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1.
Nat Commun ; 15(1): 2327, 2024 Mar 14.
Article En | MEDLINE | ID: mdl-38485966

Polymerization-driven removal of pollutants in advanced oxidation processes (AOPs) offers a sustainable way for the simultaneous achievement of contamination abatement and resource recovery, supporting a low-carbon water purification approach. However, regulating such a process remains a great challenge due to the insufficient microscopic understanding of electronic structure-dependent reaction mechanisms. Herein, this work probes the origin of catalytic pollutant polymerization using a series of transition metal (Cu, Ni, Co, and Fe) single-atom catalysts and identifies the d-band center of active site as the key driver for polymerization transfer of pollutants. The high-valent metal-oxo species, produced via peroxymonosulfate activation, are found to trigger the pollutant removal via polymerization transfer. Phenoxyl radicals, identified by the innovative spin-trapping and quenching approaches, act as the key intermediate in the polymerization reactions. More importantly, the oxidation capacity of high-valent metal-oxo species can be facilely tuned by regulating their binding strength for peroxymonosulfate through d-band center modulation. A 100% polymerization transfer ratio is achieved by lowering the d-band center. This work presents a paradigm to dynamically modulate the electronic structure of high-valent metal-oxo species and optimize pollutant removal from wastewater via polymerization.

2.
Adv Mater ; 36(14): e2310657, 2024 Apr.
Article En | MEDLINE | ID: mdl-38193844

Extracting lithium selectively and efficiently from brine sources is crucial for addressing energy and environmental challenges. The electrochemical system employing LiMn2O4 (LMO) electrodes has been recognized as an effective method for lithium recovery. However, the lithium selectivity and stability of LMO need further enhancement for its practical applications. Herein, the Al-doped LMO with reduced lattice constant is successfully fabricated through a facile one-step solid-state sintering method, leading to enhanced lithium selectivity. The reduced lattice constant in Al-doped LMO is proved through spectroscopic analyses and theoretic calculations. Compared to the original LMO, the Al-doped LMO (LiAl0.05Mn1.95O4, LMO-Al0.05) exhibits highercapacitance, lower resistance, and improved stability. Moreover, the LMO-Al0.05 with reduced lattice constant can offer higher Li+ diffusion coefficient and lower intercalation energy revealed by cyclic voltammetry and multiscale simulations. When employed in hybrid capacitive deionization (CDI), the LMO-Al0.05 obtains a Li+ intercalation capacity of 21.7 mg g-1 and low energy consumption of 2.6 Wh mol-1 Li+. Importantly, the LMO-Al0.05 achieves a high Li+ extraction percentage (≈86%) with Li+/Na+ and Li+/Mg2+ selectivity of 1653.8 and 434.9, respectively, in synthetic brine. The results demonstrate that the Al-doped LMO with reduced lattice constant could be a sustainable solution for electrochemical lithium extraction.

3.
Nat Commun ; 15(1): 193, 2024 Jan 02.
Article En | MEDLINE | ID: mdl-38167494

Direct electrosynthesis of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction presents a burgeoning alternative to the conventional energy-intensive anthraquinone process for on-site applications. Nevertheless, its adoption is currently hindered by inferior H2O2 selectivity and diminished H2O2 yield induced by consecutive H2O2 reduction or Fenton reactions. Herein, guided by theoretical calculations, we endeavor to overcome this challenge by activating a main-group Pb single-atom catalyst via a local micro-environment engineering strategy employing a sulfur and oxygen super-coordinated structure. The main-group catalyst, synthesized using a carbon dot-assisted pyrolysis technique, displays an industrial current density reaching 400 mA cm-2 and elevated accumulated H2O2 concentrations (1358 mM) with remarkable Faradaic efficiencies. Both experimental results and theoretical simulations elucidate that S and O super-coordination directs a fraction of electrons from the main-group Pb sites to the coordinated oxygen atoms, consequently optimizing the *OOH binding energy and augmenting the 2e- oxygen reduction activity. This work unveils novel avenues for mitigating the production-depletion challenge in H2O2 electrosynthesis through the rational design of main-group catalysts.

