A rotary disc-structured triboelectric nanogenerator (rd-TENG) on the basis of free-standing electrification has been designed, where the aluminum composite panel has not been tailored to the stator becauseit is commercially available and cost-effective, has good electronic conductivity, and is easily processed. With the rotating speed increasing from 200 to 1000 rpm, the short-circuit current (Isc) is sharply enhanced from 50 μA to 200 μA, while the measured open-circuit voltage (Voc) and transferred charge (Qtr) almost keep constant, 600 V and 0.4 μC, respectively. The matched load for the rd-TENG at a rotating speed of 600 rpm is 2.7 MΩ, generating a maximum power of 19.75 mW, which corresponds to a maximum power density of 2.28 W m–2. Using the electric power generated by such a rd-TENG, highly toxic and carcinogenic 4-aminoazobenzene can be selectively treated to produce CO2 or an oligomer via reasonably controlling electrochemical oxidation potentials. The underlying mechanism is tentatively proposed based on the cyclic voltammogram, gas chromatograph-mass spectrometer, electrochemical impedance spectroscopy, and UV–vis spectra. Here the electrochemical degradation in a single-compartment cell is more valid, preferable, and feasible. The output Voc and rectified current of rd-TENG guarantee its extensive application to self-power electrochemical degradation of other azo compounds, i.e., 2-(4-dimethylaminophenylazo) benzoic acid, to CO2. This work suggests that rd-TENG, sustainable energy, can be feasibly designed to self-power a practical electrochemical treatment of dyeing wastewater by harvesting vibration energy.Keywords: 4-aminoazobenzene; free-standing; rotary disc structure; self-power; triboelectric nanogenerator;

•A new kind of N-doped-carbon-coated Fe3O4 (denoted as NC@Fe3O4) ORR electrocatalyst is successfully prepared.•The NC@Fe3O4-900-1.5 shows remarkable electrocatalytic ORR performance.•The in-situ carbon coating can block the aggregation of the iron-based particles.•This boosts the non-noble-metal hybrid ORR electrocatalysts derived from MOFs.Nowadays, the hybrids of non-noble metal and heteroatom-doped carbon, especially, transition-metal-nitrogen-carbon materials, have been extensively studied as promising next-generation oxygen reduction reaction (ORR) catalysts in energy conversion. However, the pyrolysis of normal metal/nitrogen/carbon-containing precursors usually generates uncontrollable agglomeration or inhomogeneous microstructure, hence leading to insufficient exposure of the active sites and poor mass transport. In this work, a new strategy for fabricating N-doped-carbon-coated Fe3O4 (denoted as NC@Fe3O4) is proposed by the pyrolysis of polyaniline (PANI)-coated Fe-based metal organic frameworks (MIL-101-Fe). The optimal catalyst exhibits a very positive ORR onset potential close to that of Pt/C, quasi-four-electron-transfer pathway and high long-term cycle stability in alkaline media. This work demonstrates the crucial role of thin PANI film (a highly conductive skeleton and heteroatoms sources) together with MOFs to rationalize the superior ORR performance for the resulting NC@Fe3O4. The generality of the conductive-polymer-layer-assisted synthetic strategy is expected to further boost the electrocatalytic activity of universal non-noble-metal hybrid electrocatalyst for practical fuel-cell applications.Download high-res image (278KB)Download full-size image

•A self-powered electro-Fenton degradation system is demonstrated for the first time.•A novel flexible multilayer TENG with the sponge as the buffer layer is designed.•This work provides a guidance for more rational design of biomass-derived carbon electrocatalysts in electro-Fenton system.Based on the advantages of electro-Fenton (EF) and our works on the flexible design of triboelectric nanogenerator (TENG) and biomass carbon materials, a self-powered EF system is demonstrated. It is driven by a robust and flexible multilayered TENG (RFM-TENG) using carbon materials derived from magnolia flowers as the cathode for oxygen reduction. The synthetic mesoporous carbon materials have a large surface area (1226 m2 g−1), favoring dissolved oxygen mass transfer and promoting the oxygen reduction process. With the sponge as the buffer layer and pre-charge injection, the short-circuit current, transferred charge and open-circuit voltage of RFM-TENG are 960 μA, 2.8 μC and 1050 V, respectively, and the maximum power density reaches 5.5 W m−2 at a load resistance of 1 MΩ. Driven by this RFM-TENG, the persistent organic pollutant, basic orange 2, can be degraded to CO2 by hydroxyl radical (•OH) generated during EF process. Such mechanism is proposed based on the cyclic voltammogram, gas chromatograph-mass spectrometer, UV−vis spectra and the H2O2 measurement. With compelling features of the efficient EF method, versatile TENG and biomass-derived carbon materials, this work pioneers the alliance of TENG, carbon-based electrodes and EF to self-power the organic pollutants degradation for sustainable environmental protection.Based on the advantages of EF process and our works on the flexible design of TENGs and carbon materials, we synthesize the carbon materials from magnolia flowers as the cathode for oxygen reduction and design a robust and flexible multilayer triboelectric nanogenerator (RFM-TENG) with the sponge as the buffer layer for the first time to realize the self-powered degradation of basic orange 2 (BO2) via electro-Fenton system. This work pioneers the combination of the TENG with biomass-based carbon materials to self-power electro-Fenton degradation of organic pollutants for environmental protection.Download high-res image (218KB)Download full-size image

