Dual Atom Research Articles

Selective Self‐Assembly of Atomically Dispersed Iron and Cobalt Dual Atom Catalyst on Anisotropic Mesoporous Carbon Particles for High Performance Seawater Batteries

AbstractNa‐seawater batteries (SWBs) are environmentally friendly energy storage system that utilizes abundant seawater as an electrolyte alternative to conventional distilled water‐based and organic electrolytes. To achieve high energy efficiency in Na‐SWBs, it is necessary to enhance the activity of bifunctional oxygen electrocatalysts. In this study, an atomically dispersed iron and cobalt dual‐atom nitrogen‐doped lens‐shaped mesoporous carbon (FeCo‐LMC) particles is synthesized as a SWB cathode material using the spinodal decomposition of the polymer blend and selective precursor positioning. The well‐aligned mesoporous structure and synergetic effect of the dual‐atom site realize FeCo‐LMC as a comparable bifunctional oxygen catalyst with the lowest overpotential difference (EOER−EORR) among the other catalysts with natural seawater electrolyte. When applied to the SWB system, the FeCo‐LMC shows a highly improved charge/discharge performance compared to Pt/C and a stable cycling performance for 200 h. Density functional theory calculations reveal the enhanced oxygen catalytic activity of FeCo‐LMC owing to electron delocalization and d‐band center adjustment of FeN4–CoN4 structure.

Unique Oxygen-Bridged Nickel Atomic Pairs Efficiently Boost Electrochemical Reduction of Carbon Dioxide.

Benefiting from the synergism between adjacent bimetallic atoms, in comparison with single atom catalysts, the dual atom catalysts have displayed great potential in electrocatalytic CO2 reduction reaction (CO2RR). However, the further modulation of the electronic structure of dual atom sites to enhance CO2RR performance still remains a challenge. Herein, an atomically dispersed oxygen-bridged Ni2N6O/NC catalyst with unique Ni-O-Ni sites is successfully synthesized through the microwave pyrolysis of the supported mixture containing the dinuclear nickel phthalocyanine and glucose on N-doped carbon nanosheets. Experiments and density functional theory calculation reveal that the Ni-O-Ni sites can adsorb H+ from the KHCO3 electrolyte to in situ-form the unique Ni-OH-Ni sites without Ni─Ni bonding interaction, which effectively lowers the energy barrier towards the formation of *COOH from CO2. As a result, the Ni2N6OH/NC catalyst exhibits a 99.4% of CO Faradaic efficiency with a 32.4 mA·cm-2 of CO partial current density at -0.7V versus RHE in H-cell, much superior to the Ni2N6/NC with a Ni-Ni bonding interaction prepared by a similar procedure to that for Ni2N6O/NC but replacing microwave pyrolysis by a traditional heating process.

Harnessing the Potential of Machine Learning to Optimize the Activity of Cu-Based Dual Atom Catalysts for CO2 Reduction Reaction

Harnessing the Potential of Machine Learning to Optimize the Activity of Cu-Based Dual Atom Catalysts for CO₂ Reduction Reaction

Insights into the cooperative interaction of cage-type graphene-based Fe, Mo dual atom catalysts in nitrogen reduction reaction.

Insights into the cooperative interaction of cage-type graphene-based Fe, Mo dual atom catalysts in nitrogen reduction reaction.

Atomic Printing Strategy Achieves Precise Anchoring of Dual-Copper Atoms on C2N Structure for Efficient CO2 Reduction to Ethylene.

