Dual Atom Research Articles

Heteronuclear Dual Metal Atom Electrocatalysts for Water-Splitting Reactions.

Hydrogen is considered a promising substitute for traditional fossil fuels because of its widespread sources, high calorific value of combustion, and zero carbon emissions. Electrocatalytic water-splitting to produce hydrogen is also deemed to be an ideal approach; however, it is a challenge to make highly efficient and low-cost electrocatalysts. Single-atom catalysts (SACs) are considered the most promising candidate to replace traditional noble metal catalysts. Compared with SACs, dual-atom catalysts (DACs) are capable of greater attraction, including higher metal loading, more versatile active sites, and excellent catalytic activity. In this review, several general synthetic strategies and structural characterization methods of DACs are introduced, and recent experimental advances in water-splitting reactions are discussed. The authors hope that this review provides insights and inspiration to researchers regarding DACs in electrocatalytic water-splitting.

Engineering Nanozymes for Tumor Therapy via Ferroptosis Self-Amplification.

Ferroptosis induction is an emerging strategy for tumor therapy. Reactive oxygen species (ROS) can induce ferroptosis but are easily consumed by overexpressed glutathione (GSH) in tumor cells. Therefore, achieving a large amount of ROS production in tumor cells without being consumed is key to efficiently inducing ferroptosis. In this study, a self-amplifying ferroptosis-inducing therapeutic agent, Pd@CeO2-Fe-Co-WZB117-DSPE-PEG-FA (PCDWD), is designed for tumor therapy. PCDWD exhibits excellent multi-enzyme activities due to the loading of Fe-Co dual atoms with abundant active sites, including peroxidase-like enzymes, catalase-like enzymes, and glutathione oxidases (GSHOx), which undergo catalytic reactions in the tumor microenvironment to produce ROS, thereby inducing ferroptosis. Furthermore, PCDWD can also deplete GSH in tumor cells, thus reducing the consumption of ROS by GSH and inhibiting the expression of GSH peroxidase 4. Moreover, the photothermal effect of PCDWD can not only directly kill tumor cells but also further enhance its own enzyme activities, consequently promoting ferroptosis in tumor cells. In addition, WZB117 can reduce the expression of heat shock protein 90 by inhibiting glucose transport, thereby reducing the thermal resistance of tumor cells and further improving the therapeutic effect. Finally, X-ray computed tomography imaging of PCDWD guides it to achieve efficient tumor therapy.

Overcoming Fe0/Cr(VI) redox-induced low electron transfer efficiency under neutral pH by iron-based dual active sites-mediated hydrogen atom activation

Efficiently removing hexavalent chromium (Cr(VI)) using iron-based adsorbents under neutral pH conditions continues to pose a challenge. In this study, we constructed nano zero-valent iron (nZVI) supported by carboxylated multi-walled carbon nanotubes (OCNT) composites with iron-based dual active sites through the nitrilotriacetic acid modification (FOC-NA). The acid dissolution experiment, high-resolution transmission electron microscopy (HRTEM), thermogravimetric analyzer (TGA), X-ray photoelectron spectroscopy (XPS), and Raman analysis proved these active sites consisted of iron-carboxylate complex (−COOFe(II)) and OCNT-confined nZVI (Fe0-in-OCNT). The existence of iron-based dual active sites enhanced electron transfer efficiency in Cr(VI) removal under neutral pH conditions. This leaded to a superior adsorption capacity for Cr(VI), as evidenced by a maximum adsorption capacity of 141.29 mg·g−1 at a pH of 6.5. Meanwhile, the formation of a Cr-containing product (−COOFe-O-Cr) on the surface of FOC-NA substantially hindered the re-release of chromium into the environment. Furthermore, this study proposed the significant involvement of active hydrogen atoms (H*) in the reduction of Cr(VI), as confirmed by quenching experiments and analyses using electron spin resonance (EPR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The formation pathway and energy barrier of H* and the −COOFe-O-Cr complex were analyzed by density functional theory (DFT) calculations. This study provided insights for the rational design of iron-based adsorbents with dual active sites to facilitate the activation of H* for Cr(VI) reduction under neutral pH conditions.

Complete Photooxidation of Formaldehyde to CO2 via Ni-Dual-Atom Decorated Crystalline Triazine Frameworks: A DFT Study.

