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The development of advanced electrocatalysts with satisfactory C1 pathway selectivity for the ethanol oxidation reaction (EOR) is critical. Herein, a bubbling CO-induced gelation method is developed in acetic acid at 50 °C to construct single-atom W-doped Pd metallene aerogels (denoted as SA W-Pd MAs) within 1 h. In light of the metallene structural advantages of noble metal aerogels and single-atom W decoration, the resultant SA W-Pd MAs exhibit an outstanding EOR performance with high C1 pathway selectivity. Density functional theory calculations validate that the SA W-Pd MAs greatly improve the formation of the CH

Effective glucose surveillance provides a strong guarantee for the high-quality development of human health. Au nanomaterials possess compelling applications in nonenzymatic electrochemical glucose biosensors owing to superior catalytic performances and intriguing biocompatibility properties. However, it has been a grand challenge to accurately control the architecture and composition of Au nanomaterials to optimize their optical, electronic, and magnetic properties for further improving the performance of electrocatalytic sensing. Herein, ultra-low content Bi-anchored Au aerogels are synthesized via a one-step reduction strategy. Benefiting from the unique structure of aerogels as well as the synergistic effect between Au and Bi, the optimized Au

Developing highly active and selective advanced nanozymes for enzyme-mimicking catalysis remains a long-standing challenge for basic research and practical applications. Herein, we grafted a chiral histidine- (His-) coordinated copper core onto Zr-based metal-organic framework (MOF) basic backbones to structurally mirror the bimetal active site of natural catechol oxidase. Such a biomimetic fabricated process affords MOF-His-Cu with catechol oxidase-like activity, which can catalyze dehydrogenation and oxidation of

Graphite carbon nitride (g-C3N4) is a significant non-metal photocatalyst, but still challenging for photocatalytic degradation of pollutants because of its poor visible light utilization, easy recombination of photo-generated carriers and low surface reactive reaction sites. In this paper, perylene diimide (PDI), an electron-deficient building block for constructing n-type organic semiconductors, was introduced into the framework of g-C3N4 (PDI-g-C3N4) to build polymer with donor–acceptor structure for energy band amelioration, achieving the most expanded visible light response up to date. Besides, a large dihedral angle (90°) induced by PDI moiety in PDI-g-C3N4 changes the molecular aggregation behavior according to calculations, which is advantageous to increase surface area for the reactive site exposure. The most promising functional photocatalyst PDI-g-C3N4/MIL is constructed by in-situ generation of NH2-MIL-53(Fe) on the surface of PDI-g-C3N4 to further facilitate the separation and transfer of interfacial photo-induced carriers. Through a finely adjusting ratio of PDI-g-C3N4 in heterojunction, the target material of PDI-g-C3N4/MIL exhibits superior activity for the photodegradation of organic pollutants in the presence of H2O2 and visible light illumination, providing potential direction in practical application for wastewater treatment.

Rational design and construction of electrochemical sensing platforms with high sensitivity and selectivity is one of the challenges in practical application. Although single-atom catalysts (SACs) have attracted extensive attention, atomically dispersed metal catalysts (ADCs) with multi-atom sites can further compensate for the deficiencies of SACs, which have gradually been a research hotspot in recent years. Herein, atomically dispersed Ru

Design of highly active carbon nanozymes and further establishment of ultrasensitive biosensors remain a challenge. Herein, hierarchically porous carbon nanozymes with sulfur (S)/nitrogen (N) codoping (SNC) were developed. Compared with N-doped carbon (NC) nanozymes, SNC nanozymes have a smaller Michaelis-Menten constant and higher specific activities, demonstrating that the S-doping in SNC nanozymes could not only enhance their affinity toward substrates but also improve their catalytic performance. These results may be caused by the synergistic effect of heteroatoms (S and N). Because of the good enzyme-like activity, the proposed SNC nanozymes were exploited to the colorimetric detection of the total antioxidant capacity (TAC) using ascorbic acid as a typical model with a limit of detection of 0.08 mM. Because of its high sensitivity and selectivity and encouraging performance, the detection method presented practical feasibility for the TAC assay in commercial beverages. This work paves a way to design the highly active carbon nanozymes and expand their applications in the construction of high-performance biosensors.

