Self-sacrificial Template Method Research Articles

Facile synthesis of dual-MOF ultrathin nanosheets supported on layered double hydroxides heterostructure: Electron modulation strategy for enhanced electrocatalytic water splitting

In this study, we achieved electron environment modulation of MOF-based electrocatalyst by creating a dual-functional heterostructure using two-dimensional (2D) MOFs and layered double hydroxides (LDH), to enhance its electrocatalytic performance. Through a self-sacrificial template method, ultrathin hybrid dual-MOF (CoBDC and MIL-100(Fe)) nanosheets were grown on LDH, forming DM@CoFeRu-LDH, a 2D heterostructure benefiting from interference co-growth on the 2D scaffold. The thickness of dual-MOF nanosheets can be controlled by regulating the nucleation and reaction kinetics. Specifically, with a thickness ranging from 1–1.5 nm, it effectively exposes more active sites and accelerate electron and mass transfer. Additionally, electron transfer occurred between the dual-MOF and LDH heterostructures, leveraging synergistic effects from multi-metal centers to achieve an optimal electron structure. DM@CoFeRu-LDH exhibited the lowest energy barrier for the rate-determining step in the oxygen evolution reaction, along with a favorable hydrogen adsorption energy for the hydrogen evolution reaction. As a result, the DM@CoFeRu-LDH demonstrated efficient electrocatalytic activity, requiring only a voltage of 1.50 V to achieve a current density of 10 mA cm−2.

Oxalate-derived porous C-doped NiO with amorphous-crystalline heterophase for supercapacitors

Constructing amorphous/crystalline heterophase structure with high porosity is a promising strategy to effectively tailor the physicochemical properties of electrode materials and further improve the electrochemical performance of supercapacitors. Here, the porous C-doped NiO (C-NiO) with amorphous/crystalline heterophase grown on NF was prepared using NF as Ni source via a self-sacrificial template method. Calcining the self-sacrificial NiC2O4 template at a suitable temperature (400 °C) was beneficial to the formation of porous heterophase structure with abundant cavities and cracks, resulting in high electrical conductivity and rich ion/electron-transport channels. The density functional theory (DFT) calculations further verified that in-situ C-doping could modulate the electronic structure and enhance the OH− adsorption capability. The unique porous amorphous/crystalline heterophase structure greatly accelerated electrons/ions transfer and Faradaic reaction kinetic, which effectively improved the charge storage. The C-NiO calcined at 400 °C (C-NiO(400)) displayed a markedly enhanced specific charge, outstanding rate property and excellent cycling stability. Furthermore, the hybrid supercapacitor assembled by C-NiO(400) and active carbon achieved a high energy density of 49.0 Wh kg−1 at 800 W kg−1 and excellent cycle stability (90.9 % retention at 5 A/g after 10 000 cycles). This work provided a new strategy for designing amorphous/crystalline heterophase electrode materials in high-performance energy storage.

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.

Ni-Co hexacyanoferrate hollow nanoprism with CN vacancy for electrocatalytic benzyl alcohol oxidation.

An innovative method to improve the oxidation efficiency of benzyl alcohol utilizes Ni-Co hexacyanoferrate hollow nanoprisms. Synthesized via a gentle self-sacrificial template method, this catalyst exhibits substantial catalytic activity and selectivity towards benzyl alcohol oxidation, facilitated by the strategic incorporation of Co to modulate CN vacancy density. Impressively, it achieves a current density of 10 mA cm-2 at 1.33 V and a remarkable 98% efficiency in benzyl alcohol conversion at 1.4 V.

K+-Pre-Intercalated α-K0.2MnTi0.07O0.8 Hollow Nanotubes for High-Performance Na+ Supercapacitors

Transition metal oxides have attracted extensive research interest for supercapacitors due to efficient ion accessibility of nanostructures. Here, hierarchically hollow α-K0.2MnTi0.07O0.8 nanotubes with high K content are prepared via a self-sacrificial template method. The electrochemical performance of α-K0.2MnTi0.07O0.8 nanotubes is significantly improved when beneficial K+ is intercalated into a considerably ordered α-MnO2 phase with exchangeable Mn–K slabs by a K-pre-reserved reaction. Significantly, the α-K0.2MnTi0.07O0.8 nanotubes activated in a K2SO4 electrolyte exhibit highly capable capacitance behavior with high specific capacitance (334.5 F g–1 at 1 A g–1) and superior cycling stability (88% capacitance retention of the initial after 60,000 cycles). The well-designed α-K0.2MnTi0.07O0.8-based supercapacitor device exhibits an energy density of 25.16 Wh kg–1 at 1600 W kg–1. The morphological electrode-structured designer could be a promising attempt for applications in energy-related fields and even beyond power and storage sources.