The hierarchically porous nitrogen-doped polyaniline-boric acid-polyvinyl alcohol (PBP) carbon aerogels (PBP/CAs) are synthesized through chemical crosslinking engineered and KOH activation processes. The optimal sample with a high BET surface area of 2675 m2 g−1, a wide micropore and mesopores size distribution (0.5–4 nm), in-situ nitrogen-doping (0.50%) and surface hydrophilicity (contact angle is 12.9°), exhibits a high specific capacitance of 497 F g−1 in 1 mol L−1 H2SO4 and 400 F g−1 in 6 mol L−1 KOH at a current density of 1 A g−1, and delivers excellent cycling stability with the capacitance retention of 92.80% and 90.71% after 10000 cycles at 30 A g−1, respectively. And it also reveals a high energy density of 12.60 Wh Kg−1 and 11.05 Wh Kg−1 in acid and alkaline electrolytes, respectively. More significantly, the assembled capacitors can be directly applied to degrade azo dye of 4-aminoazobenzene. Our work not only highlights the advantages of one-pot chemical crosslinking route to prepare nitrogen-doped PBP/CAs under ambient condition (e.g. room temperature, cost-effective raw materials, time-saving and routine equipment et al.), but also offers competitive electrodes for high-performance pH-universal electrochemical double-layer capacitor with a potential broad application in energy conversion devices.Download high-res image (216KB)Download full-size image

Besides a lack of low-cost electrode materials, the match between the electrode materials and electrolytes is one of the top issues to achieve high-rate electrochemical supercapacitors. Herein, we report an environmentally friendly strategy to prepare three-dimensionally interconnected carbon nanorings (TDICNs) from biomass waste, batata leaves and stalks (BLS). The microstructure of TDICNs matches well with acidic and alkaline electrolytes, making them exhibit high specific capacitances of 532.5 F g−1 (1 A g−1) and 264.0 F g−1 (30 A g−1), excellent capacitance retention (95.1% and 91.7% after 1000 cycles at 1 A g−1 and 10 000 cycles at 30 A g−1, respectively) and a high energy density of 25.8–11.9 W h kg−1 with a power density of 249.5–13 068.0 W kg−1 in 1 mol L−1 H2SO4 aqueous electrolyte. In 6 mol L−1 KOH electrolyte, they still exhibit high specific capacitances of 350.0 F g−1 (1 A g−1) and 246.9 F g−1 (30 A g−1), excellent cycling stability (95.06% and 91.1% of capacitance retention after 1000 (1 A g−1) and 10 000 (30 A g−1) cycles, respectively), a high energy density of 24.5 W h kg−1 and a power density of 12 918.0 W kg−1.

A series of nitrogen and oxygen enriched porous carbons are prepared from poly-N-phenylethanolamine (PNPEA) and polyaniline (PANI) conducting polymers through pyrolysis, chemical activation, and oxidation processes. Ar or N2-adsorption, Fourier transform infrared, and X-ray photoelectron spectroscopy are used to characterize the surface areas, pore volumes, surface chemical compositions, and oxygen and nitrogen content. Mikhail and Brunauer micropore analytical method (MP method) is successfully used to analyze the micropore size distribution of the samples. The electrochemical behavior of the samples is studied in two- and three-electrode cells. The contribution of pseudocapacitance is confirmed by cyclic voltammetry and galvanostatic tests performed in acidic (H2SO4) and basic (KOH) media. The potential drop and the equivalent series resistance value certify that the samples with wide micropore size distribution possess low interface resistances. A sample with a Brunauer–Emmett–Teller (BET) surface area of 760 m2 g–1, nitrogen content of 3.02 at. %, oxygen content of 16.65 at. %, and a wide micropore size distribution presents the best performance, reaching a value of 370 F g–1 at 0.5 A g–1 and 248 F g–1 at 30 A g–1, and maintaining capacitance retention ration of 96% at 1 A g–1 (over 1000 cycles) and 92% at 30 A g–1 (over 10 000 cycles), respectively. The results obtained for all the samples agree with correlation among capacitance, functional group, and porosity, which indicates that an appropriate selection of the surface chemistry, a reasonable pore size distribution, and a moderate BET surface area may be promising to achieve high-rate-performance supercapacitors.

