Atomic Sites Research Articles

Simultaneously activating molecular oxygen and surface lattice oxygen on Pt/TiO2 for low-temperature CO oxidation

Developing high-performance Pt-based catalysts with low Pt loading is crucial but challenging for CO oxidation at temperatures below 100 °C. Herein, we report a Pt-based catalyst with only a 0.15 wt% Pt loading, which consists of Pt–Ti intermetallic single-atom alloy (ISAA) and Pt nanoparticles (NP) co-supported on a defective TiO2 support, achieving a record high turnover frequency of 11.59 s–1 at 80 °C and complete conversion of CO at 120 °C. This is because the coexistence of Pt–Ti ISAA and Pt NP significantly alleviates the competitive adsorption of CO and O2, enhancing the activation of O2. Furthermore, Pt single atom sites are stabilized by Pt–Ti ISAA, resulting in distortion of the TiO2 lattice within Pt–Ti ISAA. This distortion activates the neighboring surface lattice oxygen, allowing for the simultaneous occurrence of the Mars-van Krevelen and Langmuir–Hinshelwood reaction paths at low temperatures.

Insight into the performance and mechanism of N,O,S-codoped porous carbon based CO single-atom catalysts in organic oxidation through peroxymonosulfate activation

Single-atom catalysts (SACs) are charming for heterogeneous Fenton-like processes due to their unique and adjustable electron structure. Developing novel SACs and elucidating their mechanisms are critical for the development of water purification techniques. Herein, we present an N,O,S-codoped carbon based Co SAC (CoSA-N-CO,S) synthesized by anchoring isolated Co atoms onto porous carbon derived from low-cost protic salt. This catalyst exhibits significant efficiency in activating peroxymonosulfate (PMS) for rapid ibuprofen (IBU) degradation, achieving approximately 98.2 % within 10 min at a concentration of 0.2 g/L catalyst and 2 mM PMS, under ambient pH and at 30 °C, and demonstrates excellent reusability. Intensive studies reveal that the highly active atomic Co sites are favorable for activating PMS to produce both radical (SO4− and OH) and nonradical 1O2, while the electron-rich O and S sites contribute to PMS reduction to generate SO4− and OH. The CoSA-N-CO,S/PMS system leverages the synergy between radical and nonradical oxidation across multiple active sites, resulting in exceptional resistance to interference and high efficiency in degradation and mineralization of diverse organic pollutants. This study develops a novel single-atom catalyst for wastewater treatment and elucidates the mechanism behind PMS activation by a carbon-based cobalt single atom catalyst.

Precision Control of Amphoteric Doping in Cu x Bi2Se3 Nanoplates.

Copper-doped Bi2Se3 (Cu x Bi2Se3) is of considerable interest for tailoring its electronic properties and inducing exotic charge correlations while retaining the unique Dirac surface states. However, the copper dopants in Cu x Bi2Se3 display complex electronic behaviors and may function as either electron donors or acceptors depending on their concentration and atomic sites within the Bi2Se3 crystal lattice. Thus, a precise understanding and control of the doping concentration and sites is of both fundamental and practical significance. Herein, we report a solution-based one-pot synthesis of Cu x Bi2Se3 nanoplates with systematically tunable Cu doping concentrations and doping sites. Our studies reveal a gradual evolution from intercalative sites to substitutional sites with increasing Cu concentrations. The Cu atoms at intercalative sites function as electron donors while those at the substitutional sites function as electron acceptors, producing distinct effects on the electronic properties of the resulting materials. We further show that Cu0.18Bi2Se3 exhibits superconducting behavior, which is not present in Bi2Se3, highlighting the essential role of Cu doping in tailoring exotic quantum properties. This study establishes an efficient methodology for precise synthesis of Cu x Bi2Se3 with tailored doping concentrations, doping sites, and electronic properties.

