A Nb2C MXene-derived ternary photocatalyst composite (In2S3/Nb2O5/Nb2C) was successfully synthesized through a one-pot in-situ hydrothermal method. The optimized composite shows excellent ...photocatalytic activity for H2 evolution due to the synergic effect of In2S3/Nb2O5 heterojunction over Nb2C MXene substrate. According to the spectroscopy and electrochemical analysis, the composite has a dramatically narrowed bandgap, which helps to absorb a larger wavelength of light and accelerates the separation of photoexcited charge carriers. Furthermore, a predominate S-scheme heterojunction charge transfer along with Schottky junction were confirmed between In2S3 and NCC, which contribute to increasing the photocatalytic activity for H2 production.
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MXene-derived photocatalysts continue to fascinate the research community in developing photo-driven green and sustainable fuel production. However, the efficiency of MXene-derived photocatalyst is still low due to the wide bandgap and high recombination rate of photo-excited charge carriers. Here, we have synthesized the Nb2C MXene-derived ternary photocatalyst via one-pot in-situ hydrothermal method for photocatalytic hydrogen (H2) evolution. The partial oxidation of Nb2C MXene into Nb2O5 nanorods and coupling with In2S3 nanoparticles via in-situ chemical anchoring were the key factors toward high efficiency and long-term stability during photocatalytic H2 evolution. The optimized ternary photocatalyst composite manifested the highest H2 evolution efficiency at 68.8 µmol g−1 h−1, which was 11 and 7.5 times higher than the Nb2O5/Nb2C (NNC) and pure In2S3 photocatalyst, respectively. Moreover, the photocatalytic stability of the optimized ternary photocatalyst composite was analyzed for five consecutive cycles, and above 87% activity retention was observed even after the fifth cycle without any obvious decline. The separation efficiency of photoexcited charge carriers could be attributed to the synergic effect of the In2S3/Nb2O5 heterojunction and the redox reactions at different sites of the composite. More importantly, the participation of Schottky junction and S-scheme heterojunction charge transfer for the obtained novel ternary photocatalyst was evaluated via ultraviolet photoelectron spectroscopy (UPS) and electron paramagnetic resonance (EPR). This research will provide additional insight into the extended potential of MXene-derived ternary photocatalysts towards efficient H2 production to meet future global energy demands.
Laser powder bed fusion (LPBF) additive manufacturing provides the freedom to manufacture the novel bionic structures and materials with excellent mechanical properties (e.g., combining high strength ...and toughness). In this work, inspired by the laminar structure of natural shells, the TiN/Ti6Al4V sandwich structural materials were fabricated in the atmosphere with different ratios of nitrogen and argon. The elemental diffusion, in-situ synthesis between N and Ti atoms, microstructure evolution, and mechanical properties of LPBF-processed TiN/Ti6Al4V sandwich composites were investigated. TiN induced by the in-situ synthesis between N and Ti atoms was observed, which exhibited an excellent metallurgical bond with the Ti6Al4V matrix. The microhardness of the TiN/Ti6Al4V layer varied from 409.62 HV0.2 and 442.55 HV0.2 with different nitrogen concentrations. The tensile strength and ductility of LPBF-processed TiN/Ti6Al4V sandwich composite parts were enhanced by the combination of bio-inspired lamellar structure and internal ceramic particle reinforcement. Interlayer hard-soft phase combination in the composite parts could be contributed to the excellent mechanical properties with an ultimate strength of 1303.12 MPa and a plastic strain of 8.9%. This study demonstrates that a flexible combination of the LPBF process and reactive atmosphere can in-situ additive manufacture the novel periodic lamellar ceramic/metal heterogeneous materials with excellent mechanical performance (e.g., rigid, wear-resistant, corrosion-resistant and toughness).