•Self-template strategy is reported to synthesize interconnected porous nitrogen-doped CA.•The synergistic effect endows the obtained CA with high specific capacitance considerable cycle performance.•The symmetric supercapacitor delivers an energy density of 22.75 Wh kg−1 at power density of 262.5 W kg−1.•The sample has a potential application in supplying a peak power for electrochromic device.Three-dimensional (3D) interconnected porous nitrogen-doped carbon aerogels (CAs) have been successfully prepared with polyvinyl alcohol and nitrogen-containing N-phenylethanolamine as carbon and in-situ nitrogen sources, and boric acid as both crosslinking agent and 3D self-template. After drying, carbonization and KOH-activation treatment, the as-obtained CAs exhibit large specific surface area, hierarchically porous structure, heteroatom doping and superhydrophilicity. The optimal sample shows a high surface area up to 2016 m2 g−1 with a total pore volume of 1.179 cm3 g−1. The synergistic effect of the reasonably hierarchical porosity, high effective surface area utilization, superhydrophilicity, and heteroatom pseudocapacitance are in favor of high specific capacitance of 467 F g−1 in three-electrode system and considerable cycle performance of 85.7%, 90.9% retention over 10,000 cycles at 20 A g−1 and 30 A g−1. Moreover, the symmetric supercapacitor configuration delivers an energy density of 22.75 Wh kg−1 at power density of 262.5 W kg−1 and 7.6 Wh kg−1 at power density of 9572 W kg−1. Here, we pioneer an in-situ self-template approach for fabricating hierarchically porous aerogels with a potential application in supplying a peak power for hybrid electric vehicles, memory backup systems, cold-starting assistants and especially electrochromic devices as demonstrated in our case.

We present a cost-effective approach to dispose of amaranthus waste (the discarded leaves and stalks of amaranthus and the extract remains of natural amaranthus red) to yield nitrogen-doped carbon. Amaranthus waste is a natural, abundantly available, and yearly renewable source, acting as a single precursor for nitrogen (mainly from the lysine-rich amino acids) as well as carbon. It therefore eliminates the need for multiple hazardous chemicals including organic precursors for similar synthesis processes. Our facile experimental strategy without any activation supports reasonable nitrogen doping in porous carbon along with a high surface area and excellent conductivity, which leads to a superior electrocatalytic oxygen reduction activity and proves to be a promising alternative for costly Pt-based electrocatalysts in fuel cells in terms of excellent electrocatalytic performance, high selectivity, and long durability. This judicious transformation of organic-rich waste not only addresses the disposal issue, but also generates valuable functional carbon materials from the discard. Our as-synthesized carbon will certainly be believed to be a trend setter and have greater economic ramifications by creating value-added materials from waste.

Substituting sustainable/cost-effective catalysts for scarce and costly metal ones is currently among the major targets of sustainable chemistry. Herein, we report the synthesis of N-, S-, and P-tridoped worst-weed-derived carbon nanorings (WWCNRs) that can serve as a metal-free and selective electrocatalyst for the oxygen reduction reaction (ORR). The WWCNRs are synthesized via activation-free polymerization of worst weed, Eclipta prostrata, and then removal of the metallic residues by using HCl. The WWCNRs exhibit good catalytic activity towards the 4 electron-transfer ORR with a low onset potential and high kinetic limiting current density, along with high selectivity (introducing CO, the sample loses only <7% of its original activity, in contrast to more than 30% loss of the original activity for 20 wt% Pt/C over 4000 s of the continuous ORR) and long durability (94% of the initial current still persists at the sample electrode compared with a 87% current retention at commercial Pt/C electrodes after 18000 s). The present work highlights the smart transformation of organic-rich worst weed into value-added functional materials with great potential for applications such as fuel cells, lithium–air batteries, photocatalysis, and heterocatalysis.

An efficient soft-template method is proposed for the synthesis of peanut shell-like porous carbon as high-performance supercapacitor electrode materials. The procedure is based on the pyrolysis and chemical activation processes using N-phenylethanolamine as precursor and KOH as activation agent. In a three-electrode system, the resultant carbon material has a specific capacitance of 356 F g–1 at 1 A g–1 and a good stability over 1000 cycles. Besides, at a high current density of 30 A g–1, it has a specific capacitance of 249 F g–1 and maintains 96% after 10 000 cycles. In two-electrode cell configuration, it delivers about 21.53 Wh kg–1 at a current density of 20 A g–1, which is about 7 times higher than the commercial device (<3 Wh kg–1). Both high specific capacitance and excellent cycling stabilities guarantee its utilization in supercapacitors.Keywords: conducting polymer; energy density; nitrogen-doping; power density; supercapacitor

Self-assembled cuprous oxide nanoparticles supported on reduced graphene oxide are synthesized by a chemical reduction method in aqueous systems. The results of field emission scanning electron microscopy and transmission electron microscopy demonstrate that the obtained sample features a hollow ball structure through the self-assembly. Moreover, the cuprous oxide particles dissociate into tiny lamellar structures with a diameter of 3 nm in an aqueous medium. The catalytic activity of the sample was investigated using the reduction of nitrophenols to aminophenols with excess sodium borohydride as the model reaction. The kinetics of reduction was proved to follow pseudo first order kinetics. The rates of catalytic reduction of nitrophenols have been found to follow the sequence: 2-nitrophenol > 4-nitrophenol > 3-nitrophenol, and the activation energies are 50.17 kJ mol−1, 79.92 kJ mol−1 and 63.86 kJ mol−1 for 2-nitrophenol, 3-nitrophenol and 4-nitrophenol, respectively. In addition, the reusability of the Cu2O/RGO compounds was also studied and the results showed that the compounds could be reused many times with nearly invariable high catalytic efficiency.

