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Solid sodium ion batteries (SIBs) show a significant amount of potential for development as energy storage systems; therefore, there is an urgent need to explore an efficient solid electrolyte for SIBs. Na3Zr2Si2PO12 (NZSP) is regarded as one of the most potential solid-state electrolytes (SSE) for SIBs, with good thermal stability and mechanical properties. However, NZSP has low room temperature ionic conductivity and large interfacial impedance. F−doped NZSP has a larger grain size and density, which is beneficial for acquiring higher ionic conductivity, and the composite system prepared with epoxy can further improve density and inhibit Na dendrite growth. The composite system exhibits an outstanding Na+ conductivity of 0.67 mS cm−1 at room temperature and an ionic mobility number of 0.79. It also has a wider electrochemical stability window and cycling stability.

A comprehensive evaluation of the different design strategies and development potentials of solid-state electrolytes based on covalent organic frameworks has been carried out through analysis of their electrochemical properties and applicability.

Limiting the shuttle effect of polysulfides is an important means to realizing high energy density lithium–sulfur batteries (Li–S).

Along with the continuous consumption in lithium-ion batteries (LIBs), the price of cobalt is inevitably going up in recent years. Therefore, recycling valuable Co element from spent devices, and boosting its service efficiency are becoming two indispensable approaches to promote the utilization of Co in various energy conversion/storage devices. Herein, we realize the recovery of Co from spent LIBs and synthesize a three–dimensional (3D) sea-urchin-like cobalt nitride composite material (labeled as CoN-Gr-2), which is used as a bi-functional catalyst for water splitting. Benefiting from the intrinsic high conductivity, larger surface area and unique 3D sea–urchin–like architecture, CoN-Gr-2 shows an excellent electron transfer efficiency, highly exposed active sites as well as the superior mass transport capacity. The CoN-Gr-2 catalyst exhibits low overpotentials of 128.9 mV and 280 mV for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), which are comparable to the commercial 20 wt% Pt/C and RuO2 catalysts. Moreover, when adopting CoN-Gr-2 as both anode and cathode materials for overall water splitting (in 1.0 M KOH electrolyte), the assembled cell achieves a current density of 10 mA cm−2 at 1.61 V, which almost close to that of Pt/C||RuO2 benchmark (1.60 V), demonstrating its superior water-splitting efficiency. Meanwhile, the CoN catalysts exhibit strong chemical interaction with the Gr support, suppressing the aggregation of CoN catalysts and maintains their high activity during HER and OER reactions. So, the cell exhibits a high current retention of 97.3% after 40 h. This work successfully develops an industrial chain from recycling Co wastes in spent energy devices to controllably designing 3D sea-urchin-like CoN-Gr with high water splitting efficiency. Therefore, it could further promote the efficient utilization of valuable Co element in various energy devices.

The high theoretical energy density and low cost make lithium-sulfur (Li-S) batteries an ideal choice for next-generation energy storage devices. However, the slow kinetics cause the reaction process to be incomplete and low reaction rate. To solve this problem, a novel cooperative catalytic interface with fine molecular regulation mechanism is designed by taking advantage of the electronic correlation between the catalyst and polysulfides (LiPSs), which multi-step process contains chemical adsorption, catalytic activity center and lithium-ion transfer. The cooperative catalytic interface greatly accelerates the kinetics of LiPSs conversion, precipitation of Li2S in discharging, and insoluble Li2S decomposition in charging process. Therefore, the PdNi@ND-C3N4-based cathode exhibits an outstanding electrochemical performance. Even under the condition of high sulfur loading of 6.0 mg cm−2, the constructed Li-S batteries demonstrate the ultralow capacity decay rate of 0.025% per cycle up to 1000 cycles. Moreover, its catalytic mechanism is deeply analyzed through DFT theory and in(ex)-situ technologies. This work will open a new window for the rational design of Li-S electrocatalyst based on cooperative interface.

