Self-template Synthesis Research Articles

Facile self-templating synthesis of layered carbon with N, S dual doping for highly efficient sodium storage

Nitrogen and sulfur co-doping is emerging as a promising approach to prominently improve the sodium storage performance of carbonaceous materials. However, poisonous chemicals and rigorous conditions are normally involved in their preparation, especially in the sulfidation process. Therefore, developing novel, facile and eco-friendly approaches to construct nitrogen and sulfur co-doped carbon (NSC) is still challenging. In this work, a facile self-templating synthesis method is reported to allow the simple and green preparation of NSC. Particularly, small-molecule dithiooxamide can be directly converted to NSC through a facile thermal condensation process, serving as precursor, template, and self-doping agent simultaneously. In account of its high ionic and electronic conductivity, increased interlayer spacing, unique layers assembled structure and efficient N, S co-doping, the NSC obtained at 800 °C exhibits excellent sodium storage performances, including prominent reversible capacity (316.1 mAh g−1 at 0.1 A g−1 up to 100 cycles), remarkable rate capability (178.3 mAh g−1 at 3 A g−1), and robust stability upon long-term cycling (213.6 mAh g−1 at 1 A g−1 up to 2000 cycles), rendering itself to be a promising candidate for practical sodium-ion battery.

Self-templating synthesis of hollow NiFe hydroxide nanospheres for efficient oxygen evolution reaction

Hierarchical nanostructure with hollow feature can greatly promote electrocatalytic activity by facilitating the diffusion of active species and accelerating the contact between catalyst and electrolyte. In this paper, we report the preparation of hierarchical hollow NiFe hydroxide nanospheres assembled from ultrathin nanosheets as the OER electrocatalyst via a simple and gentle self-templating strategy, which includes two steps: the synthesis of Ni(OH)2 nanospheres precursor and its further transformation to the final hollow-spheres after the introduction of Fe3+ via a mild hydrothermal method. The hollow NiFe hydroxide nanospheres were proven to be composed of ultrathin nanosheets which formed porous walls. This unique structure achieved numerous mass transfer channels for electrolytes, ideal pathways for ions and electrons, and a high specific surface area, leading to the improved performance for the product during the electrocatalytic reaction. In addition, the charge transfer rate and structural stability of the architecture have been greatly improved after the addition of Fe3+, which guaranteed high electrochemical performance toward OER. The tafel plot for NiFe-190 without any conductive agents is 60 mV dec−1 and the overpotential needed to reach a current density of 10 mA cm−2 is a 270 mV.

NiO nanoparticles decorated hexagonal Nickel-based metal-organic framework: Self-template synthesis and its application in electrochemical energy storage

A one-pot solvothermal strategy and subsequent calcination were proposed for fabricating a composite of NiO nanoparticles on hexagonal Ni-based metal–organic framework (Ni-MOF) (Ni-MOF@NiO). The prepared NiO nanoparticles on the hexagonal Ni-MOF not only improves the electrical conductivity and increases redox active sites, but also prevents the agglomeration of NiO nanoparticles. In particular, highly dispersed and small-sized NiO nanoparticles on the hexagonal Ni-MOF facilitates the migration of electrolyte ions, and the pseudocapacitive performance is evaluated through electrochemical measurements. At 0.5 A g−1, the Ni-MOF@NiO composite shows a specific capacitance of up to 1192.7 F g−1 and a high capacity retention (93.23% over 5000 cycles) in 3 M KOH. Moreover, the Ni-MOF@NiO nanoparticles and activated carbon are assembled into aqueous devices with a maximum energy density of 62.2 Wh kg−1. These results indicate the potential of Ni-MOF@NiO composite as an electrode material for application in supercapacitors. Additionally, the method of synthesizing Ni-MOF@NiO in this study can be used to synthesize other MOF@metal oxide materials for electrochemical energy storage and other related applications.

Self-Template Synthesis of Multiheteroatom Codoped Porous Carbon with Rational Mesoporosity from Traditional Chinese Medicine Dregs for High-Performance Supercapacitors

As a biomass waste of therapy and health care discarded with millions of tons per year in Chinese people’s daily life, traditional Chinese medicine dregs (MDs) are potential “zero-cost”, species-ri...