Ni3S2@MoS2 nano-arrays with Mo atomic site as efficient photoanode materials for photoelectrocatalytic inactivation of antibiotic-resistance bacteria and degradation of antibiotic-resistance gene

Ni3S2@MoS2 nano-arrays with Mo atomic site as efficient photoanode materials for photoelectrocatalytic inactivation of antibiotic-resistance bacteria and degradation of antibiotic-resistance gene

Atomistic insight into the unique mechanism of helium management at FCC{111}//{111}FCC semi-coherent interfaces

Interfaces are effective traps for implanted helium (He), and research on the He interactions with interfaces contributes to our comprehension of the role of interface structure in controlling and mitigating the deleterious effects of He. In this study, we investigate He interactions with three types of face-centered cubic (FCC){111}//{111}FCC semi-coherent interfaces: Cu/Ni, Cu/Pd, and Cu/Ag {111} semi-coherent interfaces. Utilizing molecular dynamics simulations, we demonstrate that He atoms exhibit a tendency to segregate at these semi-coherent interfaces. Notably, the presence of new dislocation loops, accompanied by extrinsic stacking faults, is observed at these semi-coherent interfaces as the concentration of He atoms increases continuously. Moreover, this unique structural evolution of interfaces leads to the dissociation of misfit dislocation intersections, thereby significantly augmenting the nucleation sites for He atoms and improving the He managements at these interfaces. These findings provide insights into the interaction between He atoms and FCC{111}//{111}FCC semi-coherent interfaces, enriching our current understanding of He management at such interfaces.

Enhanced performance of H-C3N2 monolayer as anode material for Li-ion batteries by phosphorus doping

Graphitic carbon nitride sheets (CxNy), which possess a two-dimensional structure similar to N-doped graphene, have been extensively studied as potential anode materials for ion batteries due to their high nitrogen content and porous defect sites that can serve as atomic storage sites for alkali metals. compared with most carbon nitride sheets, monolayer H-C3N2 has the characteristics of higher pyridinic nitrogen content and porosity, and can provide more Li adsorption sites, resulting in a superior theoretical capacity of 2791 mAh/g. However, the high diffusion barrier of 1.75 eV implies the low charge/discharge rate, which limits its application in lithium-ion batteries. Here, this paper demonstrates that doping P atoms in H-C3N2 (PC18N11) has some advantages for application in batteries. Specifically, monolayer PC18N11 exhibits excellent stability and conductivity, much higher theoretical specific capacity (3542 mAh/g). Moreover, PC18N11 exhibits metallic properties when Li-ion is adsorbed, the conductivity is improved, and the interaction between Li-ions will greatly reduce the diffusion barrier. These favorable properties indicate that P-doped H-C3N2 monolayer is a promising anode material for Li-ion batteries.

Research on Residual Gas Adsorption on Surface of Hexagonal Boron Nitride-Based Memristor.

As a promising nonvolatile memory device with two ends, the memristor has received extensive attention for its industrial manufacture. Density functional theory was used to analyze the adsorption properties of residual gas on hexagonal boron nitride (h-BN)-based memristor model surfaces with Stone-Wales-5577 grain boundary defects [h-BN(SW)]. First, by calculating the adsorption energy, geometric parameters, and charge transfer, we identified the most stable adsorption sites for hydrogen atoms (H-TB1) and H2 molecules (H2-TN2). We observed a tendency toward chemisorption for hydrogen atoms and physical adsorption for H2 molecules at these sites. Furthermore, two coadsorption configurations were formed by introducing H2 molecules and hydrogen atoms into single adsorption configurations: namely H-TB1_H2-TN1TN2 and H2-TN2_H-TB1TN1TN3. In the case of hydrogen-based configuration, there is weak dissociation of the H2 molecule, which does not facilitate hydrogen atom adsorption. However, adjacent hydrogen atoms tend to form stable dimers, while excess hydrogen atoms have a tendency to weakly chemisorb in the case of H2-based configuration. The pristine h-BN surface is more favorable for hydrogen atom migration compared to the h-BN(SW) surface due to its higher adsorption energy. On the h-BN(SW) surface, hydrogen atoms tend to migrate inward from the center of adjacent heptagonal boron nitride rings while coadsorption has a minimal impact on their vertical migration as well as that of H2 molecules. This work provides theoretical insights into the H/H2 trace gas interaction during h-BN wafer-level fabrication for memristor devices.

Single‐Atom Catalyst Induced Amorphous Li2O2 Layer Enduring Lithium–Oxygen Batteries with High Capacity

AbstractAprotic lithium–oxygen batteries (LOBs) may deliver exceptionally high energy density but struggle to attain rapid reversibility and substantial capacity simultaneously, due to typical surface or solution‐formed insulating solid Li2O2. Tuning the structure of Li2O2 to create a large‐area amorphous layer on the cathode is predicted to overcome the multiperformance limitations. Here, an isolated nickel single atom to nitrogen‐doped graphene as a cathode catalyst (Ni─NG SAC) for LOBs is presented via a green click‐trapping strategy. Derived from the maximized exposure of atomic active sites of the cathode, the formation/decomposition mechanisms of Li2O2 are tailored, and a large area of thin Li2O2 amorphous film is achieved. The structure and functions of Ni─NG SAC are explored by theoretical computation and synchrotron radiational investigation. Consequently, the abundant Ni─N4 sites enhance redox kinetics and stand out to deliver an impressive specific discharge/charge capacity of 24 248/17 656 mAh g−1 at 200 mA g−1, together with a long cycle life of over 500 cycles. This study contributes helpful insights to achieve high‐capacity LOBs with long lifespans, by constructing unique single‐atom catalysts to optimize the formation of amorphous discharge Li2O2 products.

Activation of Peroxodisulfate Coupled with Photocatalysis by Pyrrolic N‐Rich Fe‐N4 Sites for High Efficiency Degradation of Tetracycline Hydrochloride

AbstractPhotocatalysis is an efficient technology for the degradation of pollutants. However, there is still much room for improvement in its degradation efficiency. In this study, a pyrrolic N‐rich g‐C3N4 (PN‐g‐C3N4) framework was synthesized with transition metal M (M=Fe, Co, Ni, Cu, Cr, and Mn) atomic sites coordinated onto it. Then, a series of single atomic metals M anchored to PN‐g‐C3N4 (M/PN‐g‐C3N4) are constructed for peroxodisulfate activation. Their order of catalytic activity follows Fe>Cr>Ni>Cu≈Co>Mn, in particular the degradation rates of the TCH for Fe‐PN‐g‐C3N4 are 3.74 times higher than that of undoped PN‐g‐C3N4. These carefully regulated pyrrolic N‐rich Fe sites demonstrate outstanding performance in degrading organic pollutant. As an exemplary model, the Fe/PN‐g‐C3N4 catalyst efficiently drives the catalytic oxidation of TCH through Fenton‐like reaction under visible light, showcasing exceptional cycle stability and a broad effective pH range of 3.0–11.0. The synergy between photocatalysis and Fe doped catalysis results in increased generation and separation of charge carriers, along with the cyclic transformation of the Fe3+/Fe2+ couple. This combination significantly enhances the Fenton‐like performance, making it a highly effective process for pollutant degradation.

Ultra-Thin RuIr Alloy as Durable Electrocatalyst for Seawater Hydrogen Evolution Reaction.

The development of efficient, high-performance catalysts for hydrogen evolution reaction (HER) remains a significant challenge, especially in seawater media. Here, RuIr alloy catalysts are prepared by the polyol reduction method. Compared with single-metal catalysts, the RuIr alloy catalysts exhibited higher activity and stability in seawater electrolysis due to their greater number of reactive sites and solubility resistance. The RuIr alloy has an overpotential of 75 mV@10mA cm-2, which is similar to that of Pt/C (73mV), and can operate stably for 100 hours in alkaline seawater. Density functional theory (DFT) calculations indicate that hydrogen atoms adsorbed at the top sites of Ru and Ir atoms are more favorable for HER and are most likely to be the reactive sites. This work provides a reference for developing highly efficient and stable catalysts for seawater electrolysis.