•S, N co-doped carbon is synthesized using waste honeysuckle as the single precursor.•The sample exhibits excellent ORR catalytic compared to the commercial Pt/C catalyst.•The excellent ORR performance lies in improved.•The treatment of waste provides value-added carbon for energy and environment.In today׳s materials chemistry, to develop functional carbon nanomaterials from cheap nature provided materials becomes a highly attractive subject, which, to some extent, encompasses the economic, sustainable, environmental, and social issues. In spite of the considerable progress in engineering doped carbon as oxygen reduction reaction (ORR) electrocatalyst from biomass, there is still a long way for the large-scale application in commercializing fuel cells. Here, a three-dimensional (3D) porous sulfur, nitrogen co-doped carbon is synthesized using honeysuckles as the single precursor. The product has a graphene-like structure and exhibits excellent ORR activity in 0.1 M KOH medium with superior tolerance to methanol and stability to those of Johnson Matthey Pt/C catalyst. Such excellent ORR performance may be ascribed to the synergistic effect, including high ORR catalytic sites caused by sulfur, nitrogen heteroatoms doping, favorable reactant transport channels provided by pore structures, and fast electron transfer rate induced by 3D continuous networks. Our idea on developing such dual-heteroatoms doped carbon materials with abundant active sites as well as four electron transfer and superior reactant transport channels would be a good solution to fuel cell cathode electrocatalyst.

•A nitrogen-doped fullerene-like carbon shell catalyst is readily synthesized using fallen ginkgo leaves as the starting materials.•The pyrolyzing temperature here is as low as 800 °C to cause nongraphitizing carbon to evolve into closed nanocages of fullerene-like structures, which coincides with the consensus that the presence of N promotes the formation of fullerene-like arrangements at lower temperatures.•The product exhibits excellent electrocatalytic activity toward four-electron ORR with long-term stability for fuel cell. This is well consistent with the quantum mechanics calculations.•This is the first report on the green and cost-effective synthesis of N-doped fullerene-like carbon and its applications as metal-free ORR catalyst.Implementation of non-precious electrocatalysts towards oxygen reduction reaction (ORR) falls in the central focus on fulfilling cost-affordable and high-performance fuel cells and metal/air batteries. Recent first-principles spin-polarized DFT calculations simulated the electrocatalytic ORR reaction process on N-doped C60 fullerene (N-C60) and found that O2 can be chemisorbed and reduced on N-C60, indicating that N-C60 is a potential cathode catalyst for hydrogen fuel cells. In this work, a novel waste-to-resource strategy to convert fallen ginkgo leaves into this new kind of ORR electrocatalyst, nitrogen-doped fullerene-like carbon shell (NDCS), is presented. N is derived from fallen ginkgo leaves, where 10.9–15.5 wt% proteins are present. The obtained NDCS possesses 100% catalysis selectivity towards four-electron pathway, and its ORR activities outperform most of the other existing carbon-based catalysts. It also shows significantly improved tolerance against methanol and enhanced long-term stability, compared with the commercial platinum-loaded carbon catalyst. Thus it is experimentally demonstrated that the NDCS is a promising future ORR catalyst, which is well consistent with the quantum mechanics calculations. Additionally, the NDCS presents a high reversible capacity (750 mA h g−1 at 0.02 A/g) in Li-ion batteries. Since fallen ginkgo leaves are readily available, our study represents an exciting direction for sustainable and low-cost energy conversion and storage materials.Under N2 atmosphere at 800 °C, fallen gingko leaves is deliberately transformed into nitrogen-doped fullerene-like carbon shell, which can catalyze a four-electron transfer process for oxygen reduction reaction with a much higher electrocatalytic activity, lower overpotential, smaller crossover effect, and better long-term operation stability than that of commercially available or similar platinum-based electrodes in alkaline electrolyte.

The urgent need for sustainable energy development depends on the progress of green technologies, which have steered hot research areas into environmentally benign approaches via inexpensive precursors and abundant resources obtained directly from nature for energy devices such as fuel cells and supercapacitors. By using fermented rice as starting materials, we herein demonstrate a facile, green and scalable approach to synthesize porous N-doped carbon spheres characterised by high specific surface areas (2105.9 m2 g−1) and high porosity (1.14 cm3 g−1), which exhibit not only excellent electrocatalytic activity toward the four-electron oxygen reduction reaction with long-term stability for fuel cells, but also have excellent resistance to crossover effects and CO poisoning superior to that of the commercial Pt/C catalyst. Furthermore, the naturally derived porous N-doped carbon spheres, used as the active electrode materials, present superior performance for capacitors with a capacitance of 219 F g−1 at a high discharge current density of 15 A g−1 and good cycling stability for over 4400 cycles. This work shows a good example for taking advantage of the abundant resources provided by nature, and opening the door for the creation of functional materials with promising applications in high-performance renewable devices related to energy conversion and storage.