Self-template synthesis of hierarchically structured Co3O4@NiO bifunctional electrodes for selective nitrate reduction and tetrahydroisoquinolines semi-dehydrogenation

The rational design and synthesis of hierarchically hollow nanostructures with controlled spatial architecture and composition are significant in electrocatalysis owing to their abundant active sites and the expedited electron/mass transfer. Electrocatalytic nitrate reduction to ammonia is of great interest from the points of environmental protection and energy saving. However, the development of this technology is hindered by the lack of efficient nitrate-to-ammonia electrocatalysts and the kinetically sluggish oxygen evolution reaction at the anode. Herein, a novel self-template conversion method was developed for the synthesis of Co3 O4@NiO hierarchical nanotubes (Co3O4@NiO HNTs) with NiO porous nanosheets assembled on Co3O4 nanotubes. The as-obtained Co3O4@NiO HNTs exhibited an outstanding performance for both the cathodic nitrate electroreduction to ammonia reaction and the anodic tetrahydroisoquinolines (THIQs) semi-dehydrogenation to dihydroisoquinolines (DHIQs). Importantly, a two-electrode system of Co3O4@NiO HNTs ∥ Co3O4@NiO HNTs was constructed for the simultaneous synthesis of ammonia and DHIQs with high selectivity and robust stability.

(Invited) Self-Template Synthesis of Atomically Dispersed Fe/N-Codoped Nanocarbon As Efficient Bifunctional Oxygen Electrocatalyst

High performance and durable bifunctional oxygen electrocatalysts are of great importance for the commercial application of environmentally friendly and sustainable energy through electrochemical devices such as rechargeable Zn–air batteries and fuel cells. Highly distributed catalysts with maximum atomic utilization are considered to be a promising alternative for current noble-metal-based catalysts. Herein, a high performance and durable bifunctional oxygen electrocatalyst for both ORR and OER is synthesized by a facile self-template and polypyrrole encapsulation method. The super performance atomically dispersed Fe/N-codoped double shelled hollow carbon nanospheres (AD-Fe/N-C-900) catalyst has a special open porous double shell hollow structure which is beneficial to exposure of more Fe-Nx active sites for ORR and OER, and improves mass transfer, resulting in a fabulous bifunctional ORR/OER electrocatalytic activity (△E =0.655 V), which is better than the commercial Pt/C (△E =1.035 V) and the commercial IrO2 (△E =0.93 V), along with remark durability and long-term stability for the ORR in alkaline medium. Based on our results and analysis, the remarkable electrocatalytic activity of AD-Fe/N-C-900 might be attributed to the high content of mesopore, high density of Fe-Nx active sites, and robust double shell hollow structure. The novel design of the atomically dispersed Fe/N-codoped porous double shell hollow nanocarbon enable boosted oxygen catalyst by a facile method has certain enlightening effect on the design and development of other bifunctional electrocatalysts in the next generation reversible energy conversion systems. Our work provides a design idea for the synthesis of high activity and stability bifunctional atom-level distributed catalysts. Figure 1

Self-Templating Synthesis of Hollow Co3O4 Nanoparticles Embedded in N,S-Dual-Doped Reduced Graphene Oxide for Lithium Ion Batteries

The design and synthesis of hollow-nanostructured transition metal oxide-based anodes is of great importance for long-term operation of lithium ion batteries. Herein, we report a two-step calcination strategy to fabricate hollow Co3O4 nanoparticles embedded in a N,S-co-doped reduced graphene oxide framework. In the first step, core-shell-like Co@Co3O4 embedded in N,S-co-doped reduced graphene oxide is synthesized by pyrolysis of a Co-based metal organic framework/graphene oxide precursor in an inert atmosphere at 800 °C. The designed hollow Co3O4 nanoparticles with an average particle size of 25 nm and wall thickness of about 4-5 nm are formed by a further calcination process in air at 250 °C via the nanoscale Kirkendall effect. Both micropores and mesopores are generated in the HoCo3O4/NS-RGO framework. Benefiting from the hierarchical porous structure of the hollow Co3O4 and the co-doping of nitrogen and sulfur atoms in reduced graphene oxide, the thus-assembled battery exhibits a high specific capacity of 1590 mAh g-1 after 600 charge-discharge cycles at 1 A g-1 and a promising rate performance from 0.2 to 10 A g-1.

