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Controlling the spatial confinement effect and highly dispersed Pd nanoparticles (NPs) can help to improve applicability in catalysis, energy conversion, and separation. However, the nonspatial confinement effect, agglomeration of Pd NPs of catalyst and harsh reaction conditions have become the urgent problems to be solved in Suzuki-Miyaura cross-coupling reaction. Herein, we report the first application of a new MOFs@COFs by using core with metal organic frameworks (MOFs) NH2-MIL-101(Fe) and shell with covalent organic frameworks (COFs) for loading Pd NPs. The quickly formation of a transition state, the highly dispersed Pd NPs and the advancedly spatial confinement effect were achieved by coupling Fe base synergistic active components, electron-oriented anchoring with controlling pore scale, respectively. Most notably, as a proof-of-concept application, the high catalytic activity of NH2-MIL-101(Fe)@Pd@COFs(3 + 3) in catalysis is elucidated for Suzuki-Miyaura coupling reaction by the broad scope of the reactants and the preeminent yields of the products, together with excellent stability and recoverability. With this strategy, the mechanism of Suzuki-Miyaura coupling reaction was verified by examining the catalytic activity. We hope that our approach can further facilitate the study of the design and use of functional MOFs@Pd@COFs materials.

Adequate light absorption and high carrier separation/transfer efficiency are central to elevate the development of highly efficient photocatalytic hydrogen evolution. Herein, a unique nano heterostructure is constructed by translocating 0D CdSe@(Zn, Cd)Se@ZnS quantum dots (CSS QDs) into the 3D hollow spherical graphite carbon nitride (SCN). The ultrafast TA spectroscopy and electrochemical measurements were measured to reveal the enhanced surface dependent electron transfer efficiency. Besides, the density functional theory (DFT) calculations further explained the mechanism of electrons transfer between interfaces. As expected, benefiting from the structural advantages of SCN and the channel-driven effectiveness produced by a step-accelerated system which is composed of (Zn, Cd)Se and ZnS double-shell layers of CSS QDs, the optimal hydrogen evolution rate of the prepared material in the photocatalytic hydrogen evolution reaction reached 132.5 μmol h−1, which was 7.6 times higher than that of the pure SCN under visible light irradiation. This work provides a novel avenue into the construction of nano heterostructure for solar hydrogen evolution.

A high-efficiency and easy-available approach was developed to obtain a ternary heterojunction composites with advanced hydrogen evolution reaction (HER) performance under visible light by water split. PdAg bimetallic nanoparticles make a close contact interface between g-C3N4(CN) and Zn0.5Cd0.5S(ZCS). Under visible light irradiation, CN and ZCS are both excited to generate electron-hole pairs, PdAg bimetallic nanoparticles act as a bridge between CN and ZCS. Not only can the photogenerated electrons from CN be captured, but they can also be quickly transferred to the surface of ZCS and participate in the photocatalytic reaction to release H2, and the recombination of charge carriers between the contact interface of ZCS and CN can be significantly inhibited. In addition, the thin CN layer reduces the photocorrosion of the ZCS and enhances the specific surface area of the composite material. After testing, the composite material with 30 wt% ZCS and 4 wt% PdAg demonstrates hydrogen evolution performance, up to 6250.7 μmol g−1h−1, which is 753 times the hydrogen evolution rate of single-component CN and 12.6 times of ZCS/CN. Compared with single-component and two-component photocatalysts, the ternary ZCS/PdAg/CN photocatalyst achieves significantly enhanced photocatalