Self-sacrificing Template Research Articles

Al-Based MOF-Derived Amorphous/Crystalline Heterophase Cobalt Sulfides as High-Performance Supercapacitor Materials.

Transition metal sulfides (TMSs) are promising electrode materials due to their high theoretical specific capacitance, but sluggish charge transfer kinetics and an insufficient number of active sites hamper their applications in supercapacitors. In this work, a self-sacrificial template strategy was employed to construct Al-based MOF-derived metal sulfides with an amorphous/crystalline (a/c) heterophase, in which aluminum, nitrogen, and carbon species were evenly coordinated in the amorphous phase. The metal sulfides a/c-Co(Al)S-1 and a/c-Co(Al)S-2, originating from the CAU-1 and CoAl-MOF on NF as self-sacrificial templates, were investigated as electrode materials, respectively, in which the a/c-Co(Al)S-1 showed a more excellent electrochemical performance. Through acid etching CAU-1 using Co(NO3)2 followed by sulfuration, the a/c-Co(Al)S-1 with a unique 3D network structure was constructed, whose unique architecture expanded the interfacial contact with the electrolyte and provided vast active sites, accelerating the charge transportation and ion diffusion. Notably, the a/c-Co(Al)S-1 displayed a high specific charge of 1791.8 C g-1 at 1 A g-1, satisfactory cycle stability, and good rate capability. The corresponding assembled a/c-Co(Al)S-1//AC device delivered a high energy density of 77.1 Wh kg-1 at 800 W kg-1 and good durability (87.4% capacitance retention over 10 000 cycles).

Scalable Production of 2D Non-Layered Metal Oxides through Metal-Organic Gel Rapid Redox Transformation.

Two-dimensional (2D) nonlayered metal compounds with porous structure show broad application prospects in electrochemistry-related fields due to their abundant active sites, open ions/electrons diffusion channels, and faradaic reactions. However, scalable and universal synthesis of 2D porous compounds still remains challenging. Here, inspired by blowing gum, a metal-organic gel (MOG) rapid redox transformation (MRRT) strategy is proposed for the mass production of a wide variety of 2D porous metal oxides. Adequate crosslinking degree of MOG precursor and its rapid redox with NO3 - are critical for generating gas pressure from interior to exterior, thus blowing the MOG into 2D carbon nanosheets, which further act as self-sacrifice template for formation of oxides with porous and ultrathin structure. The versatility of this strategy is demonstrated by the fabrication of 39 metal oxides, including 10 transition metal oxides, one II-main group oxide, two III-main group oxides, 22 perovskite oxides, four high-entropy oxides. As an illustrative verification, the 2D transition metal oxides exhibit excellent capacitive deionization (CDI) performance. Moreover, the assembled CDI cell could act as desalting battery to supply electrical energy during electrode regeneration. This MRRT strategy offers opportunities for achieving universal synthesis of 2D porous oxides with nonlayered structures and studying their electrochemistry-related applications.

ZIF-8 loaded Ag/ZnO electrospun nanofibers enabling high-performance H2 gas sensing for battery safety early warning

Safety issues triggered by battery thermal runaway have become the most crucial obstacle to the future development of the high-energy-density energy storage systems. As hydrogen (H2) will be inevitably generated along with heat release caused by the side reactions in the early stages of battery thermal runaway, rapid monitoring of trace H2 is considered as an effective measure enabling the battery safety early warning. Herein, to develop high-performance H2 sensing materials to monitor of low-concentration H2 leakage, ZIF-8 loaded Ag/ZnO electrospun nanofibers (ZAZ NFs) were designed by electrospinning and self-sacrificial template methods. Benefiting from all the enrichment and sieving effects of ZIF-8 shell, the catalytic and sensitization effects of Ag and abundant active sites provided by Ag and ZIF-8 loading, the ZAZ sensor enables ppb-level limit of detection toward H2, fast response (9 s), high selectivity and excellent humidity resistance. Furthermore, this ZAZ sensor can also realize the safety early warning (67.79 s before battery bulge) for practical pouch lithium cells, highlighting its great application potential in future advanced battery safety management system.

Controllable synthesis of 3D PdCu/Ti3C2Tx hierarchical nanostructures for chemiresistive room temperature H2 sensors

To enhance the detection performance of hydrogen (H2), we employed a self-sacrificing template method to prepare a three-dimensional (3D) PdCu-modified Ti3C2Tx nanocomposite, denoted as PdCu/Ti3C2Tx. Within 3D PdCu/Ti3C2Tx nanocomposite, PdCu as the active center component, was evenly distributed on Ti3C2Tx nanosheets. The unique architecture increased the exposure of active center sites, while the Ti3C2Tx nanosheets provided additional gas diffusion channels, thereby contributing to improved gas sensing performance. Comparing to PdCu nanoparticles, PdCu/Ti3C2Tx exhibited an enhancing response and a fast response time of 4 s to 0.5 % H2. PdCu/Ti3C2Tx also showed an ultra-low detection limit of 0.1 % H2 and excellent repeatability, selectivity and long-term stability. The outstanding gas sensing performance could be attributed to the 3D structure and the heterostructure between PdCu and Ti3C2Tx. The insights gained from this study provide novel perspectives for designing and synthesizing high-performance gas-sensitive materials.

Co-doped hollow nanospheres with low Pt loading for electrocatalytic oxygen reduction and zinc-air batteries

Preparing high-performance catalysts for oxygen reduction reaction (ORR) with low Pt loading is crucial to promote the development of clean energy storage devices such as metal air batteries. Herein, Co/N-HCMs support material with isolated Co atoms and hollow flower-like structure could be prepared by a self-sacrificing template strategy. Co/N-HCMs are then used to anchor Pt to obtain PtCo/N-HCMs catalyst with low Pt loading. Thanks to its improved specific surface area, hierarchical porous structure, and reinforced metal-support interactions, the obtained PtCo/N-HCMs deliver high onset potential of 0.99 V and half-wave potential of 0.82 V, and an excellent durability. When used as air cathode catalyst, PtCo/N-HCMs-based Zinc-air battery (ZAB) exhibits a power density of up to 202 mW cm−2, which is significantly better than ZAB assembled with commercial Pt/C. This study provides an effective strategy for preparing high-performance electrocatalysts with low precious metal content for use as the cathode of metal-air batteries.

Engineering Internal and External Low-Coordination Atoms in Nickel-Organic Framework Nanoarrays to Promote the Electrochemical Oxygen Evolution Reaction.

Monometallic nickel-organic frameworks based on a carboxylated ligand [2,6-naphthalenedicarboxylic acid (Ni-NDC)] have abundant and uniformly distributed single-atom Ni sites, enabling superior oxygen evolution reaction (OER) activity. In theory, most of the Ni atoms inside Ni-NDC microcrystals are coordinatively saturated except for the surface. Therefore, there are no accessible low-coordination atoms (LCAs) as electrocatalytic sites for the OER. One effective way is to expose more LCAs by preparing self-supporting Ni-NDC nanoarrays (Ni-NDC NAs) with hierarchical secondary structural units. Another effective method is to create more internal LCAs by removing partial ligands or coordination atoms attached to the Ni atoms. Herein, by combining the two strategies, we engineered LCAs in the interior and exterior of Ni-NDC to synergistically accelerate the OER. In brief, ultrathick "brick-like" Ni-NDC NAs were first prepared with dissolution and coordination effects of NDC on self-sacrificial templates of "agaric-like" nickel hydroxide nanoarrays [Ni(OH)2 NAs]. Subsequently, dual-coordinated NDC was partially replaced by monocoordinated 2-naphthoic acid (NA). The Ni-NDC NAs were further tailed into ultrathin "liner leaf-like" nanoneedle arrays (LCAs-Ni-NDC NAs). As a consequence, the LCAs-Ni-NDC NAs have more internal and external LCAs, which can deliver an OER performance that is superior to that of Ni-NDC NAs.

Metal-Organic-Framework Derived Co-Mo Multimetal Oxide Semiconductors: Selective Trace-Level Hydrogen Sulfide Detection.