External and internal dual-controls: Tunable cavity and Ru–O–Co bond bridge synergistically accelerate the RuCoCu-MOF/CF nanorods for urea-assisted energy-saving hydrogen production

Currently, there are still many limitations in the research of conductive metal-organic frameworks (MOFs) in the field of electrocatalysis. On the one hand, most MOFs have a solid construction, seriously hindering their mass transfer process. On the other hand, innate bonding is not conducive to the optimization of electronic structures and the excitation of intrinsic active sites. Therefore, external/internal dual-control of MOFs is urgently needed to break the shackles of their activity. Herein, the hollow RuCoCu-MOF/CF nanorods with tunable cavities are directionally constructed by a self-sacrificial template method. Benefiting from the exact morphological control and the unique Ru–O–Co bond bridge, RuCoCu-MOF/CF exhibits superior performances for alkaline hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). Surprisingly, a record-breaking voltage of 1.402 V drives a current density of 10 mA cm−2 for urea-assisted overall water splitting under alkaline conditions, greatly promoting the development of energy-efficient hydrogen production technology. This work firstly constructed the MOF-based self-supporting electrode with ultra-high urea-assisted hydrogen production and urea degradation performances via the dual controls of the cavity size and chemical bond bridge. This points out the direction for the development of unique integrated electrodes for both hydrogen production and decontamination.

Engineering a Co/Co2P Mott–Schottky heterostructure encased in a hollow N-doped carbon polyhedron as an advanced nanoreactor towards high-efficiency electrocatalytic oxygen evolution

Through a feasible self-sacrificial template method, a nanoreactor composed of Co/Co2P heterostructured nanoparticlesin situconfined in N-doped carbon hollow rhombic dodecahedrons (Co/Co2P@N-CHRDs) was designed as an excellent OER electrocatalyst.

Self-assembly of MAPbBr3/Pb-MOF heterostructures with enhanced photocatalytic CO2 reduction performance and stability

The MAPbBr3/Pb-MOF heterojunction in situ fabricated via a self-sacrificial template method demonstrated a photocatalytic CO2 reduction activity of 4.8 times larger than that of pristine MAPbBr3 and excellent photocatalytic stability.

Tuning the Electrical Conductivity of a Flexible Fabric-Based Cu-HHTP Film through a Novel Redox Interaction between the Guest-Host System.

Integration of metal-organic frameworks (MOFs) and flexible fabrics has been recently considered as a promising strategy applied in wearable electronic devices. We synthesized a flexible fabric-based Cu-HHTP film consisted of Cu2+ ions and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) via a self-sacrificial template method. The obtained Cu-HHTP film displays an outstanding nanostructured surface and uniformity. Iodine molecules are first introduced into the pores of Cu-HHTP to investigate the influence of guest molecules on electrical conductivity in a 2D guest-host system. After doping, the conductivity of the Cu-HHTP film shows an increased dependent on the doping time, and the maximum value is more than 30 times that of the original MOFs. The enhanced electrical conductivity results from an intriguing redox interaction occurred between the confined iodine molecules and the framework. The organic ligands are oxidized by iodine molecules, and generating new ions allows for subsequent participation in the regulation of the mixed valence bands of copper ions in MOFs, changing the ratio of Cu2+/Cu+, promoting the charge transport of the framework, and then synergistically enhancing the electronic conductivity. This study successfully prepared a flexible fabric-based conductive I2@Cu-HHTP film and presented insights into revealing the behavior of iodine molecules after entering the Cu-HHTP pores, expanding the possibilities of Cu-HHTP used in flexible wearable electronics.