Formaldehyde (CH2O) emerges as a significant air pollutant, necessitating effective strategies for its oxidation to mitigate adverse impacts on human health and the environment. Among various technologies, the photooxidation of CH2O stands out owing to its affordability, safety, and effectiveness. Nitrogen-rich crystalline triazine-based organic frameworks (CTFs) exhibit considerable potential in this domain. Nevertheless, the weak and unstable CH2O adsorption hinders the overall oxidation efficiency of CTF. To address this limitation, we incorporate single and dual Ni atoms into nitrogen-rich CTFs by density functional theory (DFT) calculations, resulting in CTF-Ni and CTF-2Ni. This strategic modification significantly enhances the adsorption capability of CH2O. Notably, this synergy between Ni dual atoms activates CH2O by strong chemical adsorption, thereby reducing the energy barrier of CH2O oxidation and achieving the complete oxidation of CH2O to CO2. Moreover, the introduction of dual-atom Ni over CTF ameliorates visible and near-infrared light absorption and facilitates photoexcited charge transfer and separation. Finally, the underlying mechanisms of complete CH2O oxidation over CTF-2Ni are proposed. This work offers novel insights into the rational design of photocatalysts for CH2O oxidation through the integration of Ni dual atoms into CTFs.

Coordination engineering and electronic structure modulation of FeNi dual-single-atoms encapsulated in N, P-codoped 3D hierarchically porous carbon electrocatalyst for synergistically boosting oxygen reduction reaction

With the increasing energy and environmental issues in recent years, it is vital to explore inexpensive and highly activated oxidation reduction reaction (ORR) catalysts for next generation energy storage and conversion devices such as zinc-air batteries. Herein, FeNi dual-single-atoms were efficiently encapsulated into N,P-codoped 3D hierarchically porous carbon (FeNi DSAs/N,P-PC) by a simple one-step pyrolysis. The resulting FeNi DSAs/N,P-PC catalyst exhibited the better ORR activity with the positive onset potential (Eonset = 1.02 V) and half-wave potential (E1/2 = 0.88 V) over commercial Pt/C, and performed well in the assembled zinc-air batteries (peak power density of 124.73 mW cm−2,and long-term charge/discharge stable cycling for 330 h). The XAFS analysis clearly displayed the coordination structure and interactions of the FeNi dual atoms. The DFT calculations show that P-O bonds have great influence on the electronic structure of the FeNi dual atoms. And Ni site can effectively modulate the electronic structure of the Fe site to promote charge transfer and further reduce the energy barrier of the rate-limiting step. This strategy provides a viable strategy for development of low-cost high-performance transition metal diatomic catalysts suitable for energy conversion and storage devices.

Screening of transition metal dual-atom catalysts for hydrogen evolution reaction based on high-throughput calculation and searching surrogate prediction model using simple features

Dual-atom catalysts for hydrogen evolution reaction have received widespread attention, but precise screening and prediction of high-performance catalysts through simple methods remains a challenge. In this study, we perform high-throughput density functional theory (DFT) calculation and machine learning (ML) to screen and predict the transition metal dual-atom catalysts with N-doped graphene support (TMDACs) for acidic hydrogen evolution reaction (HER). The Fe_Zn and V_Fe DACs were proposed to be the most promising candidates for Pt-based catalyst toward acidic HER from 406 TMDACs, based on the characteristics of HER activity, formation, thermodynamic stability, abundance, environmental friendliness. The Fe_Zn and V_Fe DACs with excellent HER performance is due to the synergistic effect deriving from the interaction between H and dual metal atoms in TMDACs. By determining 6 different ML models with four kind of input features, we find the artificial neural networks (ANN) model can predict the HER performance of TMDACs most accurately only using simple input features, including one-hot-encoding of atomic number and Gibbs free energies of transition metal single-atom catalysts. This work not only proposed the potential TMDACs with high HER performance, but also verified that the ANN model can accurately predict the HER activity of diatomic catalysts with simple input features.

Growth of copper-nickel (Cu-Ni) dual atom catalysts over graphene variants as active anodes for clean oxygen generation: Integrative experimental and computational validation