Fuel cells are promising candidates for clean and high-efficient energy conversion in the future. The development of carbon-based inexpensive metal-free ORR catalysts has become one of the most attractive topics in the fuel cell field. Herein, we report a N-doped carbon catalyst with a surface area of up to 1895.5 m2 g−1 using a natural product (bamboo fungus) as the starting material. In 0.1 M KOH electrolyte, the ORR onset potential for the catalyst is high up to 0.089 V vs. Ag/AgCl. Moreover, it shows superior stability, fuel crossover resistance, and selective activity to a commercial Pt/C catalyst. In addition, the sample displays excellent stability, i.e. no obvious decrease in current was observed after 1000 continuous cycles between −0.7 and 0.3 V in O2-saturated 0.1 M KOH. Moreover, both the structural characterizations and electrochemical tests verify that the treatment techniques of biomass have an important impact on the materials.

A green strategy has been developed for synthesizing nitrogen-doped carbon dots (N-CDs) via hydrothermal treatment of willow leaves. The supernatant exhibits strong blue fluorescence under UV radiation and can be directly used as a fluorescent ink, while the solid product with pyrolysis possesses excellent electrocatalytic activity for a highly efficient oxygen reduction reaction with great stability and methanol/CO tolerance superior to a commercial Pt/C catalyst.

•The Mn–Na oxide with high valence can be easily formed and result in impurity diffraction peaks for the LiMn2O4.•Feeding N2 and adding hydrazine could effectively prevent Mn2+ from being oxidized into the Mn–Na oxide.•LiMn2O4 synthesized by our method delivers the excellent structural characteristics and electrochemical performances.As a precursor of spinel LiMn2O4 cathode, manganese oxide is prepared by co-precipitation via a two-step drying method. The effects of precursor treatment on the structure, morphology, and electrochemical performance of the synthesized spinel LiMn2O4 are studied using contrasting experiments involving the addition of hydrazine, N2, and H2O2. The tests show that different treatments have a great effect on the crystal structure, morphology, tap density, and electrochemical performance of LiMn2O4. When the precursor is treated by adding hydrazine and pure N2, the synthesized LiMn2O4 shows an integral lattice, uniform particle size, a pure spinel phase with an ordered octahedral crystal structure, and high tap density (2.23 g cm−3). The electrochemical results show that spinel LiMn2O4 exhibits higher specific capacity and better cyclic stability than other samples, especially at an elevated temperature and high discharge current. The initial discharge capacity of the electrode is 110.8 mAh g−1 at a rate of 3 °C, and exhibits a good capacity retention of 96.4% after 30 cycles; at a rate of 5 °C, the initial discharge capacity is 107.5 mAh g−1, with a capacity retention of 87.3% after 50 cycles.

•Nitrogen-doped carbon materials via hydrothermal treatment of Gastrodia elata.•Excellent electrocatalytic activity for oxygen reduction reaction and superior crossover resistance, CO tolerance, and catalytic stability to a commercial Pt/C catalyst.•The supernatant exhibits strong blue fluorescence under UV radiation, showing its promising potential as new-generation decorative materials.•One-stone-two-birds strategy for energy and environmental problems.We demonstrate a one-stone-two-birds strategy for synthesizing nitrogen-doped carbon materials via hydrothermal treatment of Gastrodia elata. The solid product followed by further ionothermal pyrolysis exhibits excellent electrocatalytic activity for oxygen reduction reaction via a dominant four-electron oxygen reduction pathway in alkaline medium, and shows superior crossover resistance, CO tolerance, and catalytic stability to a commercial Pt/C catalyst. The supernatant exhibits strong blue fluorescence under UV radiation, showing its promising potential as new-generation decorative materials combining with Chinese folk paper-cut art and displaying mysterious and stimulating stage effects. Given these excellent electrocatalytic and optical properties, ease of preparation, and abundant resources, such one-stone-two-birds methodology not only endows the products with desirable functionality, but also timely reminds our researchers of the well-accepted saying that things should be used to their best advantages, which becomes more and more urgent especially in recent days characteristic of progressive resource scarcity.A one-stone-two-birds strategy for synthesizing nitrogen-doped carbon materials with excellent electrocatalytic activity for oxygen reduction reaction and as new-generation decorative materials.

This paper reports a simple one-step growth of hierarchically micro/nanostructured porous metallic copper microspheres with high yield at room temperature. The key growth strategy is to use phenol and ascorbic acid as porogen and reducing agents, respectively, to induce the growth of the porous hierarchical micro/nanostructure. The samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption. It is found that the morphology and structure of the porous Cu microspheres are highly dependent on the phenol added. Compared to the commercial Cu powders and Cu sheets with dense internal structure, hierarchically micro/nanostructured porous metallic copper microspheres show excellent superhydrophilic surface property and much higher catalytic activity for the reduction of 4-nitrophenol, demonstrating the significance of the pore structure of the copper materials. Their potential applications in catalysis for oxygen reduction reaction of fuel cells are also explored. All these features make the as-prepared porous copper microspheres a highly attractive candidate for multi-functional materials.