Isolated metal sites catalysts (IMSCs) play crucial role in electrochemical CO2 reduction, with potential industrial applications. However, tunable synthesis strategies for IMSCs are limited. Herein, we present an atomic printing strategy that draws inspiration from the ancient Chinese "movable-type printing technology". Selecting customizable combinations of metal atoms as metal precursors from an extensive binuclear metal library. A series of dual-atom catalysts were prepared by utilizing the edge nitrogen atoms in the C2N cavity as anchoring "pincers" to capture metal atoms. To prove utility, the dual atom catalyst Cu2-C2N is investigated as electrocatalytic CO2RR catalyst. The synergistic interaction of dual Cu atoms promotes C-C coupling and guarantees FEC2+ (90.8 %) and FEC2H4. (71.7 %) at -1.10 V vs RHE. DFT calculations revealed the Cu2 site would be subtly flipped during CO2RR for enhancing *CO adsorption and dimerization. We validate that atomic printing strategies are applicable to wide range of metal combinations, representing a significant advancement in the development of IMSCs.

Diatomic Active Sites Embedded Graphyne as Electrocatalysts for Ammonia Synthesis.

Ammonia (NH3) is a vital chemical compound in industry and agriculture, and the electrochemical nitrogen reduction reaction (eNRR) is considered a promising approach for NH3 synthesis. However, the development of eNRR faces the challenge of high overpotential and low Faradaic efficiency. In this work, graphyne (GY) is anchored by 3d, 4d, and 5d dual transition metal atoms to form diatomic catalysts (DACs) and is roundly investigated as an electrocatalyst for eNRR via density functional theory calculations. Due to the protrusion of anchored metal atoms, the active sites of GY are better exposed compared to other substrates, exhibiting higher activity. Through four-step hierarchical high-throughput screening (ΔG*N2 < 0 eV, ΔG*N2→*N2H < 0.4 eV, ΔG*NH2→*NH3 < 0.4 eV, and ΔG*N2 < ΔG*H), the number of selected catalysts in each step is 325, 240, 145, and 20, respectively. Considering a series of factors, including stability, initial potential, and selectivity, 13 kinds of eligible catalysts are identified. Optimal eNRR paths studies show that the best catalyst Mn2@GY features no onset potential. For the three catalysts (Mn2@GY, Ir2@GY, and RhOs@GY), the onset potentials of the most favorable eNRR pathways are -0.07, -0.12, and -0.17 V, respectively. The excellent catalytic activity can be credited to the effective charge transfer and orbital interaction between the active site and adsorbed N2. Our work demonstrates the significance of DACs for ammonia synthesis and provides a paradigm for the study of DACs even for other important reactions.

A Revised High‐Throughput Screening Model on Oxygen Reduction Reaction Over Dual Atom Catalysts Based on the Axial Pre‐Adsorption and O2 Adsorption

AbstractDual‐atom catalysts (DACs) often exhibit superior electrocatalytic activity, due to their versatile combinations and synergistic effects. However, the neglect of both dynamic axial adsorption of the active site upon working potential and the reactant adsorption as a rate‐determining step hinders the establishment of an accurate high‐throughput screening strategy. Here, the oxygen reduction reaction (ORR) of 42 kinds of 3d–3d metal DACs by density functional theory (DFT) calculations are systematiclly investigated and demonstrated that the ORR kinetics can be limited by O2* adsorption besides the proton–electron transfer step and the active center of DACs may be reconstructed by axial pre‐adsorption of intermediates under working potential. Therefore, the ORR volcano plot is proposed by using both the O2* and OH* adsorption as activity descriptors. Then, a high‐throughput screening method is constructed and 38 promising ORR DACs are screened out from 267 DACs containing 3d, 4d, or 5d metals. Importantly, the previously unexplored MnCoN6 DAC is also experimentally synthesized, and exhibits ultrahigh ORR activity outperforming Pt/C, perfectly matching with theoretical prediction. In short, this work not only proposes a volcano plot‐based high‐throughput screening method but also provides a proof‐of‐concept of experimental verification of theoretical prediction to heuristically design electrocatalysts for other reactions.

Cooperativity in Fe2N5P dual-atomic site: Designing dual atom catalysts for water-splitting reactions

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Single Atom Catalyst for Nitrate-to-Ammonia Electrochemistry.