4.
Environ Sci Technol ; 57(51): 21540-21549, 2023 Dec 26.
Article En | MEDLINE | ID: mdl-38086095

Interfacial electron transfer (IET) is essential for chemical and biological transformation of pollutants, operative across diverse lengths and time scales. This Perspective presents an array of multiscale molecular simulation methodologies, supplemented by in situ monitoring and imaging techniques, serving as robust tools to decode IET enhancement mechanisms such as interface molecular modification, catalyst coordination mode, and atomic composition regulation. In addition, three IET-based pollutant transformation systems, an electrocatalytic oxidation system, a bioelectrochemical spatial coupling system, and an enzyme-inspired electrocatalytic system, were developed, demonstrating a high effect in transforming and degrading pollutants. To improve the effectiveness and scalability of IET-based strategies, the refinement of these systems is necessitated through rigorous research and theoretical exploration, particularly in the context of practical wastewater treatment scenarios. Future endeavors aim to elucidate the synergy between biological and chemical modules, edit the environmental functional microorganisms, and harness machine learning for designing advanced environmental catalysts to boost efficiency. This Perspective highlights the powerful potential of IET-focused environmental remediation strategies, emphasizing the critical role of interdisciplinary research in addressing the urgent global challenge of water pollution.


Environmental Pollutants , Water Pollutants, Chemical , Electrons , Electron Transport , Oxidation-Reduction , Catalysis , Water Pollutants, Chemical/analysis
5.
Water Res ; 246: 120743, 2023 Nov 01.
Article En | MEDLINE | ID: mdl-37857007

The exploring of molecular-level heterogeneity of dissolved organic matter (DOM) in highly connected water bodies is of great importance for pollution tracing and lake management, and provides new perspectives on the transformations and fate of DOM in aquatic systems. However, the inherent homogeneity of DOM in connected water bodies poses challenges for its heterogeneity analysis. In this work, an innovative method combining fluorescence spectroscopy, high-resolution mass spectrometry (HRMS), and cluster analysis was developed to reveal the heterogeneity of DOM in highly connected water bodies at the molecular level. We detected 4538 molecules across 36 sampling sites in Chaohu Lake using HRMS. Cluster analysis based on excitation-emission matrix (EEM) data effectively divided the sampling sites into four clusters, representing the water bodies from West Chaohu Lake, East Chaohu Lake, agricultural land, and urban areas. Analysis of DOM in the western and eastern parts of the lake revealed that aerobic degradation led to a decrease in CHOS and aliphatic compounds, alongside an increase in CHO and highly unsaturated and phenolic compounds. Furthermore, we unveiled the characteristics and sources of heterogeneity in DOM from agricultural land and urban areas. Our method accurately captured the heterogeneous distribution of DOM in the lake and revealed the heterogeneous composition of DOM at molecular level. This work underscores the importance of integrating complementary spectroscopic analyses with HRMS in DOM research with similar compositions.


Dissolved Organic Matter , Humic Substances , Mass Spectrometry , Humic Substances/analysis , Agriculture , Spectrometry, Fluorescence , Lakes/chemistry , Water/analysis
6.
Water Res ; 246: 120681, 2023 Nov 01.
Article En | MEDLINE | ID: mdl-37801982

The synergistic effect of protein-silica complexation leads to exacerbated membrane fouling in the membrane desalination process, exceeding the individual impacts of silica scaling or protein fouling. However, the molecular-level dynamics of silica binding to proteins and the resulting structural changes in both proteins and silica remain poorly understood. This study investigates the complexation process between silica and proteins-negatively charged bovine serum albumin (BSA) and positively charged lysozyme (LYZ) at neutral pH-using infrared spectroscopy (IR), in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and multiple computational simulations. The findings reveal that both protein and silica structures undergo changes during the complexation process, with calcium ions in the solution significantly exacerbating these alterations. In particular, in situ ATR-FTIR combined with two-dimensional correlation spectroscopy analysis shows that BSA experiences more pronounced unfolding, providing additional binding sites for silica adsorption compared to LYZ. The adsorbed proteins promote silica polymerization from lower-polymerized to higher-polymerized species. Furthermore, molecular dynamics simulations demonstrate greater conformational variation in BSA through root-mean-square-deviation analysis and the bridging role of calcium ions via mean square displacement analysis. Molecular docking and density functional theory calculations identify the binding sites and energy of silica on proteins. In summary, this research offers a comprehensive understanding of the protein-silica complexation process, contributing to the knowledge of synergistic behaviors of inorganic scaling and organic fouling on membrane surfaces. The integrated approach used here may also be applicable for exploring other complex complexation processes in various environments.


Calcium , Silicon Dioxide , Molecular Docking Simulation , Serum Albumin, Bovine/chemistry , Spectroscopy, Fourier Transform Infrared , Ions , Adsorption
7.
Adv Mater ; : e2305924, 2023 Sep 12.
Article En | MEDLINE | ID: mdl-37698463

Utilizing renewable biomass as a substitute for fossil resources to produce high-value chemicals with a low carbon footprint is an effective strategy for achieving a carbon-neutral society. Production of chemicals via single-atom catalysis is an attractive proposition due to its remarkable selectivity and high atomic efficiency. In this work, a supramolecular-controlled pyrolysis strategy is employed to fabricate a palladium single-atom (Pd1 /BNC) catalyst with B-doped Pd-Nx atomic configuration. Owing to the meticulously tailored local coordination microenvironment, the as-synthesized Pd1 /BNC catalyst exhibits remarkable conversion capability for a wide range of biomass-derived aldehydes/ketones. Thorough characterizations and density functional theory calculations reveal that the highly polar metal-N-B site, formed between the central Pd single atom and its adjacent N and B atoms, promotes hydrogen activation from the donor (reductants) and hydrogen transfer to the acceptor (C═O group), consequently leading to exceptional selectivity. This system can be further extended to directly synthesize various aromatic and furonic amines from renewable lignocellulosic biomass, with their greenhouse gas emission potentials being negative in comparison to those of fossil-fuel resource-based amines. This research presents a highly effective and sustainable methodology for constructing C─N bonds, enabling the production of a diverse array of amines from carbon-neutral biomass resources.

8.
Nat Commun ; 14(1): 5134, 2023 Aug 23.
Article En | MEDLINE | ID: mdl-37612275

Electrochemical technology is a robust approach to removing toxic and persistent chlorinated organic pollutants from water; however, it remains a challenge to design electrocatalysts with high activity and selectivity as elaborately as natural reductive dehalogenases. Here we report the design of high-performance electrocatalysts toward water dechlorination by mimicking the binding pocket configuration and catalytic center of reductive dehalogenases. Specifically, our designed electrocatalyst is an assembled heterostructure by sandwiching a molecular catalyst into the interlayers of two-dimensional graphene oxide. The electrocatalyst exhibits excellent dechlorination performance, which enhances reduction of intermediate dichloroacetic acid by 7.8 folds against that without sandwich configuration and can selectively generate monochloro-groups from trichloro-groups. Molecular simulations suggest that the sandwiched inner space plays an essential role in tuning solvation shell, altering protonation state and facilitating carbon-chlorine bond cleavage. This work demonstrates the concept of mimicking natural reductive dehalogenases toward the sustainable treatment of organohalogen-contaminated water and wastewater.