Hierarchical micro/nano arrays can offer both the advantages of nano-sized building blocks and micro- or submicrometer-sized ordered arrays, therefore representing one kind of potential functional materials and having received enormous attention for a wealth of applications. In this study, four-dimensionally flower-like CuO micro/nanostructures decorated by Au nanoparticles are synthesized via an environmentally friendly route assisted by polyethylene glycol. Experiments reveal that the product demonstrates high catalytic performance for the reduction of 4-nitrophenol using NaBH4 as the reducing agent, which could be attributed to the rich Au/CuO interfaces in the samples. Compared to the pure noble metal catalysts, the obtained sample is quite economic. In terms of methodology and cost-effectiveness, this study proposes an economically useful and green method to produce a highly efficient metal-based catalyst. It is also a good example for the organic combination of green chemistry and functional materials.

Three-dimensionally (3D) hierarchical micro/nano oriented arrays constructed from nanometer-sized building blocks represent an important group of materials and have received enormous attention for a series of applications because they can offer both the advantages of nanosized building blocks and micro- or submicrometer-sized ordered arrays. In this work, 3D flower-like superhydrophilic CuO micro/nanostructures decorated by Ag nanoparticles were synthesized via an amino acid-assisted biomimetic hydrothermal method. Experiments reveal that the product demonstrates excellent sunlight self-cleaning performance in terms of wettability (without the help of high-free-energy compounds and in the absence of UV irradiation) and enhanced photocatalytic activities, which portends a bright future for this material as self-cleaning photovoltaic coatings. It is also a good example for the organic combination of green chemistry and functional materials.

Ag/ZnO metal–semiconductor nanocomposites with hierarchical micro/nanostructure have been prepared by the hydrothermal synthesis in the presence of bovine serum albumin (BSA). The results suggest that this biomolecule-assisted hydrothermal method is an efficient route for the fabrication of Ag/ZnO nanocomposites by using BSA both a shape controller and a reducing agent of Ag+ ions. Moreover, Ag nanoparticles on the ZnO act as electron sinks, improving the separation of photogenerated electrons and holes, increasing the surface hydroxyl contents of ZnO, facilitating trapping the photoinduced electrons and holes to form more active hydroxyl radicals, and thus, enhancing the photocatalytic efficiency of ZnO. This is a good example for the organic combination of green chemistry and functional materials.Graphical AbstractA green strategy is report to construct Ag/ZnO metal–semiconductor nanocomposites with hierarchical micro/nanostructure and enhanced photocatalytic activity.Research highlights► Hierarchical micro/nanostructured Ag/ZnO nanocomposites have been prepared via a green route. ► Ag nanoparticles improve the separation of photogenerated electrons and holes. ► This facilitates trapping the photoinduced electrons and holes to form more hydroxyl radicals. Therefore, it enhances the photocatalytic efficiency of ZnO.

Nanostructured noble metals exhibit an intense optical near field due to surface plasmon resonance, therefore promising widespread applications and being of interest to a broad spectrum of scientists, ranging from physicists, chemists, and materials scientists to biologists. A wealth of research is available discussing the synthesis, characterization, and application of noble metal nanoparticles in optical sensing. However, with respect to the sensitivity of the frequency and width of these surface plasmon resonance modes to the particle’s shape, size, and environment, in nearly every case, success strongly depends on the availability of highly stable, adhesive, and sensitive nanoparticles. This undoubtedly presents a challenging task to nanofabrication. The past decade has witnessed fascinating advances in this field, in particular, the construction of oxide-based hybrid plasmonic interfaces to overcome the problem addressed above by (1) coating the metallic nanostructures with thin overlayers to form sandwiched structures or (2) embedding metallic nanostructures in a dielectric matrix to obtain metal/dielectric matrix nanocomposite films. In this critical review, we focus on recent work related to this field, beginning with a presentation of hybrid films with enhanced structural and optical stability, readily and selectively designed using chemical and physical techniques. We then illustrate their interesting optical properties and demonstrate exciting evidence for the postulated application in surface plasmon sensing fields. Finally, we survey the work remaining to be done for that potential to be realized.