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•Nitrogen solution and grain refined strengthening to enhanced mechanical properties of LPBF Ti6Al4V alloy.•TiN/Ti6Al4V sandwich structure composites were in-situ prepared by LPBF under different nitrogen concentrations.•Ti-MSSCs exhibit significantly high strength of ∼1330 MPa and ductility of ∼9%.•Interface pinning effect of in-situ synthesized TiN ceramic particles occurred in Ti-MSSCs.
In this study, a hierarchical Bi2O3/TiO2 fibrous composite was in-situ fabricated on an electrospun TiO2 nanofiber at ambient temperature. In the Bi2O3/TiO2 composite, S-scheme electron migration ...occurred between Bi2O3 and TiO2. In the photocatalytic degradation of phenol under simulated sunlight, the as-prepared Bi2O3/TiO2 nanofibers considerably outperformed Bi2O3 nanoparticles and TiO2 nanofibers. This improvement is contributed by maintaining and effectively utilizing the useful carriers and consuming the useless holes and electrons, realized by the S-scheme heterojunction and hierarchical structure. This study also provides an alternative design fashion for photocatalysts.
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•FeNiOOH nanosheets are grown via in-situ chemical oxidation of 3D FeNi foam (FNF).•Oxyhydroxide species can directly act as real active catalyst for water oxidation.•The FeNiOOH/FNF ...exhibits superior OER performance to commercial IrO2 catalyst.•The superb catalytic performance owes to rational composition and structure design.
The design and synthesis of efficient and affordable electrocatalysts for water oxidation are essential to advance water splitting technology, which depends on developing earth-abundant catalytic materials with rational compositions and structures. Here, we propose a facile synthesis of FeNiOOH nanosheets grown on FeNi foam (FNF) by in-situ chemical oxidation as a novel 3D electrode for oxygen evolution reaction (OER). This FeNiOOH/FNF electrode shows outstanding electrocatalytic performance in alkaline electrolyte, including high OER activity that requires a small overpotential of 252 mV to achieve a current density of 10 mA cm−2, favourable OER kinetics with a low Tafel slope of 36.8 mV dec−1, and excellent operation stability for at least 50 h. The superior OER properties are resulted from the highly active FeNi-oxyhydroxide species and advantageous nanosheet array structure. This work presents an effective strategy to rationalize self-supporting electrodes consisting of nanostructured arrays on conductive substrates, creating new opportunities to search for more advanced materials towards a sustainable energy future.
The synthesis and processing of most polymer adhesives rely on energy-inefficient and environmentally burdensome manufacturing approaches. In this paper, a novel synthesis strategy, UV-initiated ...frontal polymerization (FP) for the fast synthesis of high-strength, self-propagating epoxy adhesives at room temperature, was presented, in which the self-propagating rate reached 71.4 mm min−1. CuCl2 was used as a catalyst to decrease the onset temperature of polymerization and ensure sufficient polymerization on the surface of the material to be bonded. Mild steel, glass, ceramic, wood, PMAA, and concrete were successfully bonded within several minutes at room temperature. In the same material system, the adhesive strength with the FP curing approach was greater than that of thermal curing, and the former had a better pore structure, as determined by MIP analysis. This paper provides a promising idea for the in-situ fast synthesis of high-strength epoxy adhesives at room temperature.
A novel synthesis strategy, UV-initiated frontal polymerization (FP) for the fast synthesis of high-strength, self-propagating epoxy adhesives at room temperature, was presented, in which the self-propagating rate reached 71.4 mm min−1. CuCl2 was used as a catalyst to decrease the onset temperature of polymerization and ensure sufficient polymerization on the surface of the material to be bonded. Moreover, the thermal images clearly recorded the synthesis process and temperature distribution during the RICFP. Display omitted
•A novel synthesis strategy, radical induced cationic frontal polymerization for the fast synthesis of high-strength, self-propagating epoxy adhesives, was presented at room temperature.•The adhesion of various materials was successfully achieved.•The self-propagating reached 71.4 mm min−1.
The exploration of high-efficiency, long-durability, and cost-effectiveness transition metal doped carbon materials to replace the commercial Pt/C in oxygen reduction reaction (ORR) is greatly ...desirable for promoting the advancement of sustainable energy devices. Herein, the Fe3N and FeCo alloy decorated N-doped carbon hybrid material (denoted Fe3N-FeCo@NC) is prepared and applied as the ORR catalyst, which is derived from the two-step pyrolysis of an intriguing complex consisted of metal-coordinated porous polydopamine (PDA) nanospheres (i.e., Fe-PDA@Co) and melamine. The resulting Fe3N-FeCo@NC delivers outstanding ORR activity with an onset potential (Eon) of 1.05 V, a half-wave potential (E1/2) of 0.89 V, as well as excellent long-term stability and methanol resistance over Pt/C. Interestingly, the home-made Zn-air battery with Fe3N-FeCo@NC as the air-cathode demonstrates much higher open-circuit voltage (1.50 vs. 1.48 V), power density (141 vs. 113 mW·cm−2) and specific capacity (806.6 vs. 660.6 mAh·gZn−1) than those of Pt/C counterpart. Such a remarkable ORR activity of Fe3N-FeCo@NC may stem from the synergistic effect of Fe3N and FeCo active species, the large surface area, the hierarchical porous structure and the exceptional sphere/sheet hybridized architecture.
Metal–organic frameworks (MOFs) with high porosity and a regular porous structure have emerged as a promising electrode material for supercapacitors, but their poor electrical conductivity limits ...their utilization efficiency and capacitive performance. To increase the overall electrical conductivity as well as the efficiency of MOF particles, three-dimensional networked MOFs are developed via using preprepared conductive polypyrrole (PPy) tubes as the support for in situ growth of MOF particles. As a result, the highly conductive PPy tubes that run through the MOF particles not only increase the electron transfer between MOF particles and maintain the high effective porosity of the MOFs but also endow the MOFs with flexibility. Promoted by such elaborately designed MOF–PPy networks, the specific capacitance of MOF particles has been increased from 99.2 F g–1 for pristine zeolitic imidazolate framework (ZIF)-67 to 597.6 F g–1 for ZIF–PPy networks, indicating the importance of the design of the ZIF–PPy continuous microstructure. Furthermore, a flexible supercapacitor device based on ZIF–PPy networks shows an outstanding areal capacitance of 225.8 mF cm–2, which is far above other MOFs-based supercapacitors reported up to date, confirming the significance of in situ synthetic chemistry as well as the importance of hybrid materials on the nanoscale.
This work presents for the first time one-step ultrafast (precursor-free) synthesis of 1D MnFe2O4 (MFO) nanorods and soft magnetic colloidal nanoparticles (NPs) using microwave-assisted hydrothermal ...(MAH) methods, with or without citric acid (CA) as a surfactant (in situ synthesis), respectively. The mechanism of growth of spinel MFO nanostructures during the MAH synthesis was studied by varying synthesis duration (3–6 h) and temperature (180–200 °C). An increase in both the duration and temperature improved the purity of the samples, up to 97%. On the other hand, a temperature increase by 20 °C notably shortened the formation time of MFO nanorods, which have an average diameter and length of less than 20 nm and 350 nm, respectively, as observed at 200 °C after 6 h. All the fabricated MFO NPs with spherical and rod-like morphologies manifested high saturation magnetization in the range of 54–64 emu/g. The chelation of lattice metal ions by CA resulted in the formation of a stable colloid comprising 100% pure spinel MFO NPs with a size of ≤32 ± 10 nm (mean ± SD) and featuring very soft magnetic properties. This colloid was generated by the MAH synthesis at 175 °C within 30 min. Notably, an increase in synthesis duration from 30 min to 3 h diminished MFO phase purity from 100% to 52% and saturation magnetization from 43.4 ± 0.7 to 33.9 ± 2.0 emu/g for CA-functionalized MFO NPs owing to CA degradation increasing during the in situ MAH synthesis with longer duration. This study indicates good potential of ultrafast MAH synthesis for the development of 1D magnetic spinel nanostructures with controllable morphology, size, magnetic properties, and colloidal stability, thereby offering a wide range of applications within the fields of adsorption, catalysis, electronics, and biomedicine.
