Surface Molecular Encapsulation with Cyclodextrin in Promoting the Activity and Stability of Fe Single-Atom Catalyst for Oxygen Reduction Reaction

Fe single-atom catalysts(Fe-SACs)have been extensively studied as a highly efficient electrocatalyst toward the oxygen reduction reaction(ORR).Nonetheless,they suffer from stability issue induced by dissolution of Fe metal center and the OH^(−)blocking.Herein,a surface molecular engineering strategy is developed by usingβ-cyclodextrins(CDs)as a localized molecular encapsulation.The CD-modified Fe-SAC(Fe-SNC-β-CD)shows obviously improved activity toward the ORR with 0.90 V,4.10 and 4.09 mA cm^(-2)for E_(1/2),J_(0)and Jk0.9,respectively.Meanwhile,the Fe-SNC-β-CD shows the excellent long-term stability against aggressive stress and the poisoning.It is confirmed through electrochemical investigation that modification ofβ-CD can,on one hand,regulate the atomic Fe coordination chemistry through the interaction between the CD and FeN_(x) moiety,while on the other mitigate the strong adsorption of OH^(−)and function as protective barrier against the poisoning molecules leading to enhanced ORR activity and stability for the Fe-SACs.The molecular encapsulation strategy demonstrates the uniqueness of post-pyrolysis surface molecular engineering for the design of single-atom catalyst.

Functional annotation map of natural compounds in traditional Chinese medicines library: TCMs with myocardial protection as a case

The chemical complexity of traditional Chinese medicines(TCMs) makes the active and functional annotation of natural compounds challenging. Herein, we developed the TCMs-Compounds Functional Annotation platform(TCMs-CFA) for large-scale predicting active compounds with potential mechanisms from TCM complex system, without isolating and activity testing every single compound one by one. The platform was established based on the integration of TCMs knowledge base, chemome profiling, and high-content imaging. It mainly included:(1) selection of herbal drugs of target based on TCMs knowledge base;(2) chemome profiling of TCMs extract library by LC-MS;(3) cytological profiling of TCMs extract library by high-content cell-based imaging;(4) active compounds discovery by combining each mass signal and multi-parametric cell phenotypes;(5) construction of functional annotation map for predicting the potential mechanisms of lead compounds. In this stud TCMs with myocardial protection were applied as a case study, and validated for the feasibility and utility of the platform. Seven frequently used herbal drugs(Ginseng, etc.) were screened from 100,000 TCMs formulas for myocardial protection and subsequently prepared as a library of 700 extracts. By using TCMs-CFA platform, 81 lead compounds, including 10 novel bioactive ones, were quickly identified by correlating 8089mass signals with 170,100 cytological parameters from an extract library. The TCMs-CFA platform described a new evidence-led tool for the rapid discovery process by data mining strategies, which is valuable for novel lead compounds from TCMs. All computations are done through Python and are publicly available on GitHub.

Dual-metal single-atomic catalyst:The challenge in synthesis,characterization,and mechanistic investigation for electrocatalysis

Dual-metal single-atom catalysts(DACs),featuring high atomic utilization efficiency,excellent selectivity,and stability originating from the atomically dispersed nature,have emerged as a new frontier in heterogeneous electrocatalysis due to the synergistic effect between diversified metal active sites in promoting their catalytic activity.In this review,the recent progress and development on the syntheses,characterizations,theoretical uniqueness,and applications for various catalytic reactions and devices(oxygen reduction reaction,oxygen evolution reaction,hydrogen evolution reaction,CO_(2) reduction reaction,N2 reduction reaction,proton exchange membrane fuel cells)are summarized and reviewed.Specifically,the synergistic effect between the two metal centers and electronic structures of catalysts is systematically discussed.Moreover,the future challenges and prospects in developing practical DACs are proposed as a possible direction for further investigation.

Rational design of Fe-N-C electrocatalysts for oxygen reduction reaction:From nanoparticles to single atoms

As an alternative energy,hydrogen can be converted into electrical energy via direct electrochemical conversion in fuel cells.One important drawback of full cells is the sluggish oxygen reduction reaction(ORR)promoted by the high-loading of platinum-group-metal(PGM)electrocatalysts.Fe-N-C family has been received extensive attention because of its low cost,long service life and high oxygen reduction reaction activity in recent years.In order to further enhance the ORR activity,the synthesis method,morphology regulation and catalytic mechanism of the active sites in Fe-N-C catalysts are investigated.This paper reviews the research progress of Fe-N-C from nanoparticles to single atoms.The structure-activity relationship and catalytic mechanism of the catalyst are studied and discussed,which provide a guidance for rational design of the catalyst,so as to promote the more reasonable design of Fe-N-C materials.