Self-template Synthesis Research Articles

Self-Templating Synthesis of Mesoporous Carbon Cathode Materials for High-Performance Lithium-Ion Capacitors.

Lithium-ion capacitors (LICs) have attracted considerable interest because of their excellent power and energy densities. However, the development of LICs is limited by the low capacity of the cathode and the kinetics mismatch between the cathode and anode. In this work, mesoporous carbon materials (MCs) with uniform pore sizes were prepared using magnesium citrate as the raw material through a self-templating method. During the carbonization process, MgO nanoparticles generated from magnesium citrate act as a template, resulting in a more orderly pore structure. The resultant MCs demonstrate a high specific surface area of 1673 m2 g-1 and an abundance of small mesopores, which significantly accelerated ion migration within the electrolyte and expedited the formation of electric double layers. Benefiting from these advantages, the MCs cathode demonstrates a high reversible specific capacity, excellent cycling stability, and rate performance. The assembled MCs-based LIC provides a high energy density of 152.2 Wh kg-1 and a high power density of 14.3 kW kg-1. After 5000 cycles, a capacity retention rate of 80 % at the current density of 1 A g-1 is obtained. These results highlight the excellent potential of MCs as a cathode material for LICs.

Green self-templated synthesis of P-doped mesoporous carbon from dual sodium salts with improved average pore size for capacitive deionization

Mesoporous carbon materials hold significant potential in capacitive deionization (CDI) technology owing to expansive accessible surface area, more adaptable pore structure, excellent conductivity properties and effective surface modification and functionalization. While templating is a common method for synthesizing mesoporous carbons, the commonly used hard and soft templating approaches among them suffer from the challenges of expensive precursors and templating agents, complex procedures, secondary contaminants and difficulties in template removal. In contrast, the self-templating method not only circumvents the traditional template removal or combustion steps but also eliminates the use of organic solvents and hazardous chemicals, thus minimizing environmental impact. In this paper, we have successfully synthesized phosphorus-doped mesoporous carbon with a large average pore size (paver) using a green and convenient self-templating method employing dual sodium salts of sodium alginate (SA) and sodium phytate (SP). Compared to single SA (6.76 nm) or SP (3.74 nm) self-templated carbonization, the average pore size of carbon materials obtained from dual self-templated carbonization with a proportional mixture (12.97 nm) is significantly improved. The larger average pore size provides a greater surface area for electrode-electrolyte interactions, allowing for easier access and faster diffusion of ions into the pores, thereby enhancing the electrochemical and capacitive deionization properties of the material. The resulting material demonstrates promising electrochemical and desalination performance as evidenced by possessing a specific capacitance of 175.8 A/g and an adsorption capacity of 19.65 mg/g, underlining its potential for application in capacitive deionization utilizing mesoporous carbon materials with large average pore size.

A controllable self-template synthesis strategy for hierarchical porous carbon microspheres with cavity structures for supercapacitor applications

Herein, we introduce a novel and controllable self-template approach for fabricating hierarchical porous carbon microspheres with cavities (CPCMs). This approach uses polyacrylonitrile (PAN) and acrylamide (AM) microspheres as templates, which feature small anisotropic bumps on their surface. These bumps are encapsulated by divinylbenzene (DVB) during the coating polymerization process. The subsequent hydrolysis of PAN and AM led to the formation of a hierarchical porous structure. Specifically, mesopores mainly arose from PAN hydrolysis, whereas AM contributed additional micropores and macropores, generating an intricate pore structure within the DVB shell. This method differs from traditional pore-making approaches. Additionally, in situ doping of nitrogen (N) and oxygen (O) atoms was achieved. The amount of DVB coating can be adjusted to vary the shell thickness, allowing for the modulation of the pore size distribution and surface micromorphology. Owing to the synergistic effects of an ultrahigh specific surface area (1151.9 m2 g−1), extensive pore volume (1.2575 m3 g−1), and well-structured micro-meso-macropore hierarchy, along with N/O codoping, the resulting carbon material exhibited outstanding electrochemical energy storage performance. Notably, the optimal CPCMs-2 electrode achieves an exceptional specific capacitance of 377 F g−1 at a current density of 0.5 A g−1. This study proposes a novel avenue for designing hierarchical porous carbon materials, and CPCMs could be expanded to a wide range of applications.

Nanoporous carbon materials: modern production methods and applications

The review presents data on the nomenclature and production methods of the most intensively investigated classes of nanoporous carbon materials, which are increasingly used in science, medicine, and various fields of economy. The traditional activated carbons, which are produced by conventional biomass and fossil hydrocarbon processing methods, are compared with nanoporous carbon materials obtained using modern synthetic methods. Recommendations are given on the use of template synthesis to obtain carbon materials with a controlled nanoporosity. Self-template synthesis, in which environmentally benign and readily available organic salts can be used as precursors, is considered as a promising avenue of research. This approach markedly reduces the cost of template synthesis of nanoporous carbons and allows for the preparation of carbon materials with specific particle morphology from organometallic precursors. Methods for the preparation of functional materials with ordered architectures of micro- and mesopores are considered, including modern functionalization and doping approaches. A part of the review is devoted to advanced applications of nanoporous carbon materials such as water treatment, energy and hydrogen storage, separation of gas mixtures, development of catalysts and sensors, and solution of other significant problems. The conclusion summarizes the experience of application of various methods for the preparation of nanoporous carbon materials, identifies the most problematic issues of the development and practical use of these materials, and presents the authors' view on further development of this area of materials science.<br> The bliography includes 353 references.

Self-template synthesis of pitch-based hierarchical porous carbon for high performance supercapacitor in aqueous and ionic liquid electrolytes

Pitch-based hierarchical porous carbons (PHPCs) have been fabricated by means of self-templated method that is adopting metal oxides and metallic salts impurities originate from coal tar pitch (CTP) precursor serve as in-situ hard template along with KOH activation. The porosity properties of PHPCs are significantly influenced by the mass ratio of KOH to pitch. The micro-morphology, hierarchical porosity constituted of co-existing micro-/meso-/macropores, specific surface area, surface elementary composition and electrochemical properties have been comprehensively investigated. It is shown that the high specific surface area (2479 m2 g-1), lay-stacked microstructure, hierarchical porosity characteristic and considerable oxygen-containing functional groups (4.51 a.t %) that synergistically facilitate the electrochemical performance of PHPCs. The electrochemical measurements results exhibit that the gravimetric capacitance for the optimal sample PHPCs-4 is as high as 317 F g-1 at a current density of 0.2 A g-1, with retention of 213 F g-1 even at 10 A g-1 in a three-electrode configuration. In a two-electrode device, the PHPCs-4 based symmetric supercapacitor cell exhibits a specific capacitance of 245 F g-1 at 0.1 A g-1, along with a good rate capability of 75.5% (185 F g-1 at 10 A g-1) and a considerable energy density of 8.51Wh kg-1 at a power density of 50 W kg-1. When tested in EMIMBF4 ionic liquid electrolyte at a cell voltage of 3.5 V, the assembled symmetric supercapacitor cell demonstrates a high energy density of 77 Wh kg-1 at a power density of 175 W kg-1, maintaining 65.3 Wh kg-1 at a current density of 1 A g-1, and 32.1 Wh kg-1 at a high power density of 17500 W kg-1. Furthermore, the specific capacitance of the PHPCs-4 based symmetric supercapacitor retains nearly 100% of its initial value over 5000 cycles in 6M KOH aqueous electrolyte and 91.4 % after 2500 cycles in EMIMBF4 ionic liquid electrolyte. This strategy exploits a novel approach to synthesizing hierarchical porous carbons from coal tar pitch using a self-templating method, offering potential benefits for various applications.

Self-templating synthesis strategy of oxygen-doped carbon from unique wasted pulping liquid directly as a cathode material for high-performance zinc ion hybrid capacitors