The development of a highly selective and trace-level gas sensing platform for detecting hydrogen sulfide (H2S) remains a formidable challenge. To solve this problem, Co-Mo multimetal oxide semiconductors are rationally tailored by employing metal organic frameworks (MOFs) as self-sacrificial templates. The MOF-derived Co3O4/β-CoMoO4 based gas sensors displays high sensitivity (Rg/Ra = 22) to 10 ppm of H2S and ultralow limit of detection (10 ppb H2S). The formation of p-p heterojunction and multivalence states of Mo play a crucial role in electron transfer and oxygen adsorption. A sensor array constructed from four Co3O4/β-CoMoO4 materials with different Co/Mo ratios demonstrates a superior selective discrimination of H2S from other VOCs and malodorous gases by principal component analysis (PCA). Besides, a H2S gas sensing and alarming platform was designed for monitoring the environment contaminated with H2S. This finding provides a feasible approach for the discovery of highly efficient gas sensors to monitor environmental H2S concentration.

Self-sacrificing template synthesis of ultralight porous hydroxyapatite microtube-based ceramics for hemoglobin adsorption

Strong and porous hydroxyapatite ceramics are highly desired for biomedical materials. However, 1D hydroxyapatite crystals with enhanced bioactivity, densification, and sinterability are limited in practical application for self-agglomeration and unfavorable 3D morphology. Herein, a sacrificed template approach is developed to prepare ultralight porous hydroxyapatite microtube-based ceramics (HMTC). First, hydroxyapatite microtubes (HMTs) are self-assembled proceeding from nanowires to microtubes through a solvothermal reaction. Then, HMTs are shaped into 3D columns by using chitosan aerogel as a template and sintered at 1300 °C to obtain ultralight porous ceramics. The chitosan template considerably contributes to constructing the macro-meso-microporous architecture of HMTC, thereby benefiting the loading capacity, biomolecule migration, cell proliferation, and other biomedical applications. HMTC exhibits ultralight weight but excellent compressive resistance to bear objects weighing hundreds of times more. HMTC exhibits a high adsorption capacity (311 mg g−1) towards bovine hemoglobin (BHb) at the pH near pI by the driving force of ionic interaction and hydrophobic interaction. The adsorption kinetics and fixed-bed adsorption confirm that the physisorption process is controlled by the intraparticle diffusion of BHb. The excellent protein adsorption performance and good recyclability demonstrate the biological availability of HMTC.

Ultra-thin FeCoNi-LDH hollow nanoflower as solid-phase microextraction coating for targeted capture of six pesticides by electrostatic adsorption

Pesticides are common pollutants that cause detriment to the ecological environmental safety and health of human due to their toxicity, volatility and bioaccumulation. In this work, an ultra-thin polymetallic layered double hydroxide (FeCoNi-LDH) with hollow nanoflower structure composite was synthesized using ZIF-67 as a self-sacrificial template, which was used as solid-phase microextraction (SPME) coating for the targeted capture pesticides, which could be combined with high-performance liquid chromatography (HPLC) to sensitive inspection pesticides in real water samples. Orthogonal experimental design (OAD) was applied to ensure the best SPME condition. Additionally, the adsorption properties were evaluated by chemical thermodynamics and kinetics. Under the optimized conditions, high adsorption capacity was obtained (117.0–21.5 mg g−1). A wide linear range (0.020–1000.0 μg L−1), low detection limit (0.008–0.172 μg L−1) and excellent reproducibility were obtained under the established method. This research provided a new strategy for designing hollow materials with multiple cations for the adsorption of anion or organic pollutants.

WOx boosted hollow Ni nanoreactors for the hydrodeoxygenation of lignin derivatives

Reasonable design of non-noble metal catalysts with hollow open structure for hydrodeoxygenation (HDO) of lignin derivatives to value-added chemicals is of great significance but challenging. Herein, a novel MOF-derived multilayer hollow sphere coated nickel‑tungsten bimetallic catalyst (Ni2-WOx@CN-700) was fabricated via by confined pyrolysis strategy using bimetallic MOFs as a self-sacrificial template, which exhibits robust activity for the typical model HDO of vanillin to 2-methoxy-4-methylphenol (Yield of 100 % at 140 °C for no less than 10 cycles). The characterizations revealed that WOx facilitated the dispersion of Ni nanoparticles and adjusted the acidic capacity of the catalyst through the formed Ni-WOx heterojunction. Density functional theory (DFT) calculations confirms that WOx species enhanced the electron-rich nature of the active sites, while the adsorption energies of H2 and vanillin on Ni-WOx decreased from −0.572 eV and − 0.622 eV on Ni to −3.969 eV and − 4.922 eV, respectively. These results further indicated that the high activity of Ni2-WOx@CN-700 was attributed to the Ni-WOx heterojunction. Based on the characterizations and the thermodynamic calculations, the reaction mechanism was proposed. In addition, the catalyst shows good substrate universality, which enables its good commercial application prospect.