Various life forms suffer from the negative effects of nitrate when it accumulates in water bodies, which is a major concern in the present day. The removal of nitrate from water bodies is a critical challenge, and the most effective method to achieve that is to change it into ammonia. Ammonia is a clean energy source and a vital input for the fertilizer industry. The Haber-Bosch process, which dominates the industrial production of ammonia, requires a lot of energy. A more sustainable way to produce ammonia is to use nitrate-contaminated water and reduce it to ammonia through electrocatalysis. This review is constituted of amalgamated articles featuring unique conditions that affect the productivity and activity of the transition metal single atom catalyst (TNMSAC) for the electrocatalytic nitrate reduction to ammonia (NRA) reaction. It explores factors such as nitrate ion adsorption, the characteristics of the central electroactive transition metal, the type of coordinating atoms, the impact of potential on stability, and the interplay among single atoms on the selectivity and yield of ammonia gas. In addition, this review also covers advanced concepts such as dual-atom catalysts, dual single atom catalysts, and single atom alloys. The review will provide valuable guidance for enhanced comprehension and strategic designing of TNMSAC for the electrocatalytic conversion of NRA, which will contribute to achieving a green ammonia economy.

Theoretical study of the efficiencies of graphyne supported Mo single-atom catalyst (SAC) and Mo-Ni dual-atom catalyst (DAC) on hydrogen evolution reaction

In this work, by adding one molybdenum atom or two molybdenum and nickel atoms on the surface graphyne support, single atom catalyst (SAC) and dual atoms catalyst (DAC) were designed. The different spin multiplicities for both catalysts were analyzed by the relative energies, adsorption energies and frontier orbitals. The results showed in both case of SACs and DACs, the catalyst with spin multiplicity = 3 is desired. Then, the efficiency of these two catalysts as high-performance and cost-effective catalysts in the HER process was investigated theoretically. All calculations were performed using M06-2X/def2SV level of theory. In the HER mechanism, it has been found that the DAC has higher favorability than the SAC. Both steps (Volmer reaction and Tafel or Heyrovsky reaction) are more exothermic using DAC, and the difference between SAC and DAC is higher in the second step. The effect of solvent on these steps has been studied using water and methanol as two common solvents. The reactions are less exothermic in the solvent; but they are still highly exothermic and thermodynamically favorable. Moreover, despite the gas phase data, in both solvents, the use of DAC gives less favorable data versus the SAC. The data also showed the little preference of water versus the methanol as solvent.

Tuning the Inter‐Metal Interaction between Ni and Fe Atoms in Dual‐Atom Catalysts to Boost CO2 Electroreduction

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

Rare Earth Er‐Nd Dual Single‐Atomic Catalysts for Efficient Visible‐light Induced CO2 Reduction to CnH2n+1OH (n=1, 2)

Efficient synthesis of CnH2n+1OH (n=1, 2) via photochemical CO2 reduction holds promise for achieving carbon neutrality but remains challenging. Here, we present rare‐earth dual single atoms (SAs) catalysts containing ErN6 and NdN6 moieties, fabricated via an atom‐confinement and coordination method. The dual Er‐Nd SAs catalysts exhibit unprecedented generation rates of 1761.4 μmol g–1 h–1 and 987.7 μmol g–1 h–1 for CH3CH2OH and CH3OH, respectively. Through a combination of theoretical calculation, X‐ray absorption near edge structural analysis, aberration‐corrected transmission electron microscopy, and in‐situ FT‐IR spectroscopy, we demonstrate that the Er SAs facilitate charge transfer, serving as active centers for C−C bond formation, while Nd SAs provide the necessary *CO for C−C coupling in C2H5OH synthesis under visible light. Furthermore, the experiment and density functional theory calculation elucidate that the variety of electronic states induced by 4f orbitals of the Er SAs and the p−f orbital hybridization of Er−N moieties enable the formation of charge‐transfer channel. Therefore, this study sheds light on the pivotal role of *CO adsorption in achieving efficient conversion from CO2 to CnH2n+1OH (n=1, 2) via a novel rare‐earth‐based dual SAs photocatalysis approach.