9.
Adv Sci (Weinh) ; 10(29): e2302670, 2023 10.
Article En | MEDLINE | ID: mdl-37587775

Electroactive microbial cells have evolved unique extracellular electron transfer to conduct the reactions via redox outer-membrane (OM) proteins. However, the electron transfer mechanism at the interface of OM proteins and nanomaterial remains unclear. In this study, the mechanism for the electron transfer at biological/inorganic interface is investigated by integrating molecular modeling with electrochemical and spectroscopic measurements. For this purpose, a model system composed of OmcA, a typical OM protein, and the hexagonal tungsten trioxide (h-WO3 ) with good biocompatibility is selected. The interfacial electron transfer is dependent mainly on the special molecular configuration of OmcA and the microenvironment of the solvent exposed active center. Also, the apparent electron transfer rate can be tuned by site-directed mutagenesis at the axial ligand of the active center. Furthermore, the equilibrium state of the OmcA/h-WO3 systems suggests that their attachment is attributed to the limited number of residues. The electrochemical analysis of OmcA and its variants reveals that the wild type exhibits the fastest electron transfer rate, and the transient absorption spectroscopy further shows that the axial histidine plays an important role in the interfacial electron transfer process. This study provides a useful approach to promote the site-directed mutagenesis and nanomaterial design for bioelectrocatalytic applications.


Heme , Shewanella , Heme/chemistry , Heme/metabolism , Electrons , Bacterial Outer Membrane Proteins/chemistry , Bacterial Outer Membrane Proteins/metabolism , Shewanella/metabolism , Cytochromes/metabolism , Oxides
10.
Proc Natl Acad Sci U S A ; 120(20): e2302407120, 2023 May 16.
Article En | MEDLINE | ID: mdl-37155859

Clarifying the reaction pathways at the solid-water interface and in bulk water solution is of great significance for the design of heterogeneous catalysts for selective oxidation of organic pollutants. However, achieving this goal is daunting because of the intricate interfacial reactions at the catalyst surface. Herein, we unravel the origin of the organic oxidation reactions with metal oxide catalysts, revealing that the radical-based advanced oxidation processes (AOPs) prevail in bulk water but not on the solid catalyst surfaces. We show that such differing reaction pathways widely exist in various chemical oxidation (e.g., high-valent Mn3+ and MnOX) and Fenton and Fenton-like catalytic oxidation (e.g., Fe2+ and FeOCl catalyzing H2O2, Co2+ and Co3O4 catalyzing persulfate) systems. Compared with the radical-based degradation and polymerization pathways of one-electron indirect AOP in homogeneous reactions, the heterogeneous catalysts provide unique surface properties to trigger surface-dependent coupling and polymerization pathways of a two-electron direct oxidative transfer process. These findings provide a fundamental understanding of catalytic organic oxidation processes at the solid-water interface, which could guide the design of heterogeneous nanocatalysts.

11.
Water Res X ; 19: 100182, 2023 May 01.
Article En | MEDLINE | ID: mdl-37215310

Capacitive deionization (CDI) is a promising technique for brackish water desalination. However, its salt electrosorption capacity is insufficient for practical application yet, and little information is available on hardness ion (Mg2+, Ca2+) removal in CDI. Herein, hierarchical porous carbon (HPC) was prepared from low-cost and renewable microalgae via a simple one-pot approach, and both MnO2/HPC and polyaniline/HPC (PANI/HPC) composites were then synthesized using a facile, one-step hydrothermal method. Compared with the MnO2 electrode, the MnO2/HPC electrode presented an improved hydrophilicity, higher specific capacitance, and lower electrode resistance. The electrodes exhibited pseudocapacitive behaviors, and the maximum salt electrosorption capacities of MnO2/HPC-PANI/HPC CDI cell was up to 0.65 mmol g-1 NaCl, 0.71 mmol g-1 MgCl2, and 0.76 mmol g-1 CaCl2, respectively, which were comparable and even higher than those of the previously reported CDI cells. Additionally, the MnO2/HPC electrode presented a selectivity order of Ca2+ ≥ Mg2+ > Na+, and the divalent cation selectivity was found to be attributed to their stronger binding strength in the cavity of MnO2. Multiscale simulations further reveal that the MnO2/HPC electrodes with the unique luminal configuration of MnO2 and HPC as supportive framework could offer a great intercalation selectivity of the divalent cations and exhibit a great promise in hardness ion removal.

12.
Proc Natl Acad Sci U S A ; 120(6): e2215305120, 2023 Feb 07.
Article En | MEDLINE | ID: mdl-36730199

Photosynthesis of hydrogen peroxide (H2O2) by selective oxygen reduction is a green and cost-effective alternative to the energy-intensive anthraquinone process. Although inexpensive polymeric graphitic carbon nitride (g-C3N4) exhibits the ability to produce H2O2, its disordered and amorphous structure leads to a high recombination rate of photogenerated carriers and hinders charge transfer between layers. Herein, we predict that stacked polymeric g-C3N4 with ion intercalation (K+ and I-) can improve carrier separation and transfer by multiscale computational simulations. The electronic structures of g-C3N4 were tailored and modified by intercalating K+ and I- into the layer-by-layer structures. Guided by the computational predictions, we achieved efficient solar-driven H2O2 production by employing this facile and ion-intercalated crystalline g-C3N4. An H2O2 production rate of 13.1 mM g-1 h-1 and an apparent quantum yield of 23.6% at 400 nm were obtained. The synergistic effects of crystallinity regulation and dual interstitial doping engineering triggered the formation of new light absorption centers, the establishment of rapid charge diffusion channels, and the enhancement of two-electron oxygen reduction characteristics. This work sheds light on the dual tuning of crystallinity and electronic structure and broadens the design principles of organic-conjugated polymer photocatalysts for environmental remediation and energy conservation.

13.
Nat Commun ; 13(1): 7869, 2022 Dec 22.
Article En | MEDLINE | ID: mdl-36550149

Studying the localized electrocatalytic activity of heterogeneous electrocatalysts is crucial for understanding electrocatalytic reactions and further improving their performance. However, correlating the electrocatalytic activity with the microscopic structure of two-dimensional (2D) electrocatalysts remains a great challenge due to the lack of in situ imaging techniques and methods of tuning structures with atomic precision. Here, we present a general method of probing the layer-dependent electrocatalytic activity of 2D materials in situ using a plasmonic imaging technique. Unlike the existing methods, this approach was used to visualize the surface charge density and electrocatalytic activity of single 2D MoS2 nanosheets, enabling the correlation of layer-dependent electrocatalytic activity with the surface charge density of single MoS2 nanosheets. This work provides insights into the electrocatalytic mechanisms of 2D transition metal dichalcogenides, and our approach can serve as a promising platform for investigating electrocatalytic reactions at the heterogeneous interface, thus guiding the rational design of high-performance electrocatalysts.

14.
Adv Mater ; 34(31): e2202891, 2022 Aug.
Article En | MEDLINE | ID: mdl-35679161

Single-atom catalysts have emerged as an efficient oxidant activator for eliminating organic pollutants in Fenton-like systems. However, the complex preparation, single active site, lack of understanding of the fundamental mechanism, and harsh pH conditions currently limit their practical applications. In this work, single-atom iron anchored nitrogen-rich g-C3 N4 nanotubes (FeCNs) are designed and synthesized by a facile approach, and eco-friendly peracetic acid (PAA) is selected as the oxidant for Fenton-like reactions. The constructed heterogenous system achieves an enhanced degradation of various organic contaminants over a wide pH range of 3.0-9.0, exhibiting an ultrahigh and stable catalytic activity, outperforming equivalent quantities of pristine g-C3 N4 by 75 times. The 18 O isotope-labeling technique, probe method, and theoretical calculations demonstrate that the efficient catalytic activity relies on the high-valency iron-oxo species coupled with organic radicals generated by PAA. An increase in electron transport from the contaminant to the formed "metastable PAA/FeCN catalyst surface complex" is detected. A double driving mechanism for the tubular g-C3 N4 regulated by a single Fe site and PAA activation is proposed. This work opens an avenue for developing novel catalysts with the coexistence of multiple active units and providing opportunities for significantly improving catalytic efficiency.

15.
Nat Commun ; 13(1): 3005, 2022 05 30.
Article En | MEDLINE | ID: mdl-35637224

Removal of organic micropollutants from water through advanced oxidation processes (AOPs) is hampered by the excessive input of energy and/or chemicals as well as the large amounts of residuals resulting from incomplete mineralization. Herein, we report a new water purification paradigm, the direct oxidative transfer process (DOTP), which enables complete, highly efficient decontamination at very low dosage of oxidants. DOTP differs fundamentally from AOPs and adsorption in its pollutant removal behavior and mechanisms. In DOTP, the nanocatalyst can interact with persulfate to activate the pollutants by lowering their reductive potential energy, which triggers a non-decomposing oxidative transfer of pollutants from the bulk solution to the nanocatalyst surface. By leveraging the activation, stabilization, and accumulation functions of the heterogeneous catalyst, the DOTP can occur spontaneously on the nanocatalyst surface to enable complete removal of pollutants. The process is found to occur for diverse pollutants, oxidants, and nanocatalysts, including various low-cost catalysts. Significantly, DOTP requires no external energy input, has low oxidant consumption, produces no residual byproducts, and performs robustly in real environmental matrices. These favorable features render DOTP an extremely promising nanotechnology platform for water purification.


Environmental Pollutants , Water Pollutants, Chemical , Decontamination , Oxidants , Water
16.
Front Bioeng Biotechnol ; 9: 705414, 2021.
Article En | MEDLINE | ID: mdl-34447742

Bioelectrochemical systems (BESs) are emerging as attractive routes for sustainable energy generation, environmental remediation, bio-based chemical production and beyond. Electron shuttles (ESs) can be reversibly oxidized and reduced among multiple redox reactions, thereby assisting extracellular electron transfer (EET) process in BESs. Here, we explored the effects of 14 ESs on EET in Shewanella oneidensis MR-1, and found that anthraquinone-2-sulfonate (AQS) led to the highest cathodic current density, total charge production and reduction product formation. Subsequently, we showed that the introduction of -OH or -NH2 group into AQS at position one obviously affected redox potentials. The AQS-1-NH2 exhibited a lower redox potential and a higher Coulombic efficiency compared to AQS, revealing that the ESs with a more negative potential are conducive to minimize energy losses and improve the reduction of electron acceptor. Additionally, the cytochromes MtrA and MtrB were required for optimal AQS-mediated EET of S. oneidensis MR-1. This study will provide new clues for rational design of efficient ESs in microbial electrosynthesis.

17.
Environ Sci Technol ; 2021 Jul 28.
Article En | MEDLINE | ID: mdl-34319703

The biogeochemical cycle of iron is of great importance to living organisms on Earth, and dissimilatory metal-reducing bacteria (DMRB) with the capability of reducing hematite (α-Fe2O3) by outer-membrane (OM) cytochromes play a great role in the iron cycle. However, the dynamic binding of cytochromes to α-Fe2O3 at the molecular level and the resulting impact on the photon-to-electron conversion of α-Fe2O3 for the iron cycle are not fully understood. To address these issues, two-dimensional IR correlation analysis coupled with molecular dynamics (MD) simulations was conducted for an OmcA-Fe2O3 system as OmcA bonds stronger with hematite in a typical DMRB,Shewanella. The photoelectric response of α-Fe2O3 with the OmcA coating was evaluated at three different potentials. Specifically, the binding groups from OmcA to α-Fe2O3 were in the sequence of carboxyl groups, amide II, and amide I. Further MD analysis reveals that both electrostatic interactions and hydrogen bonds played essential roles in the binding process, leading to the structural changes of OmcA to facilitate iron reduction. Moreover, the OmcA coating could store the photogenerated electrons from α-Fe2O3 like a capacitor and utilize the stored electrons for α-Fe2O3 reduction in dark and anoxic environments, further driving the biogeochemical cycle of iron. These investigations give the dynamic information on the OM protein/hematite interaction and provide fundamental insights into the biogeochemical cycle of iron by taking the photon-induced redox chemistry of iron oxide into consideration.