Self-sacrificed construction of versatile nanoadjuvant for synergistically enhanced immunogenic cell death and improved anti-tumor immunity

Immune checkpoint blocking (ICB) antibodies have witnessed great success in the clinic, but a significant subset of patients suffers from limited responses to ICB therapies. Collaboration of ICB therapy with immunogenic cell death (ICD) are expected to potentiate systemic antitumor immune response for tumor inhibition and metastasis prevention. In this study, we develop a novel Cu-Mn bimetallic nanoadjuvant (CMI-PEG) consist of porous CuMnOx with IR820 cargo and surface PEGylation for immune therapy. Under NIR laser irradiation, this CMI-PEG nanoadjuvant can induce PTT/PDT/CDT synergistic therapy with improved oxygen generation and GSH consumption, eliciting efficient ICD of tumor cells. Synergized with ICB antibodies, promoted T lymphocytes infiltration and increased antitumor immune responses are evoked for efficient inhibition of distant and metastasis tumor growth, which is emphasized by admirable in vivo experimental results. Collectively, this study presents a novel self-sacrificing template strategy to synthesize hollow and porous CuMnOx nanomateial and the constructed CMI-PEG nanoadjuvant holds great promise in synergistic ICD activation and potentiation of ICB therapy.

Boosting catalytic combustion of diesel soot particles over potassium-promoted CoMn-Co3O4 dual spinel structure catalyst

Catalytic oxidation is an effective method to remove soot particles from diesel exhaust, and the key aspect of this technology is to develop highly effective catalysts. In this work, a potassium-promoted dual spinel structure was prepared for soot elimination with the self-sacrificing template strategy. The highest activity was presented by the CoMn-0.2 H-10%K catalyst under a loose contact mode, with the temperature of soot conversion reaching 90% and turnover frequency value of 365 °C and 3.76×10−3 s−1, respectively. The catalyst was found to have a high content of oxygen vacancy and a superior ability for lattice oxygen migration, which led to elevated performance for soot combustion. The formation of K-OMS-2 at the interface between the CoMn spinel and the Co3O4 spinel was one of the reasons for the elevated lattice oxygen migration at low temperatures. This work provides an effective way to prepare transition metal catalysts for soot combustion.

Ruthenium nanoparticles supported on functionalized carbon nanotubes as high-efficiency catalysts for ammonia borane hydrolysis

Developing high-activity catalysts for the hydrolysis of ammonia borane (NH3BH3; AB) is a crucial and urgent task, which is presently considered an effective strategy for hydrogen generation in the applications of portable proton exchange membrane fuel cells (PEMFCs). In this study, carbon nanotubes (CNTs) were modified by self-growth of metal-organic frameworks (MOFs) on their surfaces. As self-sacrificial templates, the carbonization of cobalt and nitrogen containing MOFs led to the modification of CNT. Subsequently, cobalt was transformed into cobalt phosphide (Co2P) via phosphatization to form Co2P/N co-decorated CNTs (NCP-CNTs). Ru/NCP-CNT catalysts were obtained by loading ruthenium nanoparticles (NPs) using a chemical reduction method and their catalytic performance for H2 production via the hydrolysis of AB was systematically investigated. Ru/NCP-CNTs exhibited excellent catalytic activity, with an initial high turnover frequency (TOF) of 193.9 molH2·molRu−1·min−1 and a low activation energy of 32.4 kJ·mol−1. The incorporation of Ru NPs and their excellent synergistic effect with the NCP-CNT supports can explain the improved performance. This work provides an updated approach for fabricating low-cost and high-efficiency catalysts for the hydrolysis of AB.