Self-template synthesis of nitrogen-doped porous carbon derived from rice husks for the fabrication of high volumetric performance supercapacitors

Abstract Porous carbons (PCs) derived from biomass have been successfully used in the fabrication of supercapacitors as electrode material. Their large surface area and developed porosity significantly contribute to the high gravimetric capacitance, but deteriorate the carbon density leading to low volumetric capacitance. PCs with high volumetric capacitance are more desirable for portable energy storage devices. Herein, high volumetric performance nitrogen-doped PCs were prepared by the pyrolysis of urea-impregnated rice husks. The self-template effect of rice husks created hierarchical porosity for ion storage and transport. The decomposed urea introduced nitrogen-containing groups to generate pesudocapacitance without sacrificing carbon density. As a result, the resultant product 4NPC-800 exhibited high volumetric capacitance of 306 F cm−3 at 0.5 A g−1 in 1 M H2SO4 electrolyte. The assembled symmetric supercapacitor presented a superior volumetric energy density of 15.24 W h L−1 at 594 W L−1 and outstanding cycling stability. The favorable capacitive behavior of 4NPC-800 demonstrated its potential as carbon-based electrode applied in high performance supercapacitors.

Phytic acid-assisted self-templating synthesis of N-P-Fe-tridoped hierarchical porous carbon for efficient oxygen reduction reaction

Developing efficient, stable and non-precious metal alternatives to platinum-based catalysts for oxygen reduction reaction (ORR) is significant for many energy conversion devices. Herein, we report a phytic acid-assisted self-templating strategy to fabricate N–P–Fe-tridoped carbon with a hierarchical porosity. The resultant unique structures and well-designed heteroatoms-doping condition impart final catalysts with enhanced mass transfer ability and abundant available active-sites, ensuring high performance in catalyzing ORR. Impressively, the half wave potential of the optimal catalyst is 0.926 V (vs. RHE), which is 40 mV higher than the state-of-art platinum-based catalyst and better than most reported ORR catalysts. Significantly, when applied to a primary Zn–O2 battery, our catalyst comprehensively outperforms the commercial Pt/C catalyst whether on power density or specific capacity.

Hydrothermally self-templated synthesis of rectangular polyimide submicrotubes and promising potentials in electrochemical energy storage

An unconventional hydrothermal polycondensation of monomer salt crystals was readily performed to produce rectangular-shape amorphous polyimide submicrotubes, which show promising potentials in serving as both cathode and anode active materials for Li-ion batteries as well as being transformed into N-doped carbon tubes for supercapacitor electrodes.

Facile self-templating synthesis of heteroatom-doped 3D porous carbon materials from waste biomass for supercapacitors.

Heteroatom-doped 3D porous carbon materials have been synthesized by utilizing hydroxyapatite in pig bones as a self-template and used as electrode materials for symmetric supercapacitors, which exhibit ultra-high energy density both in an aqueous electrolyte and organic electrolyte, showing great potential applications in the next generation of energy storage and conversion devices.

Controlled self-template synthesis of manganese-based cuprous oxide nanoplates towards improved fire safety properties of epoxy composites

To date epoxy resins have been extensively used in the field of chemical engineering, aerospace and building materials. Nevertheless, the utilization of flammable epoxy resins has posed a huge threat to lives and properties, which restricted their applications. In this work, manganese-based cuprous oxides two-dimensional nanosheets (Mn@Cu2O-M) are rationally designed and successfully prepared to improve the toxic effluent elimination of epoxy resin. The fire safety properties of the prepared Mn@Cu2O-M based nanocomposites improved the heat release rate (<35 %) and total heat release (<40 %) compared to the control epoxy. Moreover, the production of smoke and toxic volatiles of the composites with Mn@Cu2O-M nanosheets is significantly reduced. The mechanism investigations indicate that the improved flame retardancy and toxic effluent elimination of epoxy composites are attributed to the physical barrier effect and catalytic carbonization awarded by Mn@Cu2O-M nanosheets during burning. This work provides a promising strategy to develop eco-friendly, efficient and fire-safe polymers by both physical barrier effect and catalytic carbonization.