Magnetic carbon nanoparticles derived from Co-based metal–organic frameworks for magnetic solid-phase extraction and determination of phenylurea herbicides

Magnetic carbon nanoparticles composed of Co, CoO and graphitic carbon (Co/CoO@C) were prepared by direct carbonization of Co-MOF without the need of extra carbon precursors and magnetic particles under N2 atmosphere. The Co/CoO@C prepared by self-sacrificial template method possess high mesoporous architecture, a large number of adsorption sites, good graphitization degree and strong magnetic response. The material was constructed as an adsorbent for magnetic solid-phase extraction of four phenylurea herbicides from water and rice samples prior to high-performance liquid chromatography analysis. A series of experimental parameters affecting the extraction efficiency were optimized. Under optimal conditions, the established method revealed extremely fast extraction times (10 s), low limits of detection (0.05 μg/L, S/N = 3), good linearity (0.1–100 μg/L) within the linear correlation coefficient range of 0.9990–0.9997 and good precision (RSD < 5.72 %). The results confirmed that the Co/CoO@C exhibited an excellent adsorption capability and could be a stable and effective adsorbent for preconcentrating trace levels of phenylurea herbicides from water and rice samples. Moreover, the excellent adsorption performance together with low-cost, facile synthesis method endowed the Co/CoO@C great application prospect in sample preparation.

Preparation of Cs/Cu-LDO@X catalysts and reaction mechanism of the side-chain alkylation of toluene to styrene

The Cu-LDH@X composite materials were synthesized using the in-situ self-sacrificial template method, and the acid-base bifunctional Cs/Cu-LDO@X catalysts were prepared by impregnation-calcination. The as-synthesized catalysts were characterized by XRD, N2 adsorption-desorption, SEM, HRTEM (EDS), FTIR, XPS, NH3-TPD, CO2-TPD techniques. The catalytic performance of the catalysts was evaluated in one step by implying a fixed-bed microreactor for the side-chain alkylation of toluene with methanol to styrene. The reaction mechanisms of the side-chain alkylation on the catalysts surface were deeply investigated. The Cs/Cu-LDO@X catalysts with adjustable acid-base sites and nanolayered structures demonstrated good catalytic performance for the side-chain alkylation of toluene. The Cs/Cu-LDO@X-3 catalyst exhibited the best catalytic performance with toluene conversion is up to 6.58%, while the selectivity of side-chain alkylated products and styrene is 91.64% and 54.16% respectively. The reaction mechanism investigation indicates that methanol dehydrogenated firstly to form formaldehyde under the action of the base sites on the catalyst surface, later, the adsorbed toluene on the acid sites underwent side-chain alkylation with formaldehyde. High selectivity of produced styrene owing to the synergistic interactions of acid-base sites and layered space-confined effects of the catalytic system.

Self-Sacrifice Template Construction of Uniform Yolk-Shell ZnS@C for Superior Alkali-Ion Storage.

Secondary batteries have been widespread in the daily life causing an ever‐growing demand for long‐cycle lifespan and high‐energy alkali‐ion batteries. As an essential constituent part, electrode materials with superior electrochemical properties play a vital role in the battery systems. Here, an outstanding electrode of yolk–shell ZnS@C nanorods is developed, introducing considerable void space via a self‐sacrificial template method. Such carbon encapsulated nanorods moderate integral electronic conductivity, thus ensuring rapid alkali‐ions/electrons transporting. Furthermore, the porous structure of these nanorods endows enough void space to mitigate volume stress caused by the insertion/extraction of alkali‐ions. Due to the unique structure, these yolk–shell ZnS@C nanorods achieve superior rate performance and cycling performance (740 mAh g−1 at 1.0 A g−1 after 540 cycles) for lithium‐ion batteries. As a potassium‐ion batteries anode, they achieve an ultra‐long lifespan delivering 211.1 mAh g−1 at 1.0 A g−1 after 5700 cycles. The kinetic analysis reveals that these ZnS@C nanorods with considerable pseudocapacitive contribution benefit the fast lithiation/delithiation. Detailed transmission electron microscopy (TEM) and X‐ray diffraction (XRD) analyses indicate that such yolk–shell ZnS@C anode is a typical reversible conversion reaction mechanism accomplished by alloying processes. This rational design strategy opens a window for the development of superior energy storage materials.