The development of atomically precise metals on the surface of graphene has led to superior electrocatalytic properties for the clean oxygen production. In this study, Cu single-atom and NiCu dual-atom catalysts supported on different graphene variants were effectively developed as electrocatalysts for the production of clean oxygen. Various techniques, including XRD, SEM, Raman, HR-TEM, EXAFS and XPS, were used to characterize these synthesized electrocatalysts. The extent of reduction in graphene oxide (GO) support was confirmed using Raman analysis which demonstrated a greater ID/IG-apparent intensity ratio, indicating that the GO (ID/IG=0.9) has more sp3-hybridized carbon with respect to the rGO (ID/IG= 0.6). The HR-TEM analysis with EDX and STEM data confirmed the dispersion of Cu and NiCu dimer over the surface of graphene variants. XPS and EXAFS studies revealed predominant metallic nature of Cu and NiCu dimer with the synergistic interplay between the constituent atoms. Copper-nickel dimer catalyst supported on reduced graphene oxide (CuNi/rGO) demonstrated the best electrocatalytic performance, where a lower overpotential of 320 mV was observed to reach a current density of 10 mA cm−2 with lowest Tafel slope of 110 mV/dec for oxygen evolution reaction. Good stability was observed after 1000 CV cycles and 50 h of electrolysis in 1.0 M KOH electrolytic solution at an oxidation potential of 1.62 V (vs RHE). Control experiments were also performed using borosilicate pyrex glass and Teflon made electrochemical cells in order to over rule the probable involvement of leached out impurities in OER reaction under extreme alkaline conditions. The calculations obtained from Density Functional Theory (DFT) suggest that the dual-atom catalysts have lower overpotential (0.33 V at Cu-site) with respect to the single-atom catalysts, which agreed well with the experimental results. Also, the Cu-site OER was found to have lower overpotential (0.33 V) than the Ni-site (0.47 V). Thus, this study can provide valuable insights into developing low-cost dual-atom electrocatalysts, where the synergism between constituent elements in the dimer and their stabilization by graphene matrix can be exploited for various electrochemical reactions.

Type‐I‐Organic‐Photosensitizer‐Functionalized Upconversion Nanoparticles for Enhanced Photodynamic Therapy

AbstractPhotodynamic therapy (PDT) has achieved great progress in cancer treatment because it generates reactive oxygen species (ROS) in a noninvasive manner. Nonetheless, the majority of light‐sensitive photosensitizers (PSs) are only sensitive to UV or visible light, suffering limitations such as phototoxicity (UV) and low tissue penetration capabilities (UV–visible). What is more, another impact factor, namely the hypoxic environment within a tumor always inhibits the production of ROS for treatment efficacy. To overcome these problems, herein, one new type‐I PS containing selenium (Se6) is designed. Benefiting from the dual heavy atom effects of selenium and bromine, Se6 can produce short‐lived hydroxyl (•OH) and long‐lived superoxide anion (O2•−) under both normoxic and hypoxic conditions, which is superior to commonly used oxygen‐dependent type‐II PSs, such as chlorine e6, zinc phthalocyanine. Combining Se6 and upconversion nanoparticles with the ability to upconvert near‐infrared (NIR) light to UV–visible light can greatly overcome the tissue penetration depth, phototoxicity, and oxygen‐dependent limitation of the PDT process, which demonstrates a significant performance in vivo to achieve better therapy efficiency.

Tackling the activity and selectivity challenges of electrocatalysts towards CO2 reduction reaction via atomically dispersed dual atom catalysts

Atomically dispersed catalysts are widely employed in electrochemical CO2 reduction reaction (CO2RR) owing to maximal atomic utilization and outstanding intrinsic activity. Dual atom catalysts (DACs) can provide dispersed active sites and distinct electronic structure, which is conducive to the catalytic performance. In this work, we explored a series of DACs composed of transition metals or main group metals supported on nitrogen-doped graphene (M2–NC) toward high-performance CO2RR. The radius of metal atom is a key factor determining the stability of M2–NC, that metals (M = Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Sn, Pt, and Bi) with small radius can be steadily anchored. Fe2/Co2/Ru2–NC are screened out to activate CO2 because of the strong interaction between metals d orbitals and CO2 2π orbitals. The results show that Fe2/Co2–NC can promote CO2RR to generate HCOOH with limiting potentials (UL) of −0.36 and −0.25 V. Ru2–NC can catalyze the generation of CH3OH and CH4 with UL of −0.28 V. Limited potential difference between CO2RR and hydrogen evolution reaction (HER) show that Fe2/Co2/Ru2–NC can inhibit HER during CO2RR. This work demonstrates Fe2/Co2/Ru2–NC as high-performance CO2RR catalysts and highlights the type of central metal atoms as a vital role for atomically dispersed electrocatalysts.

Tailoring atomic strain environment for high-performance acidic oxygen reduction by Fe-Ru dual atoms communicative effect

Tailoring atomic strain environment for high-performance acidic oxygen reduction by Fe-Ru dual atoms communicative effect

Synergistic Electronic Interaction of Nitrogen Coordinated Fe-Sn Double-Atom Sites: An Efficient Electrocatalyst for Oxygen Reduction Reaction.