Affinity and storage capacity for zinc ions of the electrode materials are crucial factors on the properties of zinc ion hybrid capacitors (ZHICs). Wasted pulping liquor with abundant carbohydrates, lignin and inorganic matter served as a unique precursor to produce embedded oxygen-doped hierarchical porous carbon directly through a one-step carbonization process in this investigation. In carbonization process, lignin can serve effectively as the carbon framework, carbohydrates not only act as sacrificial templates but also offer a plentiful oxygen source which can increase the affinity for Zn2+, and sodium-containing inorganic substances plays a role as hard templates to optimize the pore structure. The resulting porous carbon under carbonization temperature of 800 °C shows a high specifical area of 2186 m2g−1 with oxygen content of 4.8 %, which can reduce the adsorption energy of Zn2+ from −0.16 eV to −0.32 eV through electrochemical techniques and density functional theory (DFT) calculations, the incorporation of oxygen was demonstrated to enhance the adsorption and desorption kinetics of Zn2+, suggesting a bright future for application in the domain of energy storage. The resulting ZIHC assembly showcases a notable energy density of 84.6 Wh kg−1 at a power density of 359 W kg−1. Remarkably, even after 10,000 charge and discharge cycles, it exhibits exceptional cycle stability with retaining 86.56 % of its capacity. Consequently, this approach provides fresh insights for exploring the facile and commercial fabrication of biomass-derived cathodes for ZIHCs, thereby propelling the progress of eco-friendly energy storage devices.

Engineering of heterointerface of ultrathin carbon nanosheet-supported CoN/MnO enhances oxygen electrocatalysis for rechargeable Zn–air batteries

Designing bifunctional electrocatalysts with outstanding reactivity and durability towards the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has remained a long-term aim for metal-air batteries. Achieving the high level of fusion between two distinct metal components to form bifunctional catalysts with optimized heterointerfaces and well-defined morphology holds noteworthy implications in the enhancement of electrocatalytic activity yet challenging. Herein, the fabrication of numerous heterointerfaces of CoN/MnO is successfully realized within ultrathin carbon nanosheets via a feasible self-templating synthesis strategy. Experimental results and theoretic calculations verify that the interfacial electron transfer from CoN to MnO at the heterointerface engenders an ameliorated charge transfer velocity, finely tuned energy barriers concerning reaction intermediates and ultimately accelerated reaction kinetics. The as-prepared CoN/MnO@NC demonstrates exceptional bifunctional catalytic performance, excelling in both OER and ORR showcasing a low reversible overpotential of 0.69 V. Furthermore, rechargeable liquid and quasi-solid-state flexible Zn-air batteries employing CoN/MnO@NC as the air-cathode deliver remarkable endurance and elevated power density, registering values of 153 and 116 mW cm−2 respectively and exceeding Pt/C + RuO2 counterparts and those reported in literature. Deeply exploring the effect of electron-accumulated heterointerfaces on catalytic activity would contribute wisdom to the development of bifunctional electrocatalysts for rechargeable metal-air batteries.

Self-templating synthesis of biomass-based porous carbon nanotubes for energy storage and catalytic degradation applications

Dwindling energy sources and a worsening environment are huge global problems, and biomass wastes are an under-exploited source of material for both energy and material generation. Herein, self-template decoction dregs of Ganoderma lucidum-derived porous carbon nanotubes (ST-DDLGCs) were synthesized via a facile and scalable strategy in response to these challenges. ST-DDLGCs exhibited a large surface area (1731.51 m2 g−1) and high pore volume (0.76 cm3 g−1), due to the interlacing tubular structures of precursors and extra-hierarchical porous structures on tube walls. In the ST-DDLGC/PMS system, the degradation efficiency of capecitabine (CAP) reached ∼97.3% within 120 min. Moreover, ST-DDLGCs displayed high catalytic activity over a wide pH range of 3–9, and strong anti-interference to these typical and ubiquitous anions in wastewater and natural water bodies (i.e., H2PO4−, NO3−, Cl− and HCO3−), in which a 1O2-dominated oxidation was identified and non-radical mechanisms were deduced. Additionally, ST-DDLGC-based coin-type symmetrical supercapacitors exhibited outstanding electrochemical performance, with specific capacitances of up to 328.1 F g−1 at 0.5 A g−1, and cycling stability of up to 98.6% after 10,000 cycles at a current density of 2 A g−1. The superior properties of ST-DDLGCs could be attributed to the unique porous tubular structure, which facilitated mass transfer and presented numerous active sites. The results highlight ST-DDLGCs as a potential candidate for constructing inexpensive and advanced environmentally functional materials and energy storage devices.