Cauliflower-like CuI nanostructures is realized by an ampicillin-assisted clean, nontoxic, environmentally friendly synthesis strategy at room temperature. The morphology, composition, and phase structure of as-prepared powders were characterized by field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results show that ampicillin plays dual roles, reducing and morphology-directing agents, in the formation of the products. A possible growth mechanism of the cauliflower-like CuI nanostructures is tentatively proposed. The preliminary investigations show that the cauliflower-like CuI structure not only exhibits high catalytic activity with respect to coupling reaction between benzylamine and iodobenzene but also possesses high removal capacity for Cd (II), which may be ascribed to the high specific surface area of the special configuration. To the best of our knowledge, it is the first report that cauliflower-like CuI nanoparticles act as catalyst for coupling reaction and adsorbent for heavy metal ion.Highlights► In this study we report a green, environment-friendly, efficient, and direct one-step process for the preparation of CuI cauliflower. ► The as-formed CuI cauliflower shows excellent catalytic activity for coupling reaction between benzylamine and iodobenzene. ► The cauliflower-like CuI nanostructures have been successfully demonstrated as adsorbent for Cd (II) with high removal capacity. ► To the best of our knowledge, it is the first report that nanostructured CuI acts as catalyst for coupling reaction and adsorbent for heavy metal ion. ► It is also a good example for the organic combination of green chemistry and functional materials.

In the past few years, the study of superhydrophilic surfaces has attracted considerable attention, due to their great potential in not only fundamental research but also practical applications. However, the bottlenecks in this field are (1) the use of UV irradiation, (2) the chemical modification by high-free-energy materials, and (3) the unavailability of useful superhydrophilic surfaces throughout the range of pH values from 0 through 14. In this article, we describe a method for inducing rough features on carbon surfaces using plasma technique to acquire superhydrophilic character. More interestingly and importantly, the as-prepared films are superhydrophilic for not only pure water but also corrosive liquids, such as acidic and basic solutions. This is the first example of superhydrophilicity over the whole range of pH values without the presence of high-free-energy compounds and in the absence of UV irradiation and might open up new perspectives in preparing novel nanoscale interfacial materials. The method of surface design described here does not require the use of masks or lithography, can be applied to very large surfaces in very short time, and herein offers an inexpensive and rapid method for improving the wettability of materials.

•Nitrogen and oxygen dual-doped (NODC-800) and oleophylic carbon aerogel (OCA) were prepared from poplar catkins via different technologies.•NODC-800 delivers excellent ORR electrochemical characteristics.•NODC-800 shows a high capacity for SCs (251 F g−1 at 0.5 A g−1) with nearly 100% retention rate after 1000 cycles.•OCA exhibits high absorption capacity of 81-171 times its own weight and excellent recyclability for different oils and organic solvents.Directly pyrolyzing biowastes has attracted intensive interest, probably because this economical and facile method provides an efficient and versatile platform for synthesizing functional carbons. This study describes the synthesis of different functional carbons from poplar catkins via different processes for multi-purpose applications. Nitrogen and oxygen dual-doped carbon (NODC-800) derived from catkins delivers superior electrochemical characteristics as oxygen reduction reaction (ORR) catalyst in alkaline fuel cell to that of commercial Pt/C in terms of catalytic activity, stability, resistance to methanol cross-over and CO poisoning. In addition, NODC-800 exhibits a high capacity (~251 F g−1 at 0.5 A g−1) with nearly 100% retention rate after 1000 cycles as supercapacitors electrodes. An oleophylic carbon aerogel derived from catkins is proven to be superoleophilic and porous enough to “wet” with oils and organic liquids and repel water completely to achieve oil/water separation. This work is a successful case to take full advantage of raw materials from nature via multiple technologies to achieve energy sustainable development and protect environmental from oils and organic solvents spill.This study describes the synthesis of functional carbons from poplar catkin via multiple channels. Nitrogen and oxygen dual-doped carbon delivers excellent electrochemical characteristics for oxygen reduction reaction and supercapacitors. Oleophylic carbon aerogel is proven to be superoleophilic and highly porous enough to “wet” with oils and organic liquids and repel water completely to achieve oil/water separation.

Substituting sustainable/cost-effective catalysts for scarce and costly metal ones is currently among the major targets of sustainable chemistry. Herein, we report the synthesis of N-, S-, and P-tridoped worst-weed-derived carbon nanorings (WWCNRs) that can serve as a metal-free and selective electrocatalyst for the oxygen reduction reaction (ORR). The WWCNRs are synthesized via activation-free polymerization of worst weed, Eclipta prostrata, and then removal of the metallic residues by using HCl. The WWCNRs exhibit good catalytic activity towards the 4 electron-transfer ORR with a low onset potential and high kinetic limiting current density, along with high selectivity (introducing CO, the sample loses only <7% of its original activity, in contrast to more than 30% loss of the original activity for 20 wt% Pt/C over 4000 s of the continuous ORR) and long durability (94% of the initial current still persists at the sample electrode compared with a 87% current retention at commercial Pt/C electrodes after 18000 s). The present work highlights the smart transformation of organic-rich worst weed into value-added functional materials with great potential for applications such as fuel cells, lithium–air batteries, photocatalysis, and heterocatalysis.