Anchoring Pt single atoms on specific nitrogen vacancies of carbon nitride to accelerate photogenerated carrier transfer

The anchoring sites of metal single atoms are closely related to photogenerated carrier dynamics and surface reactions. Achieving smooth photogenerated charge transfer through precise design of single-atom anchoring sites is an effective strategy to enhance the activity of photocatalytic hydrogen evolution. In this study, Pt single atoms were loaded onto ultra-thin carbon nitride with two-coordination nitrogen vacancies (VN2c-UCN-Pt) and ultra-thin carbon nitride with three-coordination nitrogen vacancies (VN3c-UCN-Pt). This paper investigated the photocatalytic hydrogen evolution performance and photogenerated carrier behavior of Pt single atoms at different anchoring sites. Surface photovoltage measurements indicated that VN2c-UCN-Pt exhibits a superior carrier separation efficiency compared to VN3c-UCN-Pt. More importantly, the surface photovoltage signal under the presence of H2O molecules revealed a significant decrease. Theoretical calculations suggest that VN2c-UCN-Pt exhibits superior capabilities in adsorbing and activating H2O molecules. Consequently, the photocatalytic hydrogen evolution efficiency of VN2c-UCN-Pt reaches 1774 µmol g−1h−1, which is 1.8 times that of VN3c-UCN-Pt with the same Pt loading. This work emphasized the structure–activity relationship between single-atom anchoring sites and photocatalytic activity, providing a new perspective for designing precisely dispersed single-atom sites to achieve efficient photocatalytic hydrogen evolution.

Robust heterometallic {In2CdO}-Organic framework for efficiently catalyzing CO2 cycloaddition and Knoevenagel condensation

The catalytic performance of MOFs mainly comes from the coordination defects of their metal ions. However, developing promising MOF catalysts with a large number of small coordination molecules on metal ions remains a huge challenge. Herein, we report a highly robust heterometallic {In2CdO}-organic framework of {[In2Cd(CPPDP)(µ3 − OH)(H2O)5](NO3)2⋅2DMF⋅3H2O}n (NUC-103) with scarcely reported [In2Cd(OH)(O2CR)5(H2O)5] clusters (abbreviated as {In2CdO}) as secondary building units (SBUs), each of which contains five associated water molecules, implying that activated host framework can serve as strong Lewis acid. In NUC-103, three rows of {In2CdO} are shaped into hierarchical triangle-nanochannels of 17.42 × 17.98 Å2 and triangle-microchannels of 10.15 × 11.00 Å2 along c axis. On account of the following unique characteristics such as three kinds of active sites (Lewis acid sites of In3+ and Cd2+, Lewis base sites of free Npyridine atoms and electrophilic H-bond donors (HBD) of µ3 − OH moieties), large solvent-free channels, high thermal stability, and resistance to various solvents, NUC-103a is a promising catalytic platform. Catalytic experiments prove that NUC-103a is a significant heterogeneous catalyst for the cycloaddition of CO2 with epoxides with exclusive selectivity and high conversion. In addition, NUC-103a as a bifunctional catalyst displays the high catalytic performance on the Knoevenagel condensation reactions of aldehydes and malononitrile. Therefore, this work not only provides an indium(III) + cadmium(II)-based heterometallic cluster of {In2CdO}, but also provides a valuable insight into designing metal–organic catalytic materials with high defect coordination.

P-d Orbital Hybridization Induced by Asymmetrical FeSn Dual Atom Sites Promotes the Oxygen Reduction Reaction.

With more flexible active sites and intermetal interaction, dual-atom catalysts (DACs) have emerged as a new frontier in various electrocatalytic reactions. Constructing a typical p-d orbital hybridization between p-block and d-block metal atoms may bring new avenues for manipulating the electronic properties and thus boosting the electrocatalytic activities. Herein, we report a distinctive heteronuclear dual-metal atom catalyst with asymmetrical FeSn dual atom sites embedded on a two-dimensional C2N nanosheet (FeSn-C2N), which displays excellent oxygen reduction reaction (ORR) performance with a half-wave potential of 0.914 V in an alkaline electrolyte. Theoretical calculations further unveil the powerful p-d orbital hybridization between p-block stannum and d-block ferrum in FeSn dual atom sites, which triggers electron delocalization and lowers the energy barrier of *OH protonation, consequently enhancing the ORR activity. In addition, the FeSn-C2N-based Zn-air battery provides a high maximum power density (265.5 mW cm-2) and a high specific capacity (754.6 mA h g-1). Consequently, this work validates the immense potential of p-d orbital hybridization along dual-metal atom catalysts and provides new perception into the logical design of heteronuclear DACs.