18.
Environ Sci Technol ; 55(11): 7531-7540, 2021 06 01.
Article En | MEDLINE | ID: mdl-33974407

Cadmium ion (Cd2+) is a common environmental pollutant with high biotoxicity. Interestingly, the Cd2+ biotoxicity can be alleviated by the coexisting selenite (SeO32-), which induces the formation of cadmium selenide-rich nanoparticles (CdSe NPs) under the function of thiol-capping peptides. However, the detailed biochemical mechanisms by which Cd and Se are synergistically transformed into CdSe NPs in living organisms remain unclear so far. Here, we shed light on the molecular basis of such biotransformation processes in Caenorhabditis elegans by focusing on the roles of several key thiol-capping peptides. By monitoring the compositional and structural changes of the Cd and Se species and the genetic-level responses of nematodes, we revealed the specific roles of glutathione (GSH) and phytochelatins (PCs) in mediating the CdSe NP formation. With the aid of in vitro bioassembly assay and density functional theory calculations, the detailed Cd-Se interaction pathways were further deciphered: the ingested Cd binds predominantly to GSH and PCs in sequence, then further interacts with selenocysteine to form tetrahedral-structured PC2-Cd2-Sec2 complex, and ultimately grows into CdSe NPs. This work provides molecular-level insights into the Cd-Se interaction in C. elegans and lays a basis for controlling the ecological and health risks of heavy metals in polluted environment.


Cadmium , Selenium , Animals , Biotransformation , Caenorhabditis elegans , Glutathione/metabolism , Phytochelatins/metabolism , Sulfhydryl Compounds
19.
Nat Commun ; 12(1): 303, 2021 01 12.
Article En | MEDLINE | ID: mdl-33436610

The construction of enzyme-inspired artificial catalysts with enzyme-like active sites and microenvironment remains a great challenge. Herein, we report a single-atomic-site Co catalyst supported by carbon doped boron nitride (BCN) with locally polarized B-N bonds (Co SAs/BCN) to simulate the reductive dehalogenases. Density functional theory analysis suggests that the BCN supports, featured with ionic characteristics, provide additional electric field effect compared with graphitic carbon or N-doped carbon (CN), which could facilitate the adsorption of polarized organochlorides. Consistent with the theoretical results, the Co SAs/BCN catalyst delivers a high activity with nearly complete dechlorination (~98%) at a potential of -0.9 V versus Ag/AgCl for chloramphenicol (CAP), showing that the rate constant (k) contributed by unit mass of metal (k/ratio) is 4 and 19 times more active than those of the Co SAs/CN and state-of-the-art Pd/C catalyst, respectively. We show that Co single atoms coupled with BCN host exhibit high stability and selectivity in CAP dechlorination and suppress the competing hydrogen evolution reaction, endowing the Co SAs/BCN as a candidate for sustainable conversion of organic chloride.

20.
Water Res ; 191: 116799, 2021 Mar 01.
Article En | MEDLINE | ID: mdl-33453457

Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) for wastewater treatment have recently attracted widespread interests. However, the degradation of organic pollutants via traditional radical-dominated pathway is severely limited by the side reactions between radicals and the co-existing inorganic anions, especially under high salinity conditions. Herein, an efficient Fe/O co-doped g-C3N4nanosheet catalyst was synthesized to dominantly activate PMS through a dual non-radical pathway with the singlet oxygen and high-valent iron-oxo species (Fe(V)=O). The rapid degradation of model pollutant bisphenol A (BPA) was achieved by dosing PMS (1 mM), catalyst (0.1 g/L) in a simulated high-salt wastewater (≥200 mM) of the developed Fe/O-doped g-C3N4+PMS system with a reaction rate constant of 1204-fold higher than that in g-C3N4+PMS system. The O and Fe co-dopants could reconfigurate the electronic structure of pristine g-C3N4 to produce more non-radical active species. The formed Fe(V)=O played a main role in the BPA degradation by promoting electron transfer from BPA molecule to the "metastable PMS/catalyst complex", which was verified by electrochemical tests and density functional theory calculations. The auxiliary transient productions of ·OH+SO4·- species were also favorable for the pollutant degradation. Excellent reusability in a wide pH range confirmed the practical application prospects of the Fe/O-doped g-C3N4+PMS system. The successive addition of PMS with a low dosage into the system rich in pollutants was confirmed to favor the PMS utilization. Our work unveils the potential applications of a non-radical dominated process for the decontamination of organic pollutants in saline water.


Environmental Pollutants , Decontamination , Peroxides , Salinity
...