Self-template synthesis of hollow flower-like NiCo2O4 nanoparticles as an efficient bifunctional catalyst for oxygen reduction and oxygen evolution in alkaline media

Abstract A method was proposed to synthesize hollow flower-like NiCo2O4 composed of porous nanosheets using a self-template approach. The unique structure is attributed to the synergistic effect of the Kirkendall effect and the Ostwald ripening mechanism. The sheet-like and porous structure endowed the material with a specific surface area of 137.1 m2 g−1 and a pore volume of 0.418 cm3 g−1. The distinctive structure and high-density active sites imparted excellent catalytic performance in oxygen reduction (ORR) and oxygen evolution (OER) reactions. Electrochemical tests showed that the limit current density of ORR reached 5.58 mA cm−2, comparable to that of the noble metal Pt/C (20 wt%). The overpotential of OER at a current density of 10 mA cm−2 was only 380 mV, significantly lower than that of the noble metal RuO2. These results indicate that the synthesized hollow flower-like NiCo2O4 has the potential to replace noble metals in ORR and OER catalytic applications.

Self-template synthesis of mesoporous and biodegradable Fe3O4 nanospheres as multifunctional nanoplatform for cancer therapy

Superparamagnetic Fe3O4 nanospheres have demonstrated great potential as important components in nanomedicine for cancer imaging and therapy. One of the major obstacles that impedes their application is the slow degradation of ingested Fe3O4 nanospheres, which potentially causes long-term health risks. To tackle this issue, we proposed to fabricate Fe3O4 nanospheres with mesoporous structure via a simple self-template etching method. The mesoporous Fe3O4 nanospheres not only offered large specific surface area and weak-acidic responsive degradability, but also exhibited T2-weighted magnetic resonance contrast enhancement and magnetic targeting, which made them possible to serve as excellent cancer therapeutic nanoplatform. Both inorganic photothermal therapeutic Au nanoparticles and organic chemotherapeutic doxorubicin hydrochloride were demonstrated to be successfully loaded onto such kind of nanoplatform, and the hybrid nanomedicine demonstrated synergistic photothermal and chemotherapeutic activity for tumor elimination under near infrared irradiation and improved biodegradability in weak acidic tumor microenvironment. We believe that this study paved a simple way for designing multifunctional Fe3O4-based biodegradable nanomedicine.

Reversible active bridging sulfur sites grafted on Ni3S2 nanobelt arrays for efficient hydrogen evolution reaction

Elaborate and rational design of cost-effective and high-efficiency non-noble metal electrocatalysts for pushing forward the sustainable hydrogen fuel production is of great significance. Herein, a novel VS4 nanoparticle decorated Ni3S2 nanobelt array in-situ grown on nickel foam (VS4/Ni3S2/NF NBs) was prepared by a self-templated synthesis strategy. Benefitting from the unique nanobelt array structure, abundant highly active bridge S22- sites and strong electronic interaction between VS4 and Ni3S2 on the heterointerface, the integrated VS4/Ni3S2/NF NBs exhibited excellent electrocatalytic hydrogen evolution activity and robust stability. The density functional theory (DFT) further revealed the reversible conversion catalysis mechanism of bridging S22- sites in VS4/Ni3S2/NF NBs during HER process. Notably, bidentate bridging SS bonds as the predominant catalytically active centers can spontaneously open once H adsorbed its surface, leading to the aggregation of negative charges on S atoms and thus facilitating the generation of H* intermediates, and spontaneously close when H* desorption is going to form H2. Our work provides fresh insights for developing potential polysulfides as high-performance hydrogen-evolving electrocatalysts for prospective clean energy production from water splitting.

Self-template synthesis of Fe–Nx doped porous carbon as efficient oxygen reduction reaction catalysts in zinc air batteries

Metal-nitrogen doped carbon materials (M/NCs) exhibit considerable potential as electrocatalysts for oxygen reduction reaction (ORR) in novel energy conversion and storage devices. Herein, the Fe–Nx doped porous carbon catalysts (FeNxPCs) with three-dimensional (3D) pore structure are synthesized by in situ pyrolyzation of polypyrrole-coated Fe2O3 (Fe2O3@PPy). Fe2O3 derived from the iron-formate framework (Fe-FF) is partially dissolved to generate Fe3+ for driving polymerization and served as template to form the 3D structure during polymerization. FeNxPCs exhibit satisfactory long-term durability and superior ORR activity (E1/2 = 0.89 V) compared to commercial Pt/C. The Zn-air battery (ZAB) assembled with FeNxPCs reveals excellent battery performance, including a high open circuit voltage of 1.50 V, peak power density of 155.4 mW cm−2, and cycling stability with 500 cycles. The excellent ORR activity of FeNxPCs could be ascribed to the porous structure, Fe–Nx active sites, and high defect level of FeNxPCs. This strategy can modulate 3D porous structure via self-template synthesis, which provides a novel insight for development of high-performance air cathode catalyst.