Amorphous Nanomaterials: Emerging Catalysts for Electrochemical Carbon Dioxide Reduction

AbstractIn the past decades, the rapid depletion of non‐renewable energy sources has caused growing energy crisis and increasing emissions of carbon dioxide (CO2), which aggravates global warming and catastrophic climate change. Electrocatalysis is regarded as an effective method for consuming atmospheric CO2 and simultaneously alleviating the energy problem by converting CO2 into high value‐added chemicals. Amorphous nanomaterials with long‐range disordered structures possess abundant highly unsaturated atomic sites and dangling bonds on their surfaces, thus providing a large number of active sites, and show unique electronic structures compared to their crystalline counterparts due to the distinct atomic arrangements. Therefore, amorphous nanomaterials are recently demonstrated as highly efficient catalysts for diverse electrocatalytic reactions, including electrocatalytic CO2 reduction reaction (CO2RR). Here the rational synthesis and electrocatalytic performance of newly emerging amorphous nanomaterials will be outlined for electrocatalytic CO2RR. Importantly, the intrinsic merits of these amorphous catalysts in CO2RR processes will be summarized and highlighted. Finally, these perspectives on the remaining challenges and some potential future directions in this emerging field will also be provided.

Design of Single-Atom Catalysts on C5N2 for Nitrogen Fixation at Ambient Conditions: A First-Principles Study.

Single atom catalysts (SACs) exhibit the flexible coordination structure of the active site and high utilization of active atoms, making them promising candidates for nitrogen reduction reaction (NRR) under ambient conditions. By the aid of first-principles calculations based on DFT, we have systematically explored the NRR catalytic behavior of thirteen 4d- and 5d-transition metal atoms anchored on 2D porous graphite carbon nitride C N . With high selectivity and outstanding activity, Zr, Nb, Mo, Ta, W and Re-doped C N are identified as potential nominees for NRR. Particularly, Mo@C N possesses an impressive low limiting potential of -0.39 V (corresponding to a very low temperature and atmospheric pressure), featuring the potential determining step involving *N-N transitions to *N-NH via the distal path. The catalytic performance of TM@C N can be well characterized by the adsorption strength of intermediate *N H. Moreover, there exists a volcanic relationship between the catalytic property U and the structure descriptor , which validates the robustness and universality of , combined with our previous study. This work sheds light on the design of SACs with eminent NRR performance.

Electron Donor–Acceptor Activated Single Atomic Sites for Boosting Oxygen Reduction Reaction

AbstractFabricating efficient non‐platinum‐group‐metal catalysts for the oxygen reduction reaction (ORR) in proton‐exchange membrane fuel cells still remains a big challenge. This study creates a unique bamboo‐like architecture of Mn and Fe single atomic sites (SASs) anchored on core‐shell structure of nanopaticles@carbon nanotubes (MnFe SASs/NPs@CNTs) via a precursor route, where the Fe nanoparticles (NPs) (identified as γ‐Fe and Austenite) are confined into CNTs, such an architecture exhibits compelling ORR activity and durability in 0.1 m HClO4. Experiments and calculations both reveal that the electron donor–acceptor paradigm between Mn SASs and Fe NPs launches a lattice‐electron coupling mechanism not only increasing occupation of π‐antibonding orbital in Mn−*O intermediates but also rising Jahn–Teller effect, thereby destabilize the Mn−*O intermediate and eventually facilitate the potential‐limiting step from *O to *OH. Such a coupling activation of the ORR‐inert Mn SASs greatly improves ORR performances of MnFe SASs/NPs@CNTs.