The conversion of CO2 into CO, CH4 and other hydrocarbons through solar energy can alleviate the energy shortage problem. We design a novel photocatalyst with S defects CuIn5S8@MoSe2 hollow structure. The interlayer-expanded MoSe2 can increase the adsorption of intermediates. The unique hollow structure can improve the light utilization efficiency and the electron–holes separation. CuIn5S8 with S vacancies in bimetallic sites has high selectivity and photocatalytic reduction of CO2 activity. Therefore, S vacant CuIn5S8 confined in a few-layers MoSe2 with interlayer-expanded hollow heterostructures exhibit super performance for photocatalytic CO2 reduction. After 8-h light reaction, the outputs of CO and CH4 for the 15.3 wt% CuIn5S8@MoSe2 sample containing S vacancies (Vs) are 30.4 and 14.7 µmol·g−1, respectively. The mechanism is also investigated in detail through in situ Fourier transform infrared spectroscopy technology.

To deal with the relatively low HER catalysis efficiencies of existing cobalt nitride (CoN) catalysts, it is highly desirable to design new types of CoN catalysts to realize high-efficiency water splitting. Herein, by using simple hydrothermal and nitridation methods, we realize the synthesis of novel three-dimensional (3D) flower-like CoN (CoN-F), CoN porous spheres (CoN-S), and polyhedral CoN (CoN-P) via utilizing various weak bases. Benefiting from a much larger surface area and a unique 3D flower-like architecture (consisting of 2D porous CoN nanosheets), the CoN-F catalyst shows highly exposed active sites and superior mass/electron transfer abilities. Naturally, the CoN-F catalyst exhibits more outstanding hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic performance than either CoN-P or CoN-S. In order to achieve a current density of 10 mA cm−2, 3D flower-like CoN-F needs only low overpotentials of 191.7 mV and 276.2 mV for the HER and OER, respectively. Furthermore, upon using the 3D flower-like CoN-F catalyst as both the anode and cathode material in a two-electrode overall water-splitting cell, the corresponding (−)CoN-F‖CoN-F(+) cell achieves a current density of 10 mA cm−2 at 1.613 V in 1.0 M KOH, which is just 10 mV larger than a (−)Pt/C‖RuO2(+) cell (1.592 V). It outperforms most existing non-precious-metal electrocatalysts, demonstrating superior water-splitting efficiency. In addition, the 3D flower-like CoN-F catalyst shows excellent stability during the alkaline HER and OER, and full water splitting. This work successfully opens a new pathway for boosting the HER/OER electrocatalytic abilities of CoN catalysts through structural design, which may promote the efficient utilization of metal nitrides in various energy storage and conversion devices.

In this study, we constructed a highly sensitive and selective electrochemical sensing strategy for l-ascorbic acid (AA) based on a covalent organic framework (COF)-loading non-noble transition metal Co ion and macrocyclic cationic pillar[6]arene (CP6) nanocomposite (CP6-COF-Co). The COF plays a crucial role in anchoring the Co ion according to its crystalline porous and multiple coordination sites and has an outstanding performance for building an electrochemical sensing platform based on a unique two-dimensional structure. Accordingly, the transition-metal Co ion can be successfully anchored on the framework of COF and shows strong catalytic activity for the determination of AA. Moreover, introduction of host-guest recognition based on CP6 and AA can bring new properties for enhancing selectivity, sensitivity, and practical application in real environment. Host-guest interactions between CP6 and AA were evaluated by the 1H NMR spectrum. When compared with other literatures, our method displayed a lower determination limit and broader linear range. To the best of our knowledge, this is the first study carried out for the non-noble transition-metal Co ion, COF, and pillar[6]arene hybrid material in sensing field, which has a potential value in sensing, catalysis, and preparation of advanced multifunction materials.

Organic electrode materials play a crucial role in environmentally friendly and sustainable lithium-ion batteries (LIBs) due to their abundance, high theoretical capacity, inexpensiveness, and recy...

Phosphorus-based materials can be used to construct promising anodes for sodium-ion batteries (SIBs) due to their high theoretical capacity (2596 mA h g−1) and safe working potential. However, their disadvantages are severe volume changes as well as poor electronic conductivity (10−14 S cm−1), resulting in fast capacity decay during cycling. To find solutions to the aforementioned issues, in this work, self-assembled nanosheets were used to synthesize hierarchical hollow spherical Co9S8. The unique hierarchical hollow spherical structures provide more active sites, which accommodate the volume change and effectively improve the conductivity. Amorphous red P was encapsulated in the hierarchical hollow spherical Co9S8 and formed a P@Co9S8 anode. Moreover, the introduction of red P via an evaporation–condensation method led to the effective surface modification of Co9S8 and thus further improved the conductivity of the hollow P@Co9S8 hybrid anode. The unique structure of SIBs assembled with the P@Co9S8 anode alleviated volume change and enabled fast electron transport, and excellent cycling stability and outstanding rate capability were exhibited, retaining a high discharge capacity of 551.7 mA h g−1 after 1000 cycles at 1 A g−1 and maintaining coulombic efficiencies greater than 98.2%. Furthermore, the sodium-ion storage mechanism of P@Co9S8 was dynamically investigated, providing a new perspective for determining the electrochemical cycling behavior.

NASICON-type Na

Limiting the shuttle effect of polysulfides is an important means to realizing high energy density lithium-sulfur batteries (Li-S). In this study, an efficient electrocatalyst (CNFs@Ni

In this study, a class of supramolecular host water-soluble pillar[6]arene (WP6)-modified Ag nanoparticle (WP6@Ag)-functionalized two-dimensional (2D) covalent organic framework (COF) composite is ...

A multicomponent functionalized nano-material (Au@CP5@MoS2) is prepared by control assembly of Au nanoparticles on the surface of CP5@MoS2 for sensing and catalysis reduction of toxic explosives p-dinitrobenzene (p-DNB). Firstly, the Au nanoparticles are obtained by a green redox reaction between HAuCl4 and hydroxylatopillar[5]arene (HP5) in the presence of a small amount of hydroxide ion without any harsh reduced agent. The CP5@MoS2 is prepared by a rapidly supramolecule mediated hydrothermal route in the presence of aqueous solution of cationic pillar[5]arene (CP5). Therefore, we construct an electrochemical sensing platform for the high sensitive and selective determination of p-DNB based on the excellent supramolecular recognition of CP5/HP5 and the high catalytic activity of Au nanoparticles. Moreover, the p-DNB can be reduced into 1,4-diaminobenzene by NaBH4 in the presence of the prepared Au@CP5@MoS2, which can reduce the explosion dangerousness of p-DNB to some extent. This strategy might present a prospective value in sensing and reducing toxic explosives.

We developed a green and facile approach for synthesizing Ag@PP6@SWCNT nano-material via in-situ loading silver nanoparticles on the surface of phosphate pillar [6]arene (PP6) functionalized single-walled carbon nanotubes (SWCNT) at room temperature and without using either toxic or organic solvents. Ag nanoparticles (with an average size of 3–4 nm) were uniformly dispersed on the surface of SWCNT via the anchoring effect of PP6. PP6 provided a coordination environment between Ag and –PO 3 2– groups in PP6, and there were the π-π interactions between SWCNT and benzene rings of PP6. The obtained hybrid nano-material Ag@PP6@SWCNT was characterized using UV-vis absorption spectrum, transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Compared to commercial Pd/C and Ag@SWCNT catalysts, Ag@PP6@SWCNT exhibited higher catalytic activity for 4-nitrophenol (4-NP) reduction and methylene blue (MB) degradation, respectively. Moreover, because of the excellent supramolecular host-guest recognition capability of PP6, a sensitive and convenient electrochemical sensing platform for detecting paraquat (PQ) was constructed, and had potential applications in sensing highly toxic herbicides.

A facile and clean strategy is developed here to synthesize the Au@HP5@SWCNT nanocomposite via in-site loading of Au nanoparticles onto the surface of hydroxyl pillar[5]arene (HP5) functionalized single-walled carbon nanotubes (SWCNT). The process is achieved by π–π stacking and the coordination effect at room temperature, which avoids using toxic chemicals such as N2H4, NaBH4, and organic solvent. The Au nanoparticles with an average size of ∼10 nm are dispersed on the surface of SWCNT by the anchoring effect of HP5 that provides the coordination role between Au and the hydroxyl oxygen in HP5, and by the π–π interaction between SWCNT and the benzene rings of HP5. The obtained hybrid nanomaterial Au@HP5@SWCNT has shown high catalytic activity for the ethanol oxidation reaction (EOR), due to the small sized Au nanoparticles, and the sensitive sensing performance for p-dinitrobenzene (p-DNB) based on the excellent supramolecular host–guest recognition capability of HP5. This nanomaterial, Au@HP5@SWCNT, exhibits preeminent catalysis and sensing properties compared with others including SWCNT, Au@HP5, and HP5@SWCNT, and so has potential value in catalyzing, sensing, and in other fields.

While numerous sensing strategies have been applied in the determination of Acetaminophen (AP), dopamine (DA), and ascorbic acid (AA), the selectivity is always a critical challenge based on their similar structure and function. Accordingly, the development of a highly selective sensing method is not only necessary but also crucial. In this study, a novel electrochemical sensing platform for the simultaneous determination of AP and DA has been successfully constructed based on a multifunctional nanocomposite (WP6-Pd-COF) of water-soluble pillar[6]arene (WP6), ultrafine Pd nanoparticles, and triethylene glycol-modified covalent organic framework (COF). Pd nanoparticles with an average size of 4.2 nm are prepared by reducing K2PdCl4 under the stabilization of oxygen-rich COF, which shows superior catalytic activity in electrochemical detection. A supramolecular host-guest recognition system introduced between WP6 and analytes (AP, DA, and AA) can effectively recognize AP and DA, implying the simultaneous determination of AP and DA by this approach. The electrode, best operated at a working potential range from -0.2 to 0.8 V (vs. Hg/Hg2Cl2), works in the concentration ranges of 0.2-8 μM for DA and 0.1-7.5 μM for AP, and has a detection limit of 0.06 μM for DA and 0.03 μM for AP (S/N = 3). Therefore, this study presents potential application values in sensing, catalysis, and other fields.

Solid-state sodium-ion batteries exhibit a great promising opportunity for the future energy storage, and thus exploring a high-efficiency sodium-ion conductor is the urgent challenge. Covalent organic frameworks (COFs) have accurately directional and well-defined ion channels and are a promising and optimal platform for solid-state Na-ion conductor. In this work, we study the first example of carboxylic acid sodium functionalized polyarylether linked COF (denoted as NaOOC-COF) as an advanced Na-ion quasi-solid-state conductor film. Benefiting from the well-defined ion channels, the functionalized NaOOC-COF exhibits an outstanding Na+ conductivity of 2.68×10−4 S cm−1 at room temperature, low activation energy (Ea) with 0.24 eV and high transference number of 0.9. Particularly, the NaOOC-COF shows long-time cycling performance in the assembled quasi-solid-state battery, and can restrain dendrite growth through interface regulation. Furthermore, the Na+ diffusion mechanism in whole-cell system is investigated thoroughly. Such extraordinary Na-ion transport result based on COFs is achieved for the first time. This novel strategy may exploit the new area of Na-ion quasi-solid-state electrolytic devices, and simultaneously accelerate the progress of functionalized COFs.

Iron phthalocyanine (FePc) with unique iron-pyrrolic nitrogen (Fe-N) structure has attracted an increasing attention on the oxygen reduction reaction (ORR). Unfortunately, the Fe-N site is not “active” because of its symmetry in the plane and always exhibits unsatisfactory ORR activity. Herein, we design a non-contact scheme of axial carbon substrate induced Fe-N electron localization to improve its ORR performance. Theoretical calculation indicates that the addition of MWCNTs causes the aggregation of electron cloud around Fe-N, enhances the oxygen adsorption capacity and accelerates the ORR rate. The obtained catalyst shows a Tafel slope of 35.8 mV·dec−1, an initial potential of 0.979 V vs. RHE, a half-wave potential of 0.902 V vs. RHE and a limiting current density of 5.42 mA·cm−2 in alkaline medium. The Zn-air battery assembled by this catalyst also demonstrates a large discharge voltage of 1.296 V, considerable power density of 102 mW·cm−2 and superior cycling stability (500 cycles). This work not only simplifies the process of preparing high efficiency transition metal catalysts but also does some tentative explore for realizing the practical use of Zn-air battery.

The rational design of electrochemical methods for isomer recognition is a focus of research in the molecular recognition and separation fields. In this work, a novel, rapid, and convenient electrochemical approach for recognition of nitrophenol isomers was constructed based on the alternating layer-by-layer (LbL) assembly of water-soluble cationic and anionic pillar [5]arene on a carboxylic graphene (C-Gra) modified glass carbon electrode. The electrochemical recognition of nitrophenol isomers was investigated by differential pulse voltammetry (DPV). The electrochemical results reveal that both the peak currents of m-nitrophenol (m-NP) and p-nitrophenol (p-NP) increased with the increasing of the layer number of the assembled pillar [5]arene, whereas the peak current of o-nitrophenol (o-NP) decreased with the increased layers, which demonstrated an efficient route for discriminating the nitrophenol isomers. The molecular recognition mechanism was studied by 1H NMR spectra, which indicated that the m-NP and p-NP can be included in the cavity of the pillar [5]arene host. However, the o-NP could not enter into the host of pillar [5]arene, which was ascribed to the formation of intramolecular hydrogen bond of o-NP. The LbL assembly modified GCE was used for detecting p-NP and m-NP. A low detection limit of 0.33 μM (S/N = 3) and a linear response range of 1–90 μM for p-NP were obtained by using this method. And the detection limit of 0.16 μM (S/N = 3) and a linear response range of 0.5–70 μM for m-NP were obtained. This method of LbL assembly modified GCE has potential application in molecular recognition and separation.

The rational design of electrochemical methods for chiral recognition is a focus of research in the detection fields of biomolecules and pharmaceuticals. In this work, a novel, rapid, and convenient electrochemical approach for recognition of tryptophan isomers (L-/D-Trp) was constructed based on the alternating layer-by-layer assembly of water-soluble cationic and anionic pillar[5]arene on a carboxylic graphene (C-Gra) modified glass carbon electrode. Differential pulse voltammetry (DPV) was employed to study the electrochemical recognition of tryptophan isomers. The results reveal that both the peak currents of L-Trp and D-Trp decreased with the increasing of the layer number of the assembled pillar[5]arene, whereas the peak current value's difference between the L-Trp and D-Trp increased with the increased layers, which demonstrated an efficient route for discriminating the L-Trp and D-Trp. The recognition mechanism was studied by 1H NMR spectra and molecular docking. The host−guest interaction is different for D- and L-Trp due to the opposite steric configurations of the Trp isomers, resulting in significantly discernible electrochemical differences in both peak currents and consequently effective chiral recognition of Trp isomers. This study is the first example that shows the construction of electrochemical chiral separation platform based on pillar[5]arene. This method shows potential applications in many fields, including separation, purification, storage of chiral molecule, drug detection and analysis.

Prostate specific antigen (PSA) is the most significant biomarker for the screening of prostate cancer in human serum. However, most methods for the detection of PSA often require major laboratories, precisely analytical instruments and complicated operations. Currently, the design and development of satisfying electrochemical biosensors based on biomimetic materials (e.g. synthetic receptors) and nanotechnology is highly desired. Thus, we focused on the combination of molecular recognition and versatile nanomaterials in electrochemical devices for advancing their analytical performance and robustness. Herein, by using the present prepared multifunctional hydroxyl pillar[5]arene@gold nanoparticles@graphitic carbon nitride (HP5@AuNPs@g–C3N4) hybrid nanomaterial as robust biomimetic element, a high-performance electrochemical immunosensor for detection of PSA was constructed. The as-prepared immunosensor, with typically competitive advantages of low cost, simple preparation and fast detection, exhibited remarkable robustness, ultra-sensitivity, excellent selectivity and reproducibility. The limit of detection (LOD) and linear range were 0.12 pg mL–1 (S/N = 3) and 0.0005–10.00 ng mL–1, respectively. The satisfying results provide a promising approach for clinical detection of PSA in human serum.

A novel, green, one-pot synthesis of gold nanoparticles (AuNPs) was obtained by the redox reaction between AuCl4– and hydroxylatopillar[5]arene (HP5) in aqueous solution with the aid of OH– at room temperature without the need of a traditional harsh reducing agent such as NaBH4, N2H4, etc. Monodisperse AuNPs with a uniform diameter of ∼5.0 nm are fabricated via the proposed one-step colloidal synthesis route by using HP5 as both reducing agent and stabilizer, while AuNPs cannot be effectively protected by noncyclic monomers of HP5. The FTIR, 13C NMR, and XPS studies demonstrated that the hydroxy groups in HP5 reduce Au3+ into Au0, which leads to nucleation, growth, and formation of AuNPs, and the hydroxy groups themselves are oxidized to carboxyl groups. It is surprising that the HP5 functionalized AuNPs can self-assemble and form multiple well-defined architectures, including vesicles, like nanotubes, and one-/two-dimensional (1D/2D) nanostructures without the need of a guest mediator. The self-assembly ...

The increasingly serious environmental problems make it urgent to develop a new type of sustainable green material which can degrade pollutants and monitor human health. However, the traditional preparation methods are frequently limited by tedious operations, high-energy consumption, and massive pollution. Herein, we present a facile and green method for preparation of MnO2 nanoflakes mediated by macrocyclic molecule calix[8]arene. The MnO2 nanoflakes in situ grew on the preformed gold nanoparticles, forming an impressive core–shell Au@MnO2 flake-like nanocomposite. The catalytic properties of Au@MnO2 composite for reduction of 4-NP and degradation of MB were 2.4 and 187 times better than commercial Pd/C, respectively. Meanwhile, the as-synthesized Au@MnO2 nanocomposite exhibited specially excellent sensitivity and selectivity for detection of GSH with a limit of detection (LOD) of 0.11 μM. The core–shell nanostructured Au@MnO2 shows great potential value for the sustainable development of the environmen...

A sensitive and selective fluorescence approach based on a competitive host–guest interaction between amphiphilic pillar[5]arene (amPA5) and signal probe (acridine orange, AO)/target molecule (acetaminophen, AP) was developed by using amPA5 functionalized reduced graphene oxide (amPA5-RGO) as a receptor. Due to the host–guest interaction, AO and AP molecules both can enter into the hydrophobic inner cavity of amPA5 that could form a complex of 1:1 guest–host with amPA5 according to the size of molecules and the cavity of amPA5, but the AP interacts more strongly with amPA5 than with AO, so it can detect AP by the host-guest competition. The low detection limit of 0.05 μM (S/N=3) and a linear response range of 0.1–4.0 μM and 4.0–32 μM for AP was obtained by using this method. It had lower detection limit and wider linear range than other methods, therefore, it was successfully utilized to detect AP in serum samples, and exhibited a promising application in practice. The molecular docking studies indicated that the major driving forces for the formation of the inclusion complex of AP and amPA5 are hydrogen bonding, π-π interactions, and hydrophobic interactions.

In this work, the molecular recognition of dimethomorph by disulfide bridged β–cyclodextrin (SS–β–CD) was studied by UV spectroscopy, 2 D NMR, and molecular modeling. The results indicated that the SS–β–CD/dimethomorph was more stable than β–CD/dimethomorph, which is ascribed to the fact that the disulfide chain plays an important role in stabilizing the appropriate dual-CD conformation and also promoting the inclusion of the host and guest. In addition, a robust fluorescence method for dimethomorph sensing has been developed based on competitive host–guest interaction by selecting safranine T (ST) as optical indicator and SS–β–CD functionalized reduced graphene oxide (SS–β–CD–RGO) as the receptor. Upon the presence of dimethomorph to the pre-formed SS–β–CD–RGO·ST complex, the ST molecule is displaced by dimethomorph, leading to a “switch–on” fluorescence response. That is due to the fact that the binding constant of the dimethomorph/SS–β–CD complex was more than 5 times greater than that of ST/SS–β–CD. The fluorescence intensity of SS–β–CD–RGO·ST complex increased linearly with increasing concentration of dimethomorph ranging from 0.50 to 20.0 μM. The proposed method showed a detection limit of 0.11 μM for dimethomorph, and was successfully applied for the determination of dimethomorph residues in vegetables (cabbage, spinach) and environmental samples (water, soil) with good precision and recoveries from 96.5% to 104%.