Self-Template Synthesis of Atomically Dispersed Fe/N-Codoped Nanocarbon as Efficient Bifunctional Alkaline Oxygen Electrocatalyst

High performance and durable bifunctional oxygen electrocatalysts are of great importance for the commercial application of environmentally friendly and sustainable energy through electrochemical d...

Self-template synthesis of ZnS/Ni3S2 as advanced electrode material for hybrid supercapacitors

In this work, ZnS/Ni3S2 electrode material was synthesized by a simple self-template approach. The synthetic route includes chemical precipitation of Zn–Ni precursor in a polyvinylpyrrolidone (PVP)/Milli-Q water solution by dropping ammonia solution and subsequent conversion of the Zn–Ni precursor to ZnS/Ni3S2via chemical reaction with thioacetamide (TAA), as the sulfur source. Here, the Zn–Ni precursor can be considered as a template that is converted to ZnS/Ni3S2 during the sulfidation process. The synthesized ZnS/Ni3S2 material displays a porous texture and a high specific surface area. These properties are beneficial for the investigation of the developed material as electrode in supercapacitors. Indeed, the obtained ZnS/Ni3S2 material exhibits improved specific capacity of 890.1 C g−1 at 1 A g−1 along with a good rate capability (70% retention of its initial value from 1 A g−1 to 20 A g−1). Furthermore, the ZnS/Ni3S2 electrode achieves a good cycling stability (∼82% retention of its capacity at 10 A g−1 after 6000 charging-discharging cycles). Moreover, ZnS/Ni3S2 is used as a positive electrode and porous reduced graphene oxide (PrGO) as a negative electrode to assemble a hybrid supercapacitor. The fabricated hybrid supercapacitor offers a specific capacity of ∼112.5 C g−1 at 0.5 A g−1, and delivers an energy density of 30.6 W h kg−1 at a power density of 880 W kg−1. This work not only demonstrates that ZnS/Ni3S2 material can serve as an efficient electrode material for supercapacitors, but also provides an easy operation way for preparing high performance metal-sulfide electrodes for energy storage application.

Self-templating synthesis of carbon-encapsulated SnO2 hollow spheres: A promising anode material for lithium-ion batteries

Carbon-encapsulated SnO2 hollow spheres were fabricated by a self-templating method from Sn spheres for lithium-ion batteries (LIBs). High-temperature annealing (e.g., 700 °C) inevitably led to the formation of Sn on the exterior surface, which was disadvantageous for long-term cycling. In contrast, the preparation at an optimal annealing temperature of 600 °C coupled with subsequent acid etching completely encapsulated the SnO2 within a carbon shell while maintaining a stable hollow structure. The as-prepared carbon-encapsulated SnO2 hollow spheres after acid etching (SnO2@C–6H) exhibited enhanced electrochemical performance for LIBs characterized by high cycling stability and rate capacity. Specifically, SnO2@C–6H displayed a reversible capacity of 897.9 mA h g−1 at 200 mA g−1 after 120 cycles and a promising rate capacity of 549.8 mA h g−1 at a high current density of up to 2000 mA g−1. The obtained high-performance could be attributed to the formation of a unique hollow structure with an enlarged specific surface area of 215.18 m2 g−1 and a relatively high degree of graphitization (i.e., ID/IG = 0.84) of the carbon shell. A plausible cause for this performance was that the acquired hollow spheres not only provide a barrier effect for volume expansion and the aggregation of SnO2, but also promote lithium storage.