Bimetallic catalyst derived from copper cobalt carbonate hydroxides mediated ZIF-67 composite for efficient hydrogenation of 4-nitrophenol

4-nitrophenol (4-NP), a toxic pollutant, is ubiquitous in the environment and difficult to degrade in natural conditions. To deal with this contaminant, catalytic reduction of 4-NP is a promising way. Herein, we report a copper and cobalt nanoparticle decorated carbon framework (Cu/Co@CF) through a self-sacrificial template method derived from the copper cobalt carbonate hydroxides/zeolitic imidazolate framework-67 (CuCoCH/ZIF-67) composite. Served as a cobalt and copper source as well as a self-sacrificial template, CuCoCH extended the pore sizes of carbonized derivatives of ZIF-67 and synchronously transformed to bimetallic active sites. The catalyst exhibited a highly efficient catalytic performance and remarkable reusability for hydrogenation of 4-NP. The 4-NP conversion reached 99.7% in 1 min and the pseudo-first-order reaction kinetic constant was 5.122 min-1, which is the highest among similarly reported catalysts.

Template synthesis of molybdenum-doped NiFe-layered double hydroxide nanotube as high efficiency electrocatalyst for oxygen evolution reaction

Oxygen evolution reaction (OER) with four proton–electron coupled transfer process is a half-reaction that restricts the development of rechargeable metal-air batteries and water splitting devices, and it is of great significance to develop inexpensive and efficient OER catalysts. Herein, Mo-doped NiFe-layered double hydroxide (Mo–NiFe-LDH) nanotubes are synthesized using a self-sacrificial template method. Benefitting from the unique nanostructure, Mo–NiFe-LDH-2 exhibits a large electrochemical surface area of 63.94 cm2. In addition, a strong electronic interaction occurs between Mo, Fe, and Ni after Mo doping, resulting in highly active Ni3+ sites. Consequently, the Mo–NiFe-LDH-2 shows high OER activity with an overpotential of 317 mV to deliver a current density of 20 mA cm−2 and a small Tafel slope of 44 mV dec−1. This work provides a feasible strategy to develop high efficiency electrocatalysts through transition metal doping and structural regulation.

Structure modulation and properties of NiCo2O4 nanothorn electrode materials prepared by a self-sacrificial template method

Herein, we report the preparation of an effective and novel NiCo2O4 dendritic structure with nanothorn arrays, using a stepwise, bottom-up hydrothermal and self-sacrificial template method. Rod-like ZnO is synthesized on Ni foam as self-sacrificing template, and Ni-Co-based precursor is grown on it through a hydrothermal method. NiCo2O4 dendritic crystals are obtained by alkali etching of the template and calcination, which significantly enhance its performance on electrochemical energy storage. Although the ZnO matrix is removed by alkali etching, it provides a basis for the growth of Ni-Co oxide. Using ZnO as template is simple to operate and can directly determine the shape and size of the hollow structure. Meanwhile, the ZnO template core can be well separated from the hollow structure, and the template can be used without surface functionalization, which is more simple and efficient. The obtained material can be directly used as electrode material without further processing, offering the benefit of unique structural advantages and low electron transmission resistance, as there is no need to use a binder. The as-obtained NiCo2O4 nanothorn electrode exhibits excellent electrochemical performance. It shows ultrahigh specific capacitance of 1534 C g−1 at 1 A g−1 current density, good rate discharge performance (75.8% retention from 0.5 A g−1 to 5 A g−1), values superior to those of nanothorn NiO, Co3O4 and bare Ni-Co 1-2 nanosheet structures and excellent cycling ability (83% retention after 5000 cycles). The as-assembled Ni-Co 1-2//AC hybrid supercapacitor device also exhibits high energy density of 64.1 Wh kg−1 at the power density of 450 W kg−1.

Metal–Organic Framework-Derived CuS Nanocages for Selective CO 2 Electroreduction to Formate

Electroreduction of CO2 to target products with high activity and selectivity has techno-economic importance for renewable energy storage and CO2 utilization. Herein, we report a hierarchical CuS h...