Graphdiyne (GD), a novel two dimensional (2D) carbon material, has earned a lot of attention in recent years. Constructing a novel hybrid nanomaterial based on GD, macrocyclic host and Au nanoparticles is an effective strategy for heterogeneous catalysis applications. While tremendous advancements in the preparation of two dimensional (2D) materials anchoring Au nanoparticles have been made, it is an urgent requirement to explore a green, efficient and facile approach for obtaining small-sized Au nanoparticles. The use of the 2D material graphdiyne (GD) presents more-promising candidates for constructing excellent sites for loading metal nanoparticles. In this study, a novel 2D heterogeneous hybrid nanomaterial (P5A-Au-GD) based on GD and pillar[5]arene (P5A)-reduced Au nanoparticles (P5A-Au) was successfully prepared. In this strategy, the P5A can reduce HAuCl4 with the aid of NaOH in the dispersion of GD. Accordingly, the generated P5A-Au can immediately interact with GD to form the P5A-Au-GD hybrid nanomaterial without any harsh reduced materials or other energies. The Au nanoparticles with average diameter of 2–3 nm are homogeneously dispersed on the surface of GD. The heterogeneous 2D catalyst of P5A-Au-GD shows high catalytic performances in the reduction of 4-nitrophenol and methylene blue by comparing commercial Pd/C catalyst. Meanwhile, the unique 2D heterogeneous hybrid material P5A-Au-GD exhibits durable recyclability and stability during the catalytic reaction. Considering the outstanding merits of the heterogeneous 2D catalyst of P5A-Au-GD as well as the simple and green preparation, this study might not only present enormous opportunities for the stabilized, high-performance and sustainable catalysts but also be applied in other frontier studies of sustainable functionalized nanocomposites and advanced materials.

An ultrasensitive and highly selective electrochemical method is described for the determination of dopamine (DA). It is based on the use of a multi-functional nanomaterial composed of water-soluble pillar[5]arene (WP5), dihydroxylatopillar[5]arene (2HP5)-modified gold nanoparticles (GNPs), and graphitic carbon nitride (g-C3N4), with an architecture of type 2HP5@GNP@WP5@g-C3N4. The modified GNPs were prepared in the presence of 2HP5 that acts as reducing agent and stabilizer in the formation of GNPs. 2HP5@GNP acts as an electrocatalyst in sensing DA. The WP5@g-C3N4 nanocomposite is obtained by π interaction between WP5 and g-C3N4 after sonication in the presence of WP5. The composite serves as a host for recognition and gathering DA on the surface of the electrode. The host-guest recognition mechanism between WP5 and DA is studied by 1H NMR and UV-vis. The electrode, best operated at a working potential of 0.18 V (vs. SCE), works in the concentration range of 0.012–5.0 μM DA and has a 4 nM detection limit.

We develop a novel and fast colorimetric sensing platform for spermine (Sp) by using macrocyclic host hydroxyl pillar[5]arene (P5) molecule reduced and stabilized Au nanoparticles via the supramolecular host-guest recognition interaction between P5 and Sp. The P5-modified Au nanoparticles (P5-Au) are easily obtained by redox reaction between hydroxyl groups in P5 and Au3+ in HAuCl4, where hydroxyl groups are oxidized to carboxyl groups and Au3+ is reduced to Au0+ under alkali catalysis at room temperature without NaBH4 or other reducing agent. A uniform diameter of about 5.0 nm and wine red color P5-Au nanoparticles can be synthesized by this green and rapid method. The mechanism of redox reaction between P5 and HAuCl4 is studied by the XPS and 13C NMR, and the P5-Au is characterized by the TEM, XRD and XPS.

Nitrogen-doped carbon dots (N-CDs) with a quantum yield of 41 ± 3% and excellent stability were prepared and are shown to be viable probes for the determination of ferric ions, which is a strong quencher of fluorescence. The absorption peak of the N-CDs is located at 325 nm. The optimal excitation and emission wavelengths of the N-CDs are 340 nm and 430 nm, respectively. The fluorometric response to Fe(III) is linear in the ranges between 1.0 and 21.0 μM and between 0.05 and 30.0 μM, and the limits of detection are 0.28 μM in case of colorimetry and 13.5 nM in case of fluorometry. Quenching by Fe(III) is mainly attributed to a combination of chelation (static quenching) and inner filter effect. The N-CDs also can be used as a new sort of fluorescent ink owing to the strong luminous performance and chemical inertness. Graphic abstract The illustration for synthesis of the N-CDs and its applications for colorimetric and fluorescent detection of Fe