FeSe2 nanoparticles decorated nitrogen-doped carbon nanocubes for superior lithium-ion batteries

FeSe2 shows superior advantages as anode of lithium-ion batteries (LIBs) with abundant resources, high theoretical specific capacity, and environmentally friendly. However, the FeSe2 anode still faces great challenges balancing specific capacity, capability, and stability. In this work, we employ a self-sacrifice template of Fe-PBA coated with polydopamine to prepare FeSe2@Void@NC cubic nanostructures by one-step pyrolysis and selenization. The experimental results well elucidate the unique hollow cubic architectures with high surface area and abundant pore structure induce rapid adsorption storage, thus improving electrochemical kinetics. Benefiting from the enhanced ion diffusion kinetics and high conductivity through N-doped carbon coating, the FeSe2@Void@NC electrode demonstrates a considerable capability with a high specific capacity of 493.93 mAh g−1 (3 A g−1), and a stable cyclability with a reversible capacity of 498.5 mAh g−1 (1 A g−1) after 750 cycles. The full cells with FeSe2@Void@NC anode and LiFePO4 cathode also exhibit remarkable rate capability and stable cyclability. Our research provides profound insights into the structure engineering of alternative transition metal sulfide anode for LIBs with excellent electrochemical performance.

C3N4-digested intercalation MoS2 nano-flowers with expanded interlayer spacing towards high-performance rechargeable zinc-ion batteries

Molybdenum disulfide (MoS2) materials are very competitive cathode materials for aqueous zinc-ion batteries (AZIBs) due to their sandwich structure, large surface area and low cost. Also, the inherent low capacity and high energy barrier limit its further development. Here, the C3N4-digested intercalation MoS2 (MSCN) has been achieved via a hydrothermal strategy by using g-C3N4 nanosheets as a self-sacrificial template. The introduction of g-C3N4 greatly improves the MoS2 conductivity, which further enhances the Zn2+ diffusion dynamics, and succeeds in increasing the spacing between the layers. With a discharge capacity of 168 mAh g−1 at 5 A g−1, Zn-ion batteries based on the MSCN cathode assembly exhibit good cycle stability and excellent rate performance, under the same current density circulation capacity remain a rate of 92.9 % after 1000 cycles. And beyond that, flexible quasi-solid ZIBs with MSCN cathodes which have good Zn2+ storage properties and promising for future applications. The research in this article is of great significance for the design and development of AZIBs layered transition metal sulfide cathodes.

Deciphering multistep transformation mechanism of cobalt-vanadium bimetallic sulfides anode in sodium storage

Transition metal sulfides as a high specific capacity sodium-ion batteries (SIBs) anode which have been suffering from successive phase transitions bringing about stress changes, poor electronic conductivity and ineffective ion transport kinetics. Combining self-sacrificial templates and ion-exchange transition reaction mechanisms, herein, cobalt, vanadium bimetallic sulfides hollow nano-cubic boxes with nitrogen-doped nanocarbon coating layer (CoV2S4@NC) are designed to solve these symbiosis problems. With a combination of in-situ Raman, ex-situ XPS/TEM, and density-functional theory calculations, the synergistically coordination mechanism between cobalt and vanadium binary metal during multi-step conversion processes is responsible for the faster charge transfer kinetics and boosted Na+ pseudocapacitance storage capability. Furthermore, the hollow cubic structure combined with the carbon shell layer can release the internal stress during phase transitions and avoid the recurrent growth of SEI film by volume change during the electrochemical process, thus realizing a superior electrode/electrolyte interface. Thus, when used as anode materials for SIBs, the prepared anode materials display excellent electrochemical performance, delivering capacity of 492 mA h g−1 at a current density of 10 A g−1 and high capacity stability with 484 mAh g−1 after 1000 cycles at 5 A g−1. More importantly, the assembled full cell (Na3V2(PO4)3//CoV2S4@NC) also shows high capacity of 574 mAh g−1 with 94.7% capacity retention after 85 cycles, suggesting the potential application of bimetallic sulfides in SIBs.

Fabrication of Cu-MOF-Derived Cu/CuxO/C Bifunctional Materials for Light and Dark Catalytic Properties.

Metal-organic frameworks (MOFs) are self-assembled constitutive precursors and efficient self-sacrificial templates with metal ions/clusters and organic linkers from which multifunctional materials with carbon nanostructures can be derived. In this study, we synthesized a novel Cu-MOF with Cu(II) as the central metal ion through two ligands, N,N'-bis(pyridin-3-yl)terephthalamide (3-bpta) and fumaric acid (H2FA), which was used as a template for derivatizing carbon-based nanostructured materials of Cu and CuxO through doping with different materials (melamine, urea, and TiO2) in a simple and efficient one-step pyrolysis. The Cu/CuxO-1 catalyst possesses both dark-catalyzed degradation activity and photocatalytic reduction activity during water purification due to the hole-transfer ability between Cu+ and Cu2+ and its inhibition of electron-hole complexation. In the absence of light, force, and cocatalyst, it can also effectively remove azo dyes in water and effectively reduce Cr(VI) under the action of visible light; therefore, Cu/CuxO-1 can be used as a new type of bifunctional material for the removal of pollutants in water, which has a broad prospect.

Electron transfer in MOF-derived cobalt-magnesium oxide–carbon microsphere composite catalytic ozonation of thiamphenicol

Cobalt-magnesium oxide–carbon microsphere composite (Co-MgO-CMS), Cobalt-carbon nanosheet composite (Co-CNS), and magnesium oxide–carbon nanorod composite (MgO-CNR) were synthesized by the MOFs self-sacrificing template method. And they were used as the catalysts for catalytic ozonation of thiamphenicol (20 mg/L) in water at an initial pH of 7.0. The phase of Co-MgO-CMS is mainly composed of metallic cobalt, magnesium oxide and carbon according to X-ray diffraction and transmission electron microscopy analyses. Thiamphenicol removal efficiency is enhanced through Co-MgO-CMS catalytic ozonation (75.4 %, in 6 min), compared with those in ozonation alone (39.8 %), Co-CNS catalytic ozonation (43.2 %), MgO-CNR catalytic ozonation (65.1 %) and Mg-Co binary oxide (Mg2CoOy) catalytic ozonation (69.0 %). Self-increasing of solution pH, protonated hydroxyl groups and electron transfer on metallic Co and lattice Co2+ are advantageous for the ozone decomposition into reactive oxygen species in Co-MgO-CMS catalytic ozonation. Owing to the metallic Co in Co-MgO-CMS, the electron transfer ability of Co-MgO-CMS is better than that of Mg2CoOy according to the in situ electrochemical test. Moreover, electron transfers directly from metallic Co to ozone. While protonated hydroxyl groups are the key for electron transfer on lattice Co2+. A possible degradation pathway for thiamphenicol in Co-MgO-CMS catalytic ozonation is proposed according to the detected intermediates. This work provides insight into improvement on electron transfer ability of concerted acid-base catalyst in heterogeneous catalytic ozonation.

Non-magnetic hollow ZnO/C fabricated by a novel ZnO self-sacrificial template hollow engineering for efficient microwave absorption

Non-magnetic hollow ZnO/C fabricated by a novel ZnO self-sacrificial template hollow engineering for efficient microwave absorption

Highly selective methane sensing based on enhanced dual sieving effects by ZnO/Pd@Co node-replaced ZIF-8 nanorods

Highly selective methane sensing remains a formidable challenge in the field of metal oxide semiconductor (MOS)-based gas sensors. To address this issue, zeolitic imidazolate framework (ZIF) modulation is considered as an effective approach because of its pore size sieving and polarity sieving effects. In this work, core-shell ZnO/Pd@Co node-replaced ZIF-8 (ZIF-8/67) nanorods were synthesized by self-sacrificial template method, followed by post-synthetic modification of ZIF-8. When the replacement ratio of Co nodes reached 12.4%, ZnO/Pd@ZIF-8/67 exhibited a response of 12.2% to 500 ppm CH4 at 210°C but no response to 50 ppm CO, 50 ppm NH3 and 5 ppm NO2, showing excellent selectivity. By limiting rotational freedom of 2-methylimidazole, Co node replacement decreased the effective pore size from 4.0 to 4.2 Å to 3.8–4.0 Å and hindered the diffusion of NO2 with the dynamic diameter of 4.5 Å, thus enhancing the pore size sieving effect. Moreover, polarity sieving effect is also enhanced due to the favourable adsorption of polar CO (3.76 Å) and NH3 (2.6 Å) by ZIF. Therefore, the selectivity of nonpolar CH4 (3.8 Å) was improved. This work provides a new strategy for reasonably controlling and modulating the ZIF structure to achieve high selectivity in MOS-based sensors.