A highly sensitive photoelectrochemical (PEC) sensing platform was constructed for Hg2+ determination based on the Schottky heterojunction between an emerging 2D material Ti3C2TX MXene and a promising semiconductor material BiVO4. Through simply spin-coating the single-layer Ti3C2TX onto the surface of BiVO4 film, the modified electrode exhibited significantly enhanced PEC activity. However, the boost in photocurrent could be noticeably suppressed due to the consumption of hole-scavenging agents (reduced glutathione) by the added Hg2+. Owing to the selective decrease in the photocurrent with the addition of Hg2+, the PEC sensor based on BiVO4/Ti3C2TX displayed a wide linear range from 1 pM to 2 nM with the limit of detection down to 1 pM. Moreover, the PEC sensor also exhibited satisfactory accuracy and repeatability in practical sample water, the Yangtze River water, demonstrating the great potential for monitoring heavy metal ions in natural water resources.

In this work, Co–N-doped carbon nanosheet (Co-NCS), obtained through a self-assembly strategy and subsequent pyrolysis process, was reported as an efficient ORR catalyst. Combining the unique 2D architecture and high N-doping level, the optimized Co-NCS exhibits a superior ORR performance with more positive onset potential (0.96 V) and half-wave potential (0.93 V) than those of commercial Pt/C under alkaline conditions. Additionally, the optimized catalyst also displays desirable ORR activity in acidic media, approaching that of commercial Pt/C. Significantly, the synergistic catalysis is demonstrated through selective etching of active species, holding great potential in an in-depth understanding of the contributions of CoNₓ and Co@C NPs in catalysts. Furthermore, the zinc–air batteries assembled with the optimized Co-NCS as the air cathode outperform the Pt-based zinc–air batteries. This finding sheds light on the synthesis of ORR catalysts and the exploration of their application in energy conversion systems.

The traditional luminol-H2 O2 electrochemiluminescence (ECL) sensing platform suffers from self-decomposition of H2 O2 at room temperature, hampering its application for quantitative analysis. In this work, for the first time we employ iron single-atom catalysts (Fe-N-C SACs) as an advanced co-reactant accelerator to directly reduce the dissolved oxygen (O2 ) to reactive oxygen species (ROS). Owing to the unique electronic structure and catalytic activity of Fe-N-C SACs, large amounts of ROS are efficiently produced, which then react with the luminol anion radical and significantly amplify the luminol ECL emission. Under the optimum conditions, a Fe-N-C SACs-luminol ECL sensor for antioxidant capacity measurement was developed with a good linear range from 0.8 μm to 1.0 mm of Trolox.

Tuning electrocatalysts via interface engineering is widely adopted as a valid way to manipulate the electrocatalytic activity. Herein, the interface engineering of PdCu aerogels is successfully achieved by the integration of an ionic liquid (IL), which not only accelerates the gelation kinetics but also leads to the modulation of the interface electronic properties, enabling IL functionalized PdCu aerogels (IL/PdCu) as advanced electrocatalysts for the methanol oxidation reaction (MOR) with splendid electrocatalytic activity. Density functional theory (DFT) calculations also demonstrate that IL-involved interface engineering dramatically reduces the chemisorption energy of CO-containing intermediates and thus significantly boosts the MOR performance. Furthermore, direct methanol fuel cells (DMFCs) using an IL/Pd3Cu1 anode catalyst exhibit a higher power density than those containing Pd3Cu1 and commercial Pd catalysts. This work highlights the superiority of designing advanced electrocatalysts by interface engineering.

The investigations on the generation, separation, and interfacial-redox-reaction processes of the photoinduced carriers are of paramount importance for realizing efficient photoelectrochemical (PEC) detection. However, the sluggish interfacial reactions of the photogenerated carriers, combined with the need for appropriate photoactive layers for sensing, remain challenges for the construction of advanced PEC platforms. Here, as a proof of concept, well-defined Fe single-atom catalysts (Fe SACs) were integrated on the surface of semiconductors, which amplified the PEC signals

Tremendous efforts have been made in developing single-atomic site catalysts (SASCs) for oxygen reduction reaction (ORR), which is regarded as a pivotal cornerstone in electrochemical energy conversion. However, SASCs for ORR have not been explored for electrochemical sensing. Herein, a template-sacrificed strategy is reported for the synthesis of atomically dispersed Ir SASCs, serving as a sensing platform to detect organophosphorus pesticides (OPs) with high sensitivity and selectivity. Owing to abundant Ir single-atom active sites, Ir SASCs show excellent ORR activity and stability in a neutral medium. It is found that the ORR activity of Ir SASCs can be inhibited by thiocholine, which is the hydrolysate of acetylthiocholine. After being integrated with acetylcholinesterase (AChE), the AChE-Ir SASC-based electrochemical sensor is established and shows a superior sensitivity, which shows a wide detection range of 0.5-500 ng mL

Developing effective electrocatalysts to achieve highly sensitive and selective detection of heavy metal ions is one of the challenges in the field of environmental monitoring. Herein, bismuth (Bi) metallene (Bi-ene) in atomic thickness is successfully synthesized and applied as a conceptual application in electrochemical sensors for the detection of lead ion (Pb

Enzyme immobilization plays an essential role in solving the problems of the inherently fragile nature of enzymes. Although prominent stability and reuse of enzymes can be achieved by enzyme immobilization, their bioactivity and catalytic efficiency will be adversely affected. Herein, PdCu hydrogel nanozymes with a hierarchically porous structure were used to immobilize horseradish peroxidase (HRP) to obtain PdCu@HRP. In addition to the improvement of stability and reusability, PdCu@HRP displayed synergistically enhanced activities than native HRP and PdCu hydrogels. Not only the specific interactions between PdCu hydrogel nanozymes and enzymes but also the enrichment of substrates around enzymes by electrostatic adsorption of hydrogels was proposed to expound the enhanced catalytic activity. Accordingly, by taking advantage of the excellent catalytic performance of the PdCu@HRP and the glucose oxidase encapsulated in zeolitic imidazolate framework-8, colorimetric biosensing of the carcinoembryonic antigen via catalytic cascade reactions for achieving signal amplification was performed. The obtained biosensor enhanced the detection sensitivity by approximately 6.1-fold as compared to the conventional HRP-based enzyme-linked immunosorbent assay, demonstrating the promising potential in clinical diagnosis.

Ternary PtRuCu aerogels are facilely synthesized by one-step in situ reduction. The formation of ternary PtRuCu aerogels can be completed within 2 hours owing to the accelerated gelation kinetics. Because of the unique porous architectures and synergistic effect, the optimized Pt4Ru1Cu5 aerogels exhibited good electrochemical performance for methanol oxidation reaction.

Cell-free enzymatic catalysis (CFEC) is emerging biotechnology that simulates biological transformations without living cells. However, the high cost of separation and preparation of the enzyme has hindered the practical application of the CFEC. Enzyme immobilization technologies using solid supports to stabilize enzymes have been regarded as an efficient strategy to address this issue. Nevertheless, the activity and stability of the immobilized enzymes are still crucial challenges for working in vitro. Herein, an enzyme immobilization platform is developed by using PtCu hydrogels coated with amorphous metallic-organic frameworks (MOFs) as multifunctional carriers to encapsulate horseradish peroxidase (HRP). Specifically, PtCu hydrogels acting as a "reservoir of metal ions" can interact with the immobilized enzyme and facilitate electron transfer, leading to the boosted enzyme catalytic performances. Furthermore, amorphous MOFs on the surface of PtCu hydrogels serve as an "armor" to protect the internal enzymes from various perturbation environments. The resultant enzyme immobilization platform (PtCu@HRP@ZIF-8) not only shows an approximately 2.4-fold enhanced activity compared with free enzyme but also exhibits improved stability against harsh conditions. The PtCu@HRP@ZIF-8-based biosensor is constructed for sensitive sensing of organophosphorus pesticides (OPs). The proposed biosensor exhibits a favorable linear relationship with the concentration of paraoxon-ethyl from 6 to 800 ng/mL, with a low detection limit of 1.8 ng/mL. This work reveals the promising potential of our proposed enzyme immobilization platform in practical applications.

Noble metal-based nanomaterials have been a hot research topic during the past few decades. Particularly, self-assembled porous architectures have triggered tremendous interest. At the forefront of porous nanostructures, there exists a research endeavor of noble metal aerogels (NMAs), which are unique in terms of macroscopic assembly systems and three-dimensional (3D) porous network nanostructures. Combining excellent features of noble metals and the unique structural traits of porous nanostructures, NMAs are of high interest in diverse fields, such as catalysis, sensors, and self-propulsion devices. Regardless of these achievements, it is still challenging to rationally design well-tailored NMAs in terms of ligament sizes, morphologies, and compositions and profoundly investigate the underlying gelation mechanisms. Herein, an elaborate overview of the recent progress on NMAs is given. First, a simple description of typical synthetic methods and some advanced design engineering are provided, and then, the gelation mechanism models of NMAs are discussed in detail. Furthermore, promising applications particularly focusing on electrocatalysis and biosensors are highlighted. In the final section, brief conclusions and an outlook on the existing challenges and future chances of NMAs are also proposed.

Highlights Secondary-atom-doped strategy was proposed to synthesize single-atom electrocatalyst.The increase in both the density of active sites and their intrinsic activity was achieved simultaneously.The resultant single-atom catalyst shows outstanding ORR activity in acidic media. Electronic supplementary material The online version of this article (10.1007/s40820-020-00502-5) contains supplementary material, which is available to authorized users., Single-atom catalysts (SACs) with nitrogen-coordinated nonprecious metal sites have exhibited inimitable advantages in electrocatalysis. However, a large room for improving their activity and durability remains. Herein, we construct atomically dispersed Fe sites in N-doped carbon supports by secondary-atom-doped strategy. Upon the secondary doping, the density and coordination environment of active sites can be efficiently tuned, enabling the simultaneous improvement in the number and reactivity of the active site. Besides, structure optimizations in terms of the enlarged surface area and improved hydrophilicity can be achieved simultaneously. Due to the beneficial microstructure and abundant highly active FeN5 moieties resulting from the secondary doping, the resultant catalyst exhibits an admirable half-wave potential of 0.81 V versus 0.83 V for Pt/C and much better stability than Pt/C in acidic media. This work would offer a general strategy for the design and preparation of highly active SACs for electrochemical energy devices. Electronic supplementary material The online version of this article (10.1007/s40820-020-00502-5) contains supplementary material, which is available to authorized users.

A highly sensitive photoelectrochemical (PEC) sensing platform was constructed for Hg

Single-atom nanozymes (SAzymes), as novel nanozymes with atomically dispersed active sites, are of great importance in the development of nanozymes for their high catalytic activities, the maximum utilization efficiency of metal atoms, and the simple model of active sites. Herein, the peroxidase-like SAzymes with high-concentration Cu sites on carbon nanosheets (Cu-N-C) were synthesized through a salt-template strategy. With the densely distributed active Cu atoms (∼5.1 wt %), the Cu-N-C SAzymes exhibit remarkable activity to mimic natural peroxidase. Integrating Cu-N-C SAzymes with natural acetylcholinesterase and choline oxidase, three-enzyme-based cascade reaction system was constructed for the colorimetric detection of acetylcholine and organophosphorus pesticides. This work not only provides a strategy to synthesize SAzymes with abundant active sites but also gives some new insights for robust nanozyme biosensing systems.

The establishment of advanced electrocatalysts with remarkable performance and cost effectiveness for the oxygen evolution reaction (OER) is an emerging need for the production of clean hydrogen fuel. In this work, three-dimensional (3D) amorphous NiFeIrx/Ni core–shell nanowire@nanosheets (NW@NSs) are successfully synthesized through a facile one-step reduction process with atomically isolated Ir atoms anchored on an NiFe-based core. By taking advantage of their unique structure and composition, the resultant NiFeIrx/Ni NW@NSs have a high electrocatalytic activity for OER which can deliver current densities of 10 and 100 mA cm–2 at overpotentials as low as 200 and 250 mV in 1 M KOH, respectively. It is worth noting that NiFeIrx/Ni NW@NSs exhibit outstanding long-term stability over 12 h at a current density of 10 mA cm–2. Theoretical calculations also reveal that the intrinsic activity of the resultant NiFeIrx/Ni NW@NSs is significantly enhanced upon the addition of Ir single atoms, highlighting the criti...

The development of highly active biomimetic catalysts with peroxidase (POD)-like activity and realization of vivid mimicking of the active sites of natural enzymes still remains a huge challenge. Herein, atomically dispersed Fe atoms on hierarchically S/N co-doped porous carbon (FeSNC) featured with the unsymmetrically coordinated Fe-N3S1 as active sites were synthesized by a template-assisted method. The resultant FeSNC exhibits higher POD-like activity than FeNC featured with Fe-N4 sites. Owing to the S doping-induced geometric/electronic effects, Fe-N3S1 not only lengthens the O O bonding distances of adsorbed H2O2 but also accelerates the electronic transfer between Fe and O, decreasing the energy barrier of the formation of the active intermediate and thus achieving the boosted POD-like activity. Finally, the sensitive detection of organophosphorus pesticides was performed by adjusting the POD-like activity of FeSNC, exhibiting satisfactory sensitivity and selectivity. This work provides great promise for the accurate design of single-atom catalysts for vivid mimicking the function of natural enzymes.

The complex structure of nanomaterial causes great difficulty in identifying active sites of nanozymes and getting to the bottom of the catalytic mechanism. In this report, single-atom Bi-anchored Au (BiSA@Au) hydrogels were synthesized through a one-step reduction strategy, which enables the precise regulation of the nanozyme activity and specificity at the atomic scale and the in-depth understanding of their catalytic nature. Due to the single-atom Bi doping, the BiSA@Au hydrogels showed previously unachieved peroxidase (POD)-like activity, while the doped single Bi atoms had negligible effects on the enhancements of the other closely related redox enzyme-like activities. Density functional theory verified that the introduction of single Bi atoms not only enhances the adsorption of H2O2 but also decreases the potential barriers for *OOH generation, leading to the boosted POD-like activity. Taking advantage of the unique porous nanowire networks of BiSA@Au hydrogels, a nanozyme/natural enzyme hybrid cascade reaction system was fabricated to achieve the sensitive colorimetric biosensor for glucose. This work paved a new route to rationally design functional nanozymes at the atomic scale, achieving the significant enhancement of POD-like activity with exceptional specificity.

Developing single-atomic site (SAS) catalysts for oxygen reduction reaction (ORR) with superior activities in the renewable-energy initiatives is critical but remains challenging. Herein, exceptional SAS Fe boosted by adjacent graphene-encapsulated Fe3C nanocrystals (Fe3C@C-Fe SAS) is constructed for ORR. Because of the strong synergistic effects between SAS Fe and Fe3C@C nanocrystals, Fe3C@C-Fe SAS shows robust ORR performance in the neutral electrolyte with the onset potential of 0.99 V and negligible activity loss after 30 k cycles of an accelerated durability test, much better than that of Pt/C catalyst. Notably, the integrated zinc-air battery in the neutral system exhibits an outstanding peak power density of 74.8 mW/cm2 and durability over 100 h, representing a state-of-the-art PGM-free ORR catalyst. More importantly, the density functional theory (DFT) calculations shed light on that the introduction of Fe3C@C nanocrystals is favorable for the activation of O2 molecules and desorption of OH* on the Fe SAS, resulting in accelerated reaction kinetics and promising ORR activity. Given the explicit structure-performance relationships for Fe3C@C-Fe SAS, this work provides a new strategy for the design of more advanced energy-based electrocatalysts.

Developing efficient nonprecious metal electrocatalysts is urgently needed to promote the sluggish kinetics of oxygen evolution reaction (OER). Transition metals-based layered double hydroxides (LDH) have been considered as highly active OER catalysts, while low conductivity and limited active site exposures hinder their further applications. Herein, CoNi LDH/Ti3C2Tx MXene is facilely constructed by using Ti3C2Tx coated nickel foam as support to load CoNi LDH through electrodeposition. Surprisingly, a significant enhancement in OER activity of pristine CoNi LDH is achieved due to the metallic conductivity and hydrophilic and electronegative surface of Ti3C2Tx. Importantly, CoNi LDH/Ti3C2Tx displays prominent OER performance and stability in alkaline medium, which exhibits a low overpotential of 257.4 mV to reach current density of 100 mA/cm2 and a small Tafel slope of 68 mV/dec. The experimental and calculated results demonstrate electron transfer from CoNi LDH to Ti3C2Tx plays a significant role in boosting OER activity by lowering the binding strength of intermediates.

Interface engineering of electrocatalysts is a promising strategy to modulate their corresponding physicochemical properties. Compared with sulfides and selenides, the studies related to the interface engineering of the transition metal tellurides for oxygen evolution reaction (OER) remain scarce, regardless of their higher electrical conductivity and mass transport rate. Herein, a class of NiFe LDH/NiTe composites was successfully synthesized for enhancing the OER performance by partial chemical etching of nickel foam to prepare NiTe nanoarrays, and subsequently depositing NiFe LDH with a hydrothermal process. Based on experimental and calculated results, the NiFe LDH/NiTe composite is observed with a more intensive interface rather than a simple physical mixture, leading to enhanced charge transfer and improved reaction kinetics resulting from reduced binding strength of intermediates. Therefore, the resultant NiFe LDH/NiTe exhibits outstanding OER activity in alkaline solution with an overpotential of 228 mV at the current density of 50 mA/cm2.

In this work, a Z-scheme TiO2/Ti3C2Tx/Cu2O heterostructure was well designed and fabricated by in situ generating TiO2 NPs on Ti3C2Tx MXenes and subsequently introducing Cu2O via one-step hydrothermal reaction. The obtained heterojunction exhibits good photoelectrochemical (PEC) activity with dissolved O2 as electron scavenger, during which H2O2 is produced as intermediates to further capture the photo generated electrons. However, H2O2 is consumed with the addition of glucose, leading to the accumulation of photoelectrons on the heterojunction and a significant decay in the photocurrent signal. On this basis, TiO2/Ti3C2Tx/Cu2O was employed as photocathode to construct a self-powered PEC sensor for glucose detection, and the photocurrent of TiO2/Ti3C2Tx/Cu2O linearly decreased with the increasing logarithm of glucose concentration in a wide range of 100 nM to 10 μM with a low detection limit of 33.75 nM (S/N = 3). Moreover, the fabricated PEC sensor possessed favourable feasibility and high selectivity for the determination of glucose in biomedical samples, suggesting a bright future in the application of clinical diagnosis.

We report a computational study, using the "moments method" [Y. Gao and M. Daw, Modelling Simul. Mater. Sci. Eng. 23 045002 (2015)], of the anharmonicity of the vibrational modes of single-walled carbon nanotubes. We find that modes with displacements largely within the wall are more anharmonic than modes with dominantly radial character, except for a set of modes that are related to the radial breathing mode which are the most anharmonic of all. We also find that periodicity of the calculation along the tube length does not strongly affect the anharmonicity of the modes, but that the tubes with larger diameter show more anharmonicity. Comparison is made with available experiments and other calculations.

We report a computational study of the anharmonicity of the vibrational modes of various individual fullerenes using the "moments method" [Y. Gao and M. Daw, Modelling Simul. Mater. Sci. Eng. 23 045002 (2015)] with a Tersoff-style potential for carbon. We find that the frequencies of all vibrational modes drop systematically with temperature and the sizes of the individual fullerenes do not affect strongly the anharmonicity of the modes. Comparison is made with available experiments.

Enzyme-linked immunosorbent assay (ELISA) has been widely used in the area of biological analysis, while there are still some challenges getting in the way to ensure both excellent sensitivity and reliable accuracy. To overcome these obstacles, we simulated the “smart” sense-and-treat carriers in a drug delivery system to fabricate an improved ELISA, employing zeolitic imidazolate framework-8 (ZIF-8) as the carrier to deliver the tracer agent carbon dots (CDs) and the “drug” thymolphthalein (TP), which was referred to as a “sense-and-treat” ELISA. In the “sense” part, the strong fluorescence intensity of CDs could be observed directly to achieve the sensitive detection of the target. In the “treat” part, after stimulation of alkaline solution, TP was released from ZIF-8 carriers and generated a color change with an obvious absorption, which was beneficial for increasing the sensitivity of this ELISA due to the high loading of the TP. Finally, we took carcinoembryonic antigen (CEA) as a model and performed dual-modal detection using this improved “sense-and-treat” ELISA to accomplish quantitative determinations sensitively and accurately. In addition, the results indicated by the two parts kept good concordance, which could demonstrate the reliable accuracy of this ELISA.

Single-atom catalysts (SACs) have attracted extensive attention in the catalysis field because of their remarkable catalytic activity, gratifying stability, excellent selectivity, and 100% atom utilization. With atomically dispersed metal active sites, Fe-N-C SACs can mimic oxidase by activating O2 into reactive oxygen species, O2 - • radicals. Taking advantages of this property, single-atom nanozymes (SAzymes) can become a great impetus to develop novel biosensors. Herein, the performance of Fe-N-C SACs as oxidase-like nanozymes is explored. Besides, the Fe-N-C SAzymes are applied in biosensor areas to evaluate the activity of acetylcholinesterase based on the inhibition toward nanozyme activity by thiols. Moreover, this SAzymes-based biosensor is further used for monitoring the amounts of organophosphorus compounds.

We investigate through an atomistic method the effects of anharmonicity on the dispersion of flexural modes of graphene. Using a calculation based on ensemble averages of correlations among displacements and forces, we calculate the temperature-dependent frequencies for a semiempirical potential for graphene. We find that the dispersion relation of the flexural modes of graphene is renormalized by anharmonic coupling to other modes. Our calculations confirm that the anharmonic continuum results of Mariani and von Oppen [Phys. Rev. Lett. 100, 076801 (2008)] hold in detail for small wave number and at low temperatures. We examine the deviation from the continuum result outside of that range.