A turn-on fluorescent sensing platform for labetalol determination has been developed based on competitive host–guest interaction between p-sulfonated calix[6]arene (SCX6) and signal probe/target molecules by using SCX6 functionalized MnO2@reduced graphene oxide (SCX6-MnO2@RGO) as a receptor. Rhodamine 6G (R6G) and labetalol were selected as the probe and target molecules, respectively. When R6G enters into the SCX6 host, its fluorescence is quenched by MnO2@RGO. However, on addition of labetalol to the preformed R6G·SCX6-MnO2@RGO complex, the R6G molecule is displaced by labetalol from the host of SCX6, leading to a “switch-on” fluorescence response. This is due to the fact that the binding constant of the labetalol/SCX6 complex is much higher than that of R6G/SCX6. The fluorescence intensity of the SCX6-MnO2@RGO·R6G complex increased linearly with increasing concentration of labetalol ranging from 1.0 to 18.0 μM. The proposed method showed a detection limit of 0.25 μM for labetalol. In addition, 2D NMR and molecular modeling studies indicated that the salicylamide part of the labetalol molecule inserted into the cavity of SCX6, while the phenylpropyl group located outside of the SCX6 host.

Ultrasensitive, high selective and rapid monitoring of explosives has increasingly become a crucial and urgent challenge in order to protect environment and prevent terrorist threats, which should be addressed timely. In this study, a highly selective and sensitive electrochemical sensing platform based on two dimensional (2D) heterogeneous functionalized material for determination dangerous and explosive sodium picrate (SP) and analogue picric acid (PA) is successfully established. To begin with, the dihydroxylatopillar [6]arene (2HP6) modified Au nanoparticles (2HP6@Au) can be easily obtained by 2HP6 reduced and stabilized Au nanoparticles at room temperature. Then, assembly of 2HP6@Au on the surface of cationic pillar [6]arene (CP6) functionalized covalent organic framework (COF) can obtain 2D heterogeneous composite (2HP6@Au@CP6@COF) for rapid and sensitive detection of SP. The electrode, best operated at a working potential of −0.4 to −1.1 V (vs. Hg/Hg2Cl2), works in the concentration range of 0.005–120 μM SP and has a 0.0017 μM detection limit. The Au nanoparticles play an electrocatalytic role in sensing SP, the 2HP6 and CP6 serve as a prominent material for gathering and recognition SP onto the surface of electrode, respectively. The SP can thread into the cavity of pillar [6]arene and form a 1:1 [2]pseudorotaxanetype complex. The SP can be highly captured by CP6 via the excellent supramolecular host-guest interactions (including π interaction, hydrophobic interactions and electrostatic interactions). Consequently, this work might present a green strategy for preparation 2D heterogeneous functionalized hybrid material in catalysis, sensing and other fields.

While tremendous advancements in 2D materials anchoring Au nanoparticles have been made, it is an urgent challenge to explore a green and facile approach for obtaining small-size Au nanoparticles. The rise of 2D covalent organic framework (COF) presents more-promising candidates for constructing excellent sites for loading metal nanoparticles. In this study, a novel 2D heterogeneous hybrid nanomaterial (P6-Au-COF) based on COF and pillar[6]arene (P6) reduced Au nanoparticles (P6-Au) is prepared by a simple and green procedure. The Au nanoparticles with an average small diameter of 2-3 nm are homogeneously dispersed on the surface of the COF. The P6-Au-COF hybrid material shows highly catalytic performance for the reduction of nitrophenol isomers when compared with commercial Pd/C catalyst and other reported materials. The P6-Au-COF hybrid material exhibits durable recyclablility and stability during the catalytic reaction. Considering the outstanding merits of the heterogeneous 2D catalyst of P6-Au-COF as well as the simple and green preparation, this research might not only present enormous opportunities for stabilized, high-performance and sustainable catalysts, but be applied in other frontier study of sustainable functionalized nanocomposites and advanced materials.