‐Pt/SBA‐15 catalysts was evaluated by the selective hydrogenation reaction of cinnamaldehyde (CAL) to cinnamyl alcohol (COL). The results indicate that there is electron transfer between the CDs and Pt, and the addition of CDs can improve the hydrogen spillover effect, both of which significantly influence the selective catalytic hydrogenation performance of the CDs‐Pt/SBA‐15 catalysts. Among the tested catalysts, 0.44CDs‐Pt/SBA‐15 demonstrated the highest catalytic performance, with conversion and selectivity 2.8 times and 2.2 times higher, respectively, than Pt/SBA‐15. This study provides a new perspective on designing and preparing highly efficient non‐metallic promoter‐modified Pt‐based nanocatalysts and has significant implications for their application in catalytic reactions.

Activation of ammonium oxalate on dandelion-derived nitrogen-doped carbon for electrocatalytic oxygen reduction reaction

Development of electrocatalysts with high catalytic activity for the oxygen reduction reaction (ORR) plays an important role in sustainable energy technology. Herein, a carbon-based electrocatalyst was prepared by pyrolyzing the dandelion straw, accompanied with the activation of ammonium oxalate (AO) for the first time. Based on the physical characterization, the DAO-1100 exhibits a well-developed pore structure, rich morphologies, high surface area, high graphitization degree, as well as high total content of pyridinic nitrogen and graphitic nitrogen. Therefore, DAO-1100 shows excellent electrocatalytic activity for ORR at the onset potential of 0.991 V, half-wave potential of 0.883 V and limiting diffusion current of 5.30 mA·cm−2 approximately, in comparison to those of the Pt/C catalyst. DAO-1100 catalyzes the ORR through a 4 e- pathway like Pt/C catalyst. In addition, it also possesses the better operational durability and catalytic selectivity than those of Pt/C catalyst. Therefore, ammonium oxalate, serving as a low-cost, efficient activator, can efficiently promote the transformation of abundant dandelion straw to metal-free biochar catalysts.

Electrocatalytic N2 Reduction Driven by Mo-Based Double-Atom Catalysts Anchored on Graphdiyne

An electrocatalytic nitrogen reduction reaction (eNRR) presents an appealing strategy for ammonia (NH3) production at ambient conditions. Through systematic density functional theory (DFT) calculations, the eNRR performance of 23 double-atom catalysts has been investigated. These catalysts are composed of a Mo atom and a transition metal atom anchored on the graphdiyne (GDY), and they are named MoM-GDYs. Among the 23 MoM-GDYs studied, 14 MoM-GDYs highlighted catalytic selectivity by inhibiting a competitive hydrogen evolution reaction (HER) and demonstrated commendable eNRR catalytic performance. MoRu-GDY, MoMo-GDY, MoFe-GDY and MoY-GDY exhibited excellent eNRR catalytic activity with limiting potentials of −0.05 V, −0.13 V, −0.21 V and −0.24 V, respectively. These 14 catalysts favor N2 adsorption compared to H and exhibit less negative UL than the −0.98 V benchmark of the stepped Ru(0001) surface. Among them, MoRu-GDY has the best catalytic activity with an UL of −0.05 V. The excellent catalytic performance originates from the synergistic effect of the dual catalytic sites, where the alternation of the consecutive and enzymatic paths effectively reduces the limiting potentials. In addition, the catalytic activity can be evaluated using ΔG*NH3 − ΔG*NH2 as a theoretical descriptor, while UL and the ΔG*NH3 − ΔG*NH2 fit coefficient R2 reached 0.99. These findings not only contribute to the development of dual-atom electrocatalysts for eNRR but also offer a valuable pathway for identifying new eNRR catalysts with high activity and selectivity.

Optimizing n-heptane isomerization: The role of copper in enhancing the catalytic activity and selectivity of Pt and Cu-Pt/montmorillonite K10 catalysts

The development of efficient catalysts for n-heptane isomerization is essential for enhancing gasoline octane numbers. In this study, Pt and Cu-Pt/Montmorillonite K10 (MMT) catalysts were prepared and evaluated to investigate the effect of copper on catalytic performance and selectivity in the isomerization of n-heptane. Comprehensive characterization techniques, including XRD, BET, FTIR, TEM, and TPR, were used to investigate the structural, chemical, and electronic properties of the catalysts. Catalytic performance was tested in a fixed-bed reactor over a temperature range of 200 °C to 450 °C, with a liquid hourly space velocity (LHSV) of 1 h−1 and an H2/n-heptane ratio of 20 mL−1. The Pt/MMT catalyst exhibited an isomerization yield of 23.5 % and a selectivity of 66.8 % at 350 °C. In contrast, the incorporation of Cu into the Pt catalyst (0.8Cu-0.1Pt/MMT) enhanced its electronic environment, resulting in a higher isomerization yield of 29.6 % and selectivity of 77.5 % at the same temperature. Additionally, the Cu-Pt/MMT catalyst demonstrated robust long-term stability, maintaining an isomer yield of approximately 28.1 % and selectivity of 75.3 % after 50 h of continuous operation at 350 °C. This study highlights the improved performance of the Cu-Pt/MMT catalyst and offers valuable insights for optimizing bimetallic catalysts in hydrocarbon isomerization applications.