Double-atom site catalysts (DASs) have emerged as a recent trend in the oxygen reduction reaction (ORR), thereby modifying the intermediate adsorption energies and increasing the activity. However, the lack of an efficient dual atom site to improve activity and durability has limited these catalysts from widespread application. Herein, the nitrogen-coordinated iron and tin-based DASs (Fe-Sn-N/C) catalyst are synthesized for ORR. This catalyst has a high activity with ORR half-wave potentials (E1/2) of 0.92V in alkaline, which is higher than those of the state-of-the-art Pt/C (E1/2=0.83V), Fe-N/C (E1/2=0.83V), and Sn-N/C (E1/2=0.77V). Scanning electron transmission microscopy analysis confirmed the atomically distributed Fe and Sn sites on the N-doped carbon network. X-ray absorption spectroscopy analysis revealed the charge transfer between Fe and Sn. Both experimental and theoretical results indicate that the Sn with Fe-NC (Fe-Sn-N/C) induces charge redistribution, weakening the binding strength of oxygenated intermediates and leading to improved ORR activity. This study provides the synergistic effects of DASs catalysts and addresses the impacts of P-block elements on d-block transition metals in ORR.

Synergy of heterogeneous Co/Ni dual atoms enabling selective C–O bond scission of lignin coupling with in-situ N-functionalization

Selective cleavage of Csp2OCH3 bond in lignin without breaking other types of CO bonds followed by N-functionalization is fascinating for on-purpose valorization of biomass. Here, a Co/Ni-based dual-atom catalyst CoNiDA@NC prepared by in-situ evaporation and acid-etching of metal species from tailor-made metal–organic frameworks was efficient for reductive upgrading of various lignin-derived phenols to cyclohexanols (88.5%–99.9% yields), which had ca. 4 times higher reaction rate than the single-atom catalyst and was superior to state-of-the-art heterogeneous catalysts. The synergistic catalysis of Co/Ni dual atoms facilitated both hydrogen dissociation and hydrogenolysis steps, and could optimize adsorption configuration of lignin-derived methoxylated phenols to further favor the Csp2–OCH3 cleavage, as elaborated by theoretical calculations. Notably, the CoNiDA@NC catalyst was highly recyclable, and exhibited excellent demethoxylation performance (77.1% yield) in real lignin monomer mixtures. Via in-situ cascade conversion processes assisted by dual-atom catalysis, various high-value N-containing chemicals, including caprolactams and cyclohexylamines, could be produced from lignin.

Hf and Co Dual Single Atoms Co-Doped Carbon Catalyst Enhance the Oxygen Reduction Performance.

Single-atom metal-doped M-N-C (M═Fe, Co, Mn, or Ni) catalysts exhibit excellent catalytic activity toward oxygen reduction reactions (ORR). However, their performance still has a large gap considering the demand for their practical applications. This study reports a high-performance dual single-atom doped carbon catalyst (HfCo-N-C), which is prepared by pyrolyzing Co and Hf co-doped ZIF-8 . Co and Hf are atomically dispersed in the carbon framework and coordinated with N to form Co-N4 and Hf-N4 active moieties. The synergetic effect between Co-N4 and Hf-N4 significantly enhance the catalytic activity and durability of the catalyst. In an acidic medium, the ORRhalf-wave potential (E1/2) of the catalyst is up to 0.82V , which is much higher than that of the Co-N-C catalyst without Hf co-doping (0.80V). The kinetic current density of the catalyst is up to 2.49Acm-2 at 0.85V , which is 1.74 times that of the Co-N-C catalyst without Hf co-doping. Moreover, the catalyst exhibits excellent cathodic performance in single proton exchange membrane fuel cells and Zn-air batteries. Furthermore, Hf co-doping can effectively suppress the formation of H2O2, resulting in significantly improved stability and durability.

Dual and Triple Atom Electrocatalysts for Energy Conversion (CO2RR, NRR, ORR, OER, and HER): Synthesis, Characterization, and Activity Evaluation

Dual and Triple Atom Electrocatalysts for Energy Conversion (CO₂RR, NRR, ORR, OER, and HER): Synthesis, Characterization, and Activity Evaluation

Influence factors of CO adsorption on C2N-supported dual-atom catalysts unveiled by machine learning and twofold feature engineering.

Dual-atom catalysts (DACs) have emerged as a compelling frontier in the realm of the electrochemical carbon dioxide reduction reaction (CO2RR). However, elucidating the intrinsic properties of dual-atom pairs and their direct correlation with catalytic activity poses significant challenges. Herein, we investigate CO adsorption on 248 kinds of C2N-supported DACs and analyze the underlying structure-activity relationships of dual transition metal (TM) atoms based on density functional theory (DFT) calculations and machine learning (ML) models. Compared to the direct input of atomic features in the decision tree model of ML, we confirm that extra feature engineering with the introduction of the arithmetic combination of atomic features can better reflect the correlation of dual TM atoms on C2N-based DACs. Further feature importance analysis reveals a strong relationship between the last one occupied orbital radius (rv), group number (G) for dual TM atoms and the CO binding strength, as well as a potential connection with the d band centre (εd). Our work provides deeper insights into the design of DACs and highlights the significance of twofold feature engineering for the synergistic effects between dual TM atoms.