The urgent need for sustainable energy development depends on the progress of green technologies, which have steered hot research areas into environmentally benign approaches via inexpensive precursors and abundant resources obtained directly from nature for energy devices such as fuel cells and supercapacitors. By using fermented rice as starting materials, we herein demonstrate a facile, green and scalable approach to synthesize porous N-doped carbon spheres characterised by high specific surface areas (2105.9 m2 g−1) and high porosity (1.14 cm3 g−1), which exhibit not only excellent electrocatalytic activity toward the four-electron oxygen reduction reaction with long-term stability for fuel cells, but also have excellent resistance to crossover effects and CO poisoning superior to that of the commercial Pt/C catalyst. Furthermore, the naturally derived porous N-doped carbon spheres, used as the active electrode materials, present superior performance for capacitors with a capacitance of 219 F g−1 at a high discharge current density of 15 A g−1 and good cycling stability for over 4400 cycles. This work shows a good example for taking advantage of the abundant resources provided by nature, and opening the door for the creation of functional materials with promising applications in high-performance renewable devices related to energy conversion and storage.

Three-dimensionally (3D) hierarchical micro/nano oriented arrays constructed from nanometer-sized building blocks represent an important group of materials and have received enormous attention for a series of applications because they can offer both the advantages of nanosized building blocks and micro- or submicrometer-sized ordered arrays. In this work, 3D flower-like superhydrophilic CuO micro/nanostructures decorated by Ag nanoparticles were synthesized via an amino acid-assisted biomimetic hydrothermal method. Experiments reveal that the product demonstrates excellent sunlight self-cleaning performance in terms of wettability (without the help of high-free-energy compounds and in the absence of UV irradiation) and enhanced photocatalytic activities, which portends a bright future for this material as self-cleaning photovoltaic coatings. It is also a good example for the organic combination of green chemistry and functional materials.

A green strategy has been developed for synthesizing nitrogen-doped carbon dots (N-CDs) via hydrothermal treatment of willow leaves. The supernatant exhibits strong blue fluorescence under UV radiation and can be directly used as a fluorescent ink, while the solid product with pyrolysis possesses excellent electrocatalytic activity for a highly efficient oxygen reduction reaction with great stability and methanol/CO tolerance superior to a commercial Pt/C catalyst.

Besides a lack of low-cost electrode materials, the match between the electrode materials and electrolytes is one of the top issues to achieve high-rate electrochemical supercapacitors. Herein, we report an environmentally friendly strategy to prepare three-dimensionally interconnected carbon nanorings (TDICNs) from biomass waste, batata leaves and stalks (BLS). The microstructure of TDICNs matches well with acidic and alkaline electrolytes, making them exhibit high specific capacitances of 532.5 F g−1 (1 A g−1) and 264.0 F g−1 (30 A g−1), excellent capacitance retention (95.1% and 91.7% after 1000 cycles at 1 A g−1 and 10000 cycles at 30 A g−1, respectively) and a high energy density of 25.8–11.9 W h kg−1 with a power density of 249.5–13068.0 W kg−1 in 1 mol L−1 H2SO4 aqueous electrolyte. In 6 mol L−1 KOH electrolyte, they still exhibit high specific capacitances of 350.0 F g−1 (1 A g−1) and 246.9 F g−1 (30 A g−1), excellent cycling stability (95.06% and 91.1% of capacitance retention after 1000 (1 A g−1) and 10000 (30 A g−1) cycles, respectively), a high energy density of 24.5 W h kg−1 and a power density of 12918.0 W kg−1.

Fuel cells are promising candidates for clean and high-efficient energy conversion in the future. The development of carbon-based inexpensive metal-free ORR catalysts has become one of the most attractive topics in the fuel cell field. Herein, we report a N-doped carbon catalyst with a surface area of up to 1895.5 m2 g−1 using a natural product (bamboo fungus) as the starting material. In 0.1 M KOH electrolyte, the ORR onset potential for the catalyst is high up to 0.089 V vs. Ag/AgCl. Moreover, it shows superior stability, fuel crossover resistance, and selective activity to a commercial Pt/C catalyst. In addition, the sample displays excellent stability, i.e. no obvious decrease in current was observed after 1000 continuous cycles between −0.7 and 0.3 V in O2-saturated 0.1 M KOH. Moreover, both the structural characterizations and electrochemical tests verify that the treatment techniques of biomass have an important impact on the materials.

This paper reports a simple one-step growth of hierarchically micro/nanostructured porous metallic copper microspheres with high yield at room temperature. The key growth strategy is to use phenol and ascorbic acid as porogen and reducing agents, respectively, to induce the growth of the porous hierarchical micro/nanostructure. The samples are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption. It is found that the morphology and structure of the porous Cu microspheres are highly dependent on the phenol added. Compared to the commercial Cu powders and Cu sheets with dense internal structure, hierarchically micro/nanostructured porous metallic copper microspheres show excellent superhydrophilic surface property and much higher catalytic activity for the reduction of 4-nitrophenol, demonstrating the significance of the pore structure of the copper materials. Their potential applications in catalysis for oxygen reduction reaction of fuel cells are also explored. All these features make the as-prepared porous copper microspheres a highly attractive candidate for multi-functional materials.