Reversible metal cluster formation on Nitrogen-doped carbon controlling electrocatalyst particle size with subnanometer accuracy

Copper and nitrogen co-doped carbon catalysts exhibit a remarkable behavior during the electrocatalytic CO2 reduction (CO2RR), namely, the formation of metal nanoparticles from Cu single atoms, and their subsequent reversible redispersion. Here we show that the switchable nature of these species holds the key for the on-demand control over the distribution of CO2RR products, a lack of which has thus far hindered the wide-spread practical adoption of CO2RR. By intermitting pulses of a working cathodic potential with pulses of anodic potential, we were able to achieve a controlled fragmentation of the Cu particles and partial regeneration of single atom sites. By tuning the pulse durations, and by tracking the catalyst’s evolution using operando quick X-ray absorption spectroscopy, the speciation of the catalyst can be steered toward single atom sites, ultrasmall metal clusters or large metal nanoparticles, each exhibiting unique CO2RR functionalities.

Cooperative dual single atom Ni/Cu catalyst for highly selective CO2-to-ethanol reduction

The electrochemical CO2-to-ethanol conversion bargains a promising approach to lowering CO2 emission while yielding valuable chemical products. Here, we report the NiCu-SACs/N-C catalysts with cooperative dual heteroactive sites that achieve by far the highest catalytic activity for yielding ethanol with the unprecedented Faradaic efficiency of 92.2 % at the potential of −0.6 V versus RHE. The catalyst exhibits the lowest onset potential of −0.4 V versus RHE to catalyze CO2-to-ethanol conversion. In-operando X-ray absorption spectroscopy provides an interesting observation of restructuring behavior of dynamically generated Cu clusters from atomically distributed Cu single-atoms and reversible structural changes or oxidation states of Cu sites while Ni sites remain unchanged during the catalytic reactions. Our experimental analysis and DFT computation suggest that CO produced on Cu-N4/Ni-N3 cooperative single atom sites undergoes C-C coupling, which is further reduced into ethanol. This strategy provides a new route to design selective and efficient catalysts for CO2-to-ethanol conversion.

Asymmetric Ru-In atomic pairs promote highly active and stable acetylene hydrochlorination

Ru single-atom catalysts have great potential to replace toxic mercuric chloride in acetylene hydrochlorination. However, long-term catalytic stability remains a grand challenge due to the aggregation of Ru atoms caused by over-chlorination. Herein, we synthesize an asymmetric Ru-In atomic pair with vinyl chloride monomer yield (>99.5%) and stability (>600 h) at a gas hourly space velocity of 180 h−1, far surpassing those of the Ru single-atom counterparts. A combination of experimental and theoretical techniques reveals that there is a strong d-p orbital interaction between Ru and In atoms, which not only enables the selective adsorption of acetylene and hydrogen chloride at different atomic sites but also optimizes the electron configuration of Ru. As a result, the intrinsic energy barrier for vinyl chloride generation is lowered, and the thermodynamics of the chlorination process at the Ru site is switched from exothermal to endothermal due to the change of orbital couplings. This work provides a strategy to prevent the deactivation and depletion of active Ru centers during acetylene hydrochlorination.

Fabrication of Ni and Cd co-doped Zn ZIF-L photocatalyst for enhanced solar hydrogen evolution

Recently, photocatalytic H2 production has gained significant attention for its potential to generate clean and renewable energy. In this study, the enhancement of H2 production was examined by introducing various transition metal elements in Zn/Ni/Cd zeolitic imidazole frameworks photocatalysts (ZIF). The photocatalysts were synthesized using a precipitation method in water, resulting in the formation of ZIF-L structures. Increasing the Ni content leads to large particle sizes and typically reduced surface areas, owing to the increased possibility of coordination at the six coordination sites of Ni atoms. The trimetallic Zn/Ni/Cd ZIF at its optimum composition exhibits the highest absorbance and narrowest band gap, consequently yielding the highest average H2 production rate. To address unstable reproducibility from restricted electron transfer in the optimal sample, CdS is added to form a heterojunction and to achieve stable reproducibility. Consequently, improved H2 production is achieved by incorporating imidazole organic ligands into the co-doped trimetallic ZIF-L photocatalyst. Overall, in this study, the synthesis and optimization of ZIF composite photocatalysts are elucidated, providing insights into the design of efficient materials for sustainable energy production.