Dual Pt atoms stabilized by an optimized coordination environment for propane dehydrogenation

Tailoring atomically dispersed catalysts by various methods has been the subject of intense current research in heterogeneous catalysis. In this work, the structural stability and propane dehydrogenation performance of Pt-TiO2 catalysts with single, dual, and triple Pt atoms doped on the reduced TiO2 surface have been examined. Experimental results indicate the atomically dispersed Pt is thermally very stable and shows exceptionally high activity (TOFpropane = 4.93 s−1) and selectivity (∼98.5 %) for the dehydrogenation reaction. The recently developed machine-learning-based SSW-NN method is then employed to explore the global potential energy surface of the atomically dispersed Pt atom-doped TiO2, which suggests that the single and dual Pt atoms can be tightly held by the vacancies created on the reduced transition-metal oxide, as confirmed by DFT + U calculated energetics. After that, advanced characterization techniques are used in conjunction with microkinetic analysis to establish the quantitative structure–activity relationships. It is found that the dual-Pt-atom structure with two Pt atoms embedded in adjacent Ti and O vacancies is the only active ensemble that dramatically promotes the CH bond activation and hydrogen recombination, as compared to single Pt atoms accommodated by either Ti or O vacancies. These results provide new and direct evidence in support of the idea that specific function can be imparted to specific active sites by tuning their coordination environments, which makes it possible to tailor the catalytic properties of metal oxides to a particular reaction such as propane dehydrogenation.

Discovery of highly efficient dual-atom catalysts for propane dehydrogenation assisted by machine learning.

Propane dehydrogenation (PDH) is a highly efficient approach for industrial production of propylene, and the dual-atom catalysts (DACs) provide new pathways in advancing atomic catalysis for PDH with dual active sites. In this work, we have developed an efficient strategy to identify promising DACs for PDH reaction by combining high-throughput density functional theory (DFT) calculations and the machine-learning (ML) technique. By choosing the γ-Al2O3(100) surface as the substrate to anchor dual metal atoms, 435 kinds of DACs have been considered to evaluate their PDH catalytic activity. Four ML algorithms are employed to predict the PDH activity and determine the relationship between the intrinsic characteristics of DACs and the catalytic activity. The promising catalysts of CuFe, CuCo and CoZn DACs are finally screened out, which are further validated by the whole kinetic reaction calculations, and the highly efficient performance of DACs is attributed to the synergistic effects and interactions between the paired active sites.

Ordered mesoporous carbon with binary CoFe atomic species for highly efficient oxygen reduction electrocatalysis.

The exploration of powerful, efficient and precious metal-free electrocatalysts for facilitating the sluggish kinetics of the oxygen reduction reaction (ORR) is a crucial endeavor in the development and application of energy conversion and storage devices. Herein, we have rationally designed and synthesized bimetallic CoFe species consisting of CoFe nanoparticles and atomically dispersed dual atoms anchored on an ordered mesoporous carbon matrix (CoFe/NC) as highly efficient ORR electrocatalysts. The pyrolyzation temperature for CoFe/NC plays a vital role in regulating the morphology and composition of both the carbon matrix and CoFe species. The optimized CoFe/NC-750 exhibits a favorable ORR performance in 0.1 M KOH with a high half-wave potential (E1/2) of 0.87 V vs. RHE, excellent tolerance to methanol and remarkable durability (no obvious decrease in E1/2 value after 3000 cycles), all of which are superior to the performance of commercial Pt/C. Experimental measurements and density functional theory (DFT) calculations reveal that the improved ORR performance of CoFe/NC-750 is mainly attributed to the electronic structure of atomically dispersed Fe active sites modulated by the surrounding CoFe alloys and Co single atoms, which accelerates the dissociation and reduction of intermediate OH* species and promotes the ORR process.

A synergic investigation of experimental and computational dual atom electrocatalysis for CO2 conversion to C1 and C2+ products

This review delves into the applications of DACs for the eCO2RR, highlighting their pivotal role in producing a range of diverse Cn products. DACs, through their synergistic interactions.

A universal strategy for fabrication of dual atom materials for multifunctional electrocatalysis

A universal strategy for fabrication of dual atom materials for multifunctional electrocatalysis