Commercial-Level Energy Storage via Free-Standing Stacking Electrodes

Summary Pseudocapacitors with a fast faradic redox reaction during the electrochemical charge/discharge process hold great promise for delivering high power and high energy. Here, we used emerging oxygenated carbon nitride (OCN) as a model for nitrogen- and oxygen-enriched carbons and found an anion-selective charging behavior in aqueous electrolytes. The N- and O-mediated hydroxyl anion-selective charging originates from inbuilt surface-positive electrostatic potential localized at heptazine and quaternary N atom structural units. The carbon atoms in heptazine adjacent to pyridinic N act as the electron transfer active sites for faradic pseudocapacitance. The OCN free-standing films (FSFs) were developed as current collector-free electrodes, and stacking OCN FSFs can confer a cell with loading weight over a commercial level. For demonstration, a symmetrical cell with 17.7 mg cm−2 delivers an energy of 140.9 mW h at a high power of 2,499.9 mW, and almost 100% capacitance retention after 20,000 charge/discharge cycles at 50 mA.

Self-templated synthesis of an orthoformate in,in-cryptand and its bridgehead inversion by dynamic covalent exchange

Self-templated synthesis of an orthoformate in,in-cryptand and its bridgehead inversion by dynamic covalent exchange

Large-scale self-template synthesis of NiCo2O4 nanotubes derived from alginate for high-rate lithium storage properties stimulated by capacitive effects

Searching high-rate and long-life electrode material of transition metal oxides is still considered a prospective choice to boost powerful electrochemical energy conversion and storage application. Herein, NiCo2O4 nanotubes have been fabricated in large quantities by a facile self-template formation strategy using alginate. Such an interesting nanostructure owns optimal voids inside the stable shells, which can facilitate the fast ion diffusion and efficiently buffer the huge volume changes when used as an anode material for lithium ion batteries. As a result, the as-synthesized NiCo2O4 nanotubes electrode delivers admirable electrochemical properties with high reversible capacity (1162 mAh g−1 in the initial cycle at 0.2 A g−1), excellent cycling stability (949 mAh g−1 after 800 cycles at 1 A g−1) and especially remarkable rate capability (684 mAh g−1 even at 8 A g−1). The present work may demonstrate great potential in the large-scale preparation of the NiCo2O4 nanotubes for advanced lithium storage.

Self-Template Synthesis of Nanoporous VO2-Based Films: Localized Surface Plasmon Resonance and Enhanced Optical Performance for Solar Glazing Application.

Poly(tetrafluoroethylene) (Teflon) has been selected as the self-template structural material in the preparation of VO2 films using a reactive magnetron sputtering method and post-annealing process. VO2 films with spontaneous random nanoporous structures growing on quartz glasses have been deliberately established via bottom-up processing through this novel and facile approach. The nanoporous VO2 films exhibit an excellent optical performance based on the localized surface plasmon resonance, with ultrahigh luminous transmittance ( Tlum-L) up to 78.0% and the promoted solar modulation ability (Δ Tsol) of 14.1%. Meanwhile, the ingenious microstructure of the film provides an antireflection function from multiple perspectives on visible light and indicates the potential of the windshield on vehicles for smart solar modulation. The nanoporous films expand the practical application of thermochromic VO2 to a fire-new field, breaking the optical performance envelope of the single-layer dense VO2 film away, and offering a universal method to prepare homogeneous nanoporous structures for thin films.

Highly efficient self-template synthesis of porous silica nanorods from natural palygorskite

A simple one-step hydrothermal acid-leaching process was employed to efficiently convert natural Pal to porous silica nanorods with a high SiO2 content and decent length of nanorods. At a lower acid concentration (2.0 mol/L), silica nanorods with the SiO2 content of 97.84% and a rod length equal to original length of Pal nanorods were obtained by this process; while only the products with lower SiO2 content of 79.92% were obtained by a normal acid-bleaching process. Although increasing acid concentration to 8.0 mol/L may enhance SiO2 content to 94.56% in normal acid-leaching process, which led to sharp reduction of length of nanorod. The synthesized porous silica nanorods have a specific surface area of 119.39 m2/g, average pore size of 7.56 nm, and better whiteness (the L*, a* and b* values are 86.130, 0.131 and 2.801, respectively). This paper provided an effective, universal approach to produce silica nanomaterials from diverse natural clay minerals.