Self-template synthesis of CuCo2O4 nanosheet-based nanotube sorbent for efficient Hg0 removal

Adsorption method is an effective way to remove Hg0 from flue gas, and the morphology and active site of sorbents seriously affect the Hg0 removal efficiency. The hierarchical porous nanosheet-based nanotube structure can effectively reduce the mass transfer resistance and provide more active sites. Inspired by this, the organic-inorganic hybrid nanowires of Co-aspartic acid was used as the template, which can hydrolyze in water-alcohol mixed solution and coordinate with Cu2+ based on Kirkendall effect to prepare nanosheet-based nanotube of CuCo2O4 sorbents. By changing the ratio of water to alcohol, the hydrolysis rate of Co-aspartic acid nanowires will be changed resulting in different physicochemical properties for CuCo2O4 sorbents. Characterization results show that when the ratio is 1:2, the sorbent (CuCo2O4-1-2) has the best hierarchical porous nanosheet-based nanotube structure and the best redox properties. CuCo2O4-1-2, which has the widest reaction temperature window, has a high Hg0 removal efficiency of 89 % under a high GHSV of 180 000 h−1 at 250 °C and a good poisoning resistance and stability. The straight nanotube can effectively reduce the gas transfer mass resistance, and the mesoporous nanosheets structure on its surface provide more active sites for the reaction, which improves the ability of CuCo2O4-1-2 sorbent to capture and activate O2. Meanwhile, DFT calculation shows Cu-Co on the surface of CuCo2O4 is the main active site because the bond length of OO can be effectively lengthened when O2 is adsorbed on the Cu-Co site.

Self-templating synthesis and photocatalytic activity of hollow TiO2 microspheres prepared by the sol–gel + solvothermal method

The microstructure of TiO2 hollow microspheres has a significant impact on the photocatalytic activity, especially the diameter, thickness, specific surface area and crystallinity, which are key factors for structure regulation. In this study, a self-template synthesis strategy for preparing hollow TiO2 hydrate microspheres by the sol–gel+ (methanol) solvothermal method was proposed. With the increase of the H2O/TBOT molar ratio (Rw) in the range of 0.75 ∼ 3.75, amorphous TiO2 colloidal microspheres with flower-like, hollow and solid structures of different sizes were prepared, and the control of TiO2 hydrate hollow microsphere diameters in the range of 1000 nm ∼ 1800 nm was realized. After calcination at 600 °C for 2 h, the structure was not damaged and had good crystallinity. TiO2 hollow spheres of Rw = 1.5 were used for ultraviolet photocatalytic degradation of 20 mg·L-1 phenol for 120 min, and the mineralization rate was >99%, which was better than P25. A series of analyses shows that under the experimental conditions, the hydrolysis rate can be controlled by regulating the H2O/TBOT molar ratio, which is the key factor in the synthesis of different structural sizes.

Self-Templated Synthesis of Triphenylene-Based Uniform Hollow Spherical Two-Dimensional Covalent Organic Frameworks for Drug Delivery

Constructing two-dimensional covalent organic frameworks (2DCOFs) with a desirable crystalline structure and morphology is promising but remains a significant challenge. Herein, we report self-templated synthesis of uniform hollow spherical 2DCOFs based on 2,3,6,7,10,11-hexakis(4-aminophenyl) triphenylene. A detailed time-dependent study of hollow sphere formation reveals an intriguing transformation from initial homogeneous solid spheres into uniform hollow spheres with the Ostwald ripening mechanism. Impressively, the resultant spherical 2DCOFs are composed of high crystallinity nanosheets and even hexagonal single crystals, as demonstrated by transmission electron microscopy. Thanks to its uniform morphology and high crystallinity, the pore volume of the obtained 2DCOFs is up to 1.947 cm3 g–1, which makes it function as superior nanocarriers for efficient controlled drug delivery. This result provides an avenue for improving COFs’ performance by regulating their morphology.