Rare Earth Er-Nd Dual Single-Atomic Catalysts for Efficient Visible-light Induced CO2 Reduction to CnH2n+1OH (n=1, 2).

Efficient synthesis of CnH2n+1OH (n=1, 2) via photochemical CO2 reduction holds promise for achieving carbon neutrality but remains challenging. Here, we present rare earth dual single atoms (SAs) catalysts containing ErN6 and NdN6 moieties, fabricated via an atom-confinement and coordination method. The dual Er-Nd SAs catalysts exhibit unprecedented generation rates of 1761.4 μmol g-1 h-1 and 987.7 μmol g-1 h-1 for CH3CH2OH and CH3OH, respectively. Through a combination of theoretical calculation, XAFS analysis, aberration-corrected HAADF-STEM, and in-situ FTIR spectroscopy, we demonstrate that the Er SAs facilitate charge transfer, serving as active centers for C-C bond formation, while Nd SAs provide the necessary *CO for C-C coupling in C2H5OH synthesis under visible light. Furthermore, the experiment and DFT calculation elucidate that the variety of electronic states induced by 4 f orbitals of the Er SAs and the p-f orbital hybridization of Er-N moieties enable the formation of charge-transfer channel. Therefore, this study sheds light on the pivotal role of *CO adsorption in achieving efficient conversion from CO2 to CnH2n+1OH (n=1, 2) via a novel rare earth-based dual SAs photocatalysis approach.

Coordination Environment and Distance Optimization of Dual Single Atoms on Fluorine‐Doped Carbon Nanotubes for Chlorine Evolution Reaction

AbstractThe chlorine evolution reaction (CER) is a crucial anode reaction in the chlor‐alkali industrial process. Precious metal‐based dimensionally stable anodes (DSA) are commonly used as catalysts for CER but are constrained by their high cost and low selectivity. Herein, a Pt dual singe‐atom catalyst (DSAC) dispersed on fluorine‐doped carbon nanotubes (F‐CNTs) is designed for an efficient and robust CER process. The prepared Pt DSAC demonstrates excellent CER activity with a low overpotential of 21 mV to achieve a current density of 10 mA cm−2 and a remarkable mass activity of 3802.6 A gpt−1 at an overpotential around 30 mV, outperforming those of commercial DSA and Pt single‐atom catalyst. The excellent CER performance of Pt DSAC is attributed to the high atomic utilization and improved intrinsic activity. Notably, introducing fluorine atoms on CNTs increases the oxidation and chlorination resistance of Pt DSAC, and reduces the demetalization ratio of Pt atoms, resulting in excellent long‐term CER stability. Theoretical calculations reveal that several Pt DSAC configurations with optimized first‐shell ligands and interatomic distance display lower energy barriers for Cl intermediates generation and weaker ionic Pt−Cl bond interaction, which are favorable for the CER process.

Precise synthesis of dual atom sites for electrocatalysis

Precise synthesis of dual atom sites for electrocatalysis

Anchoring cobalt dual-atom pairs on open hollow-structured carbon via a facile in-situ synthetic strategy for enhanced advanced oxidation processes