Highly stable Ni-based catalysts derived from LDHs supported on zeolite for CO2 methanation

CO2 methanation can effectively reduce the concentration of CO2 in the air and decrease environmental pollution. Therefore, it is essential to synthesize catalysts with high carbon deposition resistance and stability. Herein, the highly stabilized Ni-based catalysts derived from hydrotalcites are prepared by the self-sacrificial template method and used for CO2 methanation. The prepared Ni-based catalysts maintain the morphology of the hydrotalcites precursors and the Ni particles are embedded in the AlOx substrate. The catalyst show high performance at 350 °C, 0.1 MPa and a high space velocity of 30,000 mL g−1 h−1, with the conversion rate of CO2 and selectivity of CH4 reaching 87.5% and 100%, respectively. More importantly, the activity of catalyst does not decrease after continuous reaction for 200 h at 350 °C with different space velocities (30,000 and 60,000 mL g−1 h−1) owing to the confinement of the AlOx substrate, which suppress the undesirable agglomeration and sintering of the Ni particles. This unique mosaic structure has certain reference significance for studying materials with excellent stability at high temperatures.

Atomically dispersed Ni species on N-doped carbon nanotubes for electroreduction of CO2 with nearly 100% CO selectivity

It is imperative to develop efficient and robust electrocatalysts for CO2 reduction reaction (CO2RR) that would overcome the sluggish kinetics and exhibit high current density. Porous carbon nanotubes with highly delocalized electrons and tubular structure are promising candidates for CO2RR due to it is favorable for the accessible of substrates to active sites. However, there are rare reports of using carbon nanotubes to stabilize single-atom active sites for CO2RR. Herein, a self-sacrificial template method is developed to disperse single atomic Ni sites on N-doped carbon nanotubes from metal-organic frameworks (MOFs) for highly efficient CO2RR. Compared with the corresponding other N-doped carbon stabilized Ni single-atom catalysts, the obtained hierarchically porous Ni/NCTs exhibited enhanced selectivity and activity for the electrochemical reduction of CO2 to CO with Faradaic efficiency of 98 %, turnover frequency (TOF) of 9366 h−1 and CO current density of 34.3 mA cm-2 at the applied potential of -1.0 V.

Self-Sacrificing Template Synthesis of Micro/Nano Spheres Ni6MnO8 as Electrode for High-Performance Lithium-Ion Batteries

Scalable preparation of micro/nano binary Ni-Mn oxides with good cyclability and low volume swing is crucial for their practical applications in lithium-ion batteries (LIBs). In this contribution, micro/nano quasi-spheres Ni6MnO8 (NMO) has been firstly prepared via a versatile precursor self-sacrificial template method. Compared to the reported approaches, the presented synthetic route is more facile, scalable and lower cost. When cycled against Li/Li+, notably, the resultant NMO micro/nano spheres indicate the safer operation potential and superior electrochemical performances over the commercial graphite anode. A long cyclability (506.9 mAh g−1 at 1C after 350 cycles) and an excellent rate capability (60 mAh g−1 at 5C) were achieved, which can be attributed to the structure feature of the micro/nano sphere and a so-called semi-reversible reaction, implying a perspective value for application in high energy-density LIBs.

Synthesis of hierarchical molybdenum disulfide microplates consisting of numerous crosslinked nanosheets for lithium-ion batteries

Hierarchical MoS2 microplates, consisting of numerous crosslinked nanosheets, are successfully synthesized using a self-sacrificial template method. MoO3 microplates (synthesized using a solution method) are used as the self-sacrificial template in the solvent thermal sulfidation process, resulting in the formation of MoS2 microplates. The resulting hierarchical structure possesses numerous active sites and a large surface area. As an anode material for LIBs, the hierarchical MoS2 microplates, both before and after the thermal treatment, demonstrate reversible and high capacity, and good rate capability. In addition, the energy storage performance of the MoS2 microplates is found to be significantly improved after thermal treatment. The annealed MoS2 microplates deliver a high specific capacity of 1220.8 mAh g−1 at a current density of 0.1 A g−1 and a high capacity retention of 84.8% (of the initial capacity) over 130 cycles. The high capacity and good rate capability suggest that the as-prepared hierarchical MoS2 microplates are a promising anode material for LIBs.