Two-Dimensional Bi2Se3 Nanosheets Synthesis for Efficient Electrocatalytic Production of Ammonia from Nitrate

Ammonia (NH3), a critical component for various industries, is produced through the Haber-Bosch process, which, despite its importance, is a significant source of carbon emissions and operates on a centralized model, emphasizing the need for innovative solutions to decarbonize and decentralize its production. Electrochemical nitrate (NO3–) reduction to NH3 presents a promising alternative to the Haber-Bosch process for NH3 synthesis, with the added advantage of transforming waste into a valuable resource while mitigating water pollution concerns. However, achieving a well-defined active center and catalytic selectivity in the electrochemically driven reaction remains a significant challenge. In this study, we successfully fabricated a highly selective and active 2D Bi2Se3 catalyst, which demonstrated better performance in reducing NO3– to NH3 with a Faradaic efficiency (FE) of approximately 80% (−0.3V (RHE)) and a significant yield rate of 45mgh−1mgcat−1 (0.46 mmolh−1cm−2). Furthermore, the fabricated material exhibited exceptional stability and durability, maintaining a high NO3– reduction of 80% FE even after 10 consecutive cycles of extended use and continuous operation, demonstrating its remarkable resilience and reliability. Our findings show that the prepared catalyst selectively promotes the electrochemical reduction of NO3– to NH3 while suppressing the competing hydrogen evolution reaction (HER). The charge density profile indicates a pronounced charge localization around the Se atoms, implying that the Se active sites in the 2D Bi2Se3 catalyst act as the active center for the NO3– reduction mechanism, playing a crucial role in facilitating the reaction kinetics.

Role of “post-coordination interaction” boosted performance of rare-earth based MOFs derived catalyst for hydrogenation-alkylation cascade reaction

Post-coordination interactions (abbreviated as PCI) play an essential role in the synthesis and optimization of catalysts by influencing their coordination environment, stabilizing reaction intermediates, tuning activity, and allowing for dynamic behavior. In this work, a LaOCl incorporated into carbon-nitrogen supported metallic Co and CoFe alloy catalyst (termed as CF/L-CN-PCI) via PCI strategy has been synthesized. This catalyst was then utilized in a cascade reaction involving nitroarenes and benzyl alcohol. The developed CF/L-CN-PCI catalyst exhibits higher catalytic selectivity compared to CF/L-CN-IWI catalyst prepared by IWI method in cascade reactions. Additionally, this catalyst offers ease of separation and demonstrates good catalytic cycle stability. Various characterization techniques and control experiments were employed to validate the reasons for the enhanced catalytic performance and to investigate the key issues such as the rate-determining step during the reaction process. We hope that this catalyst preparation method can serve as a reference for the development of other superior catalysts and their application in different reactions.

Utilization of Three-Dimensional Electron Diffraction for Structure Determination of Extra-Large-Pore Zeolites.

The development of extra-large-pore (ELP) zeolites is crucial for industries of petrochemical catalysis, notably in processes like diesel cracking and hydrocracking of multi-carbon hydrocarbon substrates. The catalytic performance and selectivity of these zeolites depend heavily on their specific porous structures, making precise structure determination highly essential for understanding their properties and functionalities. However, the complex structures of ELP zeolites pose significant challenges for characterization. Three-dimensional electron diffraction (3DED) has emerged as a leading technique for studying zeolites as it does not require large crystals or pure samples. This review provides an overview of the development and application of 3DED for elucidating ELP zeolite structures. It begins with a summary of zeolites and their structural determination methods, followed by a detailed discussion of the principles and benefits of 3DED, the ELP zeolites discovered to date, and the specific applications and findings by 3DED. Additionally, the review anticipates that combining 3DED with other advanced techniques will enhance the understanding of ELP zeolites, including aspects like heteroatom doping, host-guest interactions, framework flexibility, and detailed structural characterization. This integration is expected to lead to innovations in the development and application of ELP zeolites.

Assessment of four rhodium(I) complexes bearing SNS ligands for the catalytic reaction of chemical CO2 conversion to obtain cyclic carbonates

SNS pincer type ligands (L1-L4) were metallized with RhCl(PPh3)3, yielding new SNS type Rh(I) complexes. Different techniques, including 31P NMR, UV–Vis, XPS, mass, elemental analysis, molar conductivity, and FT-IR were used to analyze the synthesized compounds. According to the spectral data, the molecular structure of Rh(I) complexes has a four-coordinated square planar geometry around the metal center.The complexes’ lack of conductivity properties demonstrates their non-electrolyte nature in solution. The novel SNS-type Rh(I) complexes efficiently catalyzed the coupling of a variety of epoxides and CO2 to create cyclic carbonates in the presence of DMAP as a Lewis base. Diverse cyclic carbonates were also synthesized under ideal conditions with good to perfect yields (2 h, 1.6 MPa, and 100 °C). Following the discovery of new SNS-type Rh(I) catalysts with outstanding catalytic performance, epoxide, the impact of the reaction time, base, CO2 pressure, and temperature was examined for these catalysts. The complex L3-Rh and DMAP displayed the highest catalytic activity (89.6 %) and selectivity (99.4 %) for the coupling of CO2 and ECH under optimum conditions (100 °C, 2 h, and 1.6 MPa).

Oxy-CO2 reforming of methane on Al2O3, MgAl2O4, CeO2 and ZrO2 supported Ni catalysts prepared by deposition-precipitation method

15 (wt%) Ni loaded on Al2O3, MgAl2O4, CeO2 and ZrO2 were synthesized by the deposition-precipitation method and tested in the oxy-CO2 reforming of methane. It was found that the specific surface area, the type of support and its surface properties are important parameters for the deposition-precipitation method. The results showed that higher metallic Ni concentration and higher surface area increased the catalytic activity and selectivity. The effect of Ni loading amount on Al2O3 was investigated and the catalytic activities were found to be close for 10 (wt%) and 15 (wt%). Among the catalysts tested, 15 (wt%) Ni/Al2O3 catalyst prepared by urea deposition-precipitation method was found to be a good alternative for oxy-CO2 reforming of methane.

Diatomic nitrogen-fixation electrocatalysts supported on graphitic carbon nitride achieve significantly low over potentials

The construction and screening of diatomic catalysts (DAC), as well as the exploration of intrinsic descriptors, are attracting increasing attention. In this work, using graphitic carbon nitride (g-CN) as the substrate, we assembled W, Mo, Cr, Mn, Fe, Co, and Ni atoms into DAC and conducted a systematic exploration of the catalytic capabilities of these systems for nitrogen reduction reaction (NRR) using first-principles calculations. Our research demonstrates that MoMn@g-CN exhibits outstanding catalytic activity and selectivity among the investigated 28 catalysts. The overpotential for NRR on MoMn@g-CN along the enzymatic pathway is merely 0.10 V, which is lower than most of the reported catalysts. By conducting in-depth electronic structure calculations, the catalytic mechanism of the DAC is investigated. N2 adsorption and activation are influenced by the σ-acceptor-π∗-donor mechanism. The enhanced activation of nitrogen molecules is attributed to the synergistic effect of two hetero-diatomic species. Moreover, we have identified an new intrinsic descriptor for NRR related to the electronegativity of the two transition metal atoms. This descriptor correlates with the volcano plot of NRR's limiting potential. Our findings can provide valuable insights for the design and high-throughput screening of DAC.

Spin Regulation of Nickel Single Atom Catalyst via Axial Phosphor‐Coordination Achieves Near Unity CO Selectivity in Electrochemical CO2 Reduction

AbstractThe engineering of the spin state and axial coordination of the metal center of single‐atom catalyst (SAC) represents an effective strategy for regulating the catalytic activity, selectivity, and stability toward electrocatalytic reduction of CO2 (ECO2R). However, rational design and deliberate fabrication of SACs with axial coordination of specified atoms remain challenging. Herein, Ni single atoms with axial coordination of phosphorus (NiP−N4−C) and four planar nitrogen atoms are fabricated, which induces reorientation of the 3d orbitals of the Ni atom and shift of the spin state from low (S = 0) to high (S = 2). The enhanced d−p orbital coupling between the Ni and the adsorbents enhances CO2 activation and reduces energy barrier for formation of *COOH, a key intermediate in the ECO2R to produce CO, enabling the high activity and near unity selectivity of CO in ECO2R in a broad potential range of 600 mV (−0.4–−1.0 V vs reversible hydrogen electrode vs RHE), achieving a turnover frequency of 37.2 s−1 at −1.0 V versus RHE. As a bifunctional cathode electrocatalyst, NiP−N4−C demonstrates a peak power density of 18.5 mW cm−2 and maintains cycling durability over 70 h in rechargeable Zn−CO2 batteries.