Atomically dispersed catalysts offer unprecedented opportunities for high-efficiency Fenton-like oxidation of organic pollutants in water. However, the hazardous metal leaching of atomically dispersed catalysts hinders their practical application for wastewater treatment, while the inaccessible interior active sites in carbon substrates have been commonly overlooked. Herein, we develop a straightforward approach for tightly anchoring cobalt dual-atom pairs on nitrogen-doped open hollow carbon structure (Co-NOHC) via an in-situ polyelectrolyte nanosphere-guided strategy. The unique open hollow carbon structure benefits the electron/mass transfer and maximizes the exposure of active sites. As a result, the as-synthesized Co-NOHC exhibits outstanding peroxymonosulfate activation activity and Fenton-like performance in oxidation by taking rhodamine B degradation as an example. Remarkably, the turnover frequency of the Co-NOHC is 6.5, 26.5, and 9.3 times higher than that of the Co2+, cobalt, and its oxides, respectively, and its catalytic activity also greatly outperforms the pristine zeolitic-imidazole frameworks derived Co-based atomically dispersed catalysts. More importantly, benefitted from the stable anchoring of cobalt dual atoms, the Co2+ leaching from the Co-NOHC is greatly alleviated, as low as 0.1 mg/L after the catalytic reaction, showing outstanding stability as compared to most atomically dispersed catalysts. Furthermore, the reactive active species, including SO4−, OH and O2− radicals, and electron-transfer mechanism are demonstrated to dominate the rhodamine B removal. This work offers a new consideration for promoting the development of the advanced catalysts and their potential applications in advanced oxidation process.

Tuning the interfacial reaction environment via pH-dependent and induced ions to understand C–N bonds coupling performance in NO3− integrated CO2 reduction to carbon and nitrogen compounds over dual Cu-based N-doped carbon catalyst

Dual atomic catalysts (DAC), particularly copper (Cu2)-based nitrogen (N) doped graphene, show great potential to effectively convert CO2 and nitrate (NO3−) into important industrial chemicals such as ethylene, glycol, acetamide, and urea through an efficient catalytical process that involves C–C and C–N coupling. However, the origin of the coupling activity remained unclear, which substantially hinders the rational design of Cu-based catalysts for the N-integrated CO2 reduction reaction (CO2RR). To address this challenge, this work performed advanced density functional theory calculations incorporating explicit solvation based on a Cu2-based N-doped carbon (Cu2N6C10) catalyst for CO2RR. These calculations are aimed to gain insight into the reaction mechanisms for the synthesis of ethylene, acetamide, and urea via coupling in the interfacial reaction micro-environment. Due to the sluggishness of CO2, the formation of a solvation electric layer by anions (F−, Cl−, Br−, and I−) and cations (Na+, Mg2+, K+, and Ca2+) leads to electron transfer towards the Cu surface. This process significantly accelerates the reduction of CO2. These results reveal that *CO intermediates play a pivotal role in N-integrated CO2RR. Remarkably, the Cu2-based N-doped carbon catalyst examined in this study has demonstrated the most potential for C–N coupling to date. Our findings reveal that through the process of a condensation reaction between *CO and NH2OH for urea synthesis, *NO3− is reduced to *NH3, and *CO2 to *CCO at dual Cu atom sites. This dual-site reduction facilitates the synthesis of acetamide through a nucleophilic reaction between NH3 and the ketene intermediate. Furthermore, we found that the I− and Mg2+ ions, influenced by pH, were highly effective for acetamide and ammonia synthesis, except when F− and Ca2+ were present. Furthermore, the mechanisms of C–N bond formation were investigated via ab-initio molecular dynamics simulations, and we found that adjusting the micro-environment can change the dominant side reaction, shifting from hydrogen production in acidic conditions to water reduction in alkaline ones. This study introduces a novel approach using ion-H2O cages to significantly enhance the efficiency of C–N coupling reactions.

Boron-doping tunes nitrogen species to abundant edge-N and B-N matrix for efficient phosphate removal in capacitive deionization: Additional accessible sites and defective centers

The elimination of eutrophication necessitates the implement of a clean and efficient phosphate removal strategy. Capacitive deionization (CDI) is recently regarded a promising approach for removing pollutants from aqueous environment with high-efficiency, facile operation, and low-energy consumption. Development of electrode materials with good properties is crucial for CDI. In this study, novel edge-N-modified boron-doped hierarchical carbon composites (MBCNs) were prepared via a hard template strategy for phosphate electrosorption. According to the pseudo-second-order kinetic, the MBCN2 electrode exhibited a dynamic capacity of 196.02 mg PO43− g−1 in 150 min with an initial concentration of 100 mg PO43− L−1 at 1.2 V. And it also demonstrated an exceptional saturation capacity of 399.70 mg PO43− g−1 under the Langmuir model. Based on theoretical analysis and experimental results, the incorporation of boron atoms in the carbon framework indicated a dual reinforcement. This included an enhanced proportion of edge-N modifications for defective centers and sufficient high-polarity B-N matrix for additional available active sites. The joint contribution of edge-N and B-N matrix revealed favorable electrical double layer capacitance, which resulted in good phosphate removal performance. This work disclosed the synergistic impact of dual nonmetallic atom doping, providing insights into the efficient phosphate removal anode for CDI.

Accelerating the design of catalysts for CO2 electroreduction to HCOOH: A data-driven DFT-ML screening of dual atom catalysts

Dual-atom catalysts (DACs) have emerged as potential catalysts for effective electroreduction of CO2 due to their high atom utilization efficiency and multiple active sites. However, the screening of DACs remains a challenge due to the large number of possible combinations, making exhaustive experimental or computational screening a daunting task. In this study, a density functional theory (DFT)-based machine learning (ML)-accelerated (DFT-ML) hybrid approach was developed to test a set of 406 dual transition metal catalysts on N-doped graphene (NG) for the electroreduction of CO2 to HCOOH. The results showed that the ML algorithms can successfully capture the relationship between the descriptors of the DACs (inputs) and the limiting potential for HCOOH generation (output). Of the four ML algorithms studied in this work, the feedforward neural network model achieved the highest prediction accuracy (the highest correlation coefficient (R2) of 0.960 and the lowest root mean square error (RMSE) of 0.319 eV on the test set) and the predicted results were verified by DFT calculations with an average absolute error of 0.14 eV. The DFT-ML approach identified Co-Co-NG and Ir-Fe-NG as the most active and stable electrocatalysts for the electrochemical reduction of CO2 to HCOOH. The DFT-ML hybrid approach exhibits exceptional prediction accuracy while enabling a significant reduction in screening time by an impressive 64% compared to conventional DFT-only calculations. These results demonstrate the immense potential of using ML methods to accelerate the screening and rational design of efficient catalysts for various energy and environmental applications.

Insight into mechanism for remarkable photocatalytic hydrogen evolution of Cu/Pr dual atom co-modified TiO2.

The development of high-activity photocatalysts is crucial for the current large-scale development of photocatalytic hydrogen applications. Herein, we have developed a strategy to significantly enhance the hydrogen photocatalytic activity of Cu/Pr di-atom co-modified TiO2 architectures by selectively anchoring Cu single atoms on the oxygen vacancies of the TiO2 surface and replacing a trace of Ti atoms in the bulk with rare earth Pr atoms. Calculation results demonstrated that the synergistic effect between Cu single atoms and Pr atoms regulates the electronic structure of Cu/Pr-TiO2, thus promoting the separation of photogenerated carriers and their directional migration to Cu single atoms for the photocatalytic reaction. Furthermore, the d-band center of Cu/Pr-TiO2, which is located at -4.70 eV, optimizes the adsorption and desorption behavior of H*. Compared to TiO2, Pr-TiO2, and Cu/TiO2, Cu/Pr-TiO2 displays the best H* adsorption Gibbs free energy (-0.047 eV). Furthermore, experimental results confirmed that the photogenerated carrier lifetime of Cu/Pr-TiO2 is not only the longest (2.45 ns), but its hydrogen production rate (34.90 mmol g-1 h-1) also significantly surpasses those of Cu/TiO2 (13.39 mmol g-1 h-1) and Pr-TiO2 (0.89 mmol g-1 h-1). These findings open up a novel atomic perspective for the development of optimal hydrogen activity in dual-atom-modified TiO2 photocatalysts.