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•Preparation approaches, general properties, emerging applications and future challenges of MOF/CNM composites are reviewed.•In-situ preparation strategy leads to stronger interfacial ...bonding between MOFs and CNMs compared with ex-situ preparation strategy.•MOF/CNM composites in forms of hydrogel, powder, membrane and aerogel can be prepared through different post-treatments.•MOF/CNM composites exhibit high specific surface area, hierarchically porous structure, and superior mechanical and electrochemical properties.•MOF/CNM composites hold promise for applications in the fields of water remediation, air purification, electrochemical devices and biomedicines.
Metal organic frameworks (MOFs) have been widely used in various emerging fields due to their attractive characteristics, such as large specific surface area, highly porous structure, tunable porosity and pore size, versatile surface chemistry, diverse topological structure, and high chemical and thermal stability. However, nanoscale MOFs are prone to agglomeration, and their inherently crystalline structure leads to poor flexibility, processability and recyclability, which seriously limit the performance and application of MOFs. To address these deficiencies, MOFs have been composited with other materials through different strategies. One such attractive material is cellulose nanomaterials (CNMs), the most abundant and sustainable biomass on the earth. Herein, recent advances in the MOF/CNM composites in terms of preparation approaches, general properties, and emerging applications are overviewed, aiming to provide some useful guidance to researchers on the rational design of high-performance MOF/CNM composites in different forms for advanced applications in the future. Particularly, MOFs and CNMs are usually compounded in aqueous solutions through two main strategies, i.e., in-situ synthesis and ex-situ blending. Further processing of as-prepared MOF/CNM aqueous mixtures can generate MOF/CNM composites in four forms, i.e., hydrogel, powder, membrane and aerogel. Benefitted from advantages of both MOFs and CNMs, MOF/CNM composites hold exceptional high specific surface area, hierarchically porous structure, as well as superior electrochemical, mechanical and antibacterial properties, which can be further modulated and enhanced through optimizing type and composition of MOFs and CNMs, preparation method, and addition of other functional components. These exceptional properties offer huge potential in a wide range of application fields.
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•A novel in-situ synthesis strategy for preparation of a 0.6 wt% Ir@ZrO2@C.•A highly selective and acid-resistant catalyst for the levulinic acid hydrogenation.•Single atom feature of ...Ir revealed by AC-HAADF-STEM, XPS, IR-CO and H2-TPR.•Ultra-stability in LA-to-GVL hydrogenation under harsh and acidic conditions.•The ultra-stability arises from the well-defined structure of the Ir@ZrO2@C.
The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is a key reaction for the production of renewable chemicals and fuels, wherein acid-resistant and robust catalysts are highly desired for practical usage. Herein, an ultra-stable 0.6 wt% Ir@ZrO2@C single-atom catalyst was prepared via an in-situ synthesis approach during the assembly of UiO-66, followed by confined pyrolysis. The Ir@ZrO2@C offered not only a quantitative LA conversion and an excellent GVL selectivity (>99%), but also an unprecedented stability during recycling runs under harsh conditions (at T = 453 K, PH2 = 40 bar in pH = 3 or pH = 1 aqueous solution). By thorough spectroscopy characterizations, a well-defined structure of atomically dispersed Irδ+ atoms onto nano-tetragonal ZrO2 confined in the amorphous carbon was identified for the Ir@ZrO2@C. The strong metal-support interaction and the confinement of the amorphous carbon account for the ultra-stability of the Ir@ZrO2@C.
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