Facile one step self-template synthesis of NixMgMn2O4 (X= 0.12 to 0.50) alloys as a promising cathode for magnesium ion battery

Magnesium-ion batteries (MIBs) are one of the main candidates in the new generation of batteries beyond lithium-ion batteries, but their main limitation is in their cathodes. In this study, the performance of MgMn2O4 spinel and different percentages of nickel doping are investigated to find the optimal value for the preparation of the best cathode for magnesium-ion batteries. Structural studies are performed by various techniques, including morphological studies using FE-SEM, crystal studies using X-ray diffraction and Raman spectroscopy to confirm the accuracy of the synthesis and the effects of nickel on the amount of network strains that are directly related to structural stability. In addition, the electrochemical performance of all samples is evaluated, and the results show that the capacity is 148.56, 164.66 mA h g−1 at a current density of 500 mA g−1 for MgMn2O4, MgMn2O4@Ni0.25, respectively, which is obtained after 250 cycles of 70 and 94.44 mA h g−1. Moreover, the cyclic voltammetry of the samples is investigated. Amongst the nickel-doped samples, the sample with a content of 0.25% had a better performance. The optimum amount of nickel doping in MgMn2O4 spinel is 0.25%, which is been able to achieve structural stability to a satisfactory degree.

Self-templated synthesis of novel and robust honeycomb-like N-doped highly graphitized carbon from low-temperature carbonization

Honeycomb-like N-doped highly graphitized carbon is prepared by self-templated magnesiothermic reduction. Porosity and graphiticity of the prepared carbon support greatly improve the catalytic performance and durability of PtCo alloy in PEMFCs.

A strategy of making waste profitable: Self-templated synthesis of helical rod structured porous carbon derived from Ganoderma Lucidem for advanced supercapacitor electrode

A strategy of making waste profitable: Self-templated synthesis of helical rod structured porous carbon derived from Ganoderma Lucidem for advanced supercapacitor electrode

Synthesis of Mesoporous Ag2O/SnO2 Nanospheres for Selective Sensing of Formaldehyde at a Low Working Temperature.

Formaldehyde (HCHO) is a prevalent indoor gas pollutant that has been seriously endangering human health. Developing semiconductor metal oxide (SMO) gas sensors for selective measurement of formaldehyde at low working temperatures remains a great challenge. In this work, silver/tin-polyphenol hybrid spheres are applied as a sacrificial template for the fabrication of spherical mesoporous Ag2O/SnO2 sensing materials. The obtained mesoporous Ag2O/SnO2 spheres have a uniform particle size (∼80 nm), large pore size (5.8 nm), and high specific surface area (71.3 m2 g-1). The response is 140 toward formaldehyde (10 ppm) at a low working temperature (75 °C). The detection limit reaches a low level of 23.6 ppb. Most importantly, it has excellent selectivity toward interfering gases. When the concentration of the interfering gas (e.g., ethanol) is 5 times as high as that of formaldehyde, the response is little affected. Theoretical calculations suggest that the addition of Ag2O can significantly enhance the adsorption energy toward formaldehyde, thus improving formaldehyde sensing performance. This work demonstrates an efficient self-template synthesis strategy for noble metal catalyst-decorated mesoporous metal oxide spheres, which could boost gas sensing performance at a lower working temperature.

Self-templated synthesis of core-shell Fe3O4@ZnO@ZIF-8 as an efficient visible-light-driven photocatalyst

Compared to UV-driven catalysts, the utilization of sunlight to design efficient visible light catalysts remains much less explored. Herein, we prepared Fe3O4@ZnO@ZIF-8 three-component core-shell nanoparticles and investigate their corresponding photocatalytic degradation by using Rhodamine B (RhB) as a model contaminant under visible light. It is found that Fe3O4@ZnO@ZIF-8 demonstrates a significant enhancement in the photocatalytic degradation efficiency (98% of RhB was degraded within 100 min) with a reaction rate constant of 0.0292 min−1. These findings mark the significance of precise tailoring of core-shell Fe3O4@ZnO@ZIF-8 for achieving the desired degradation efficiency of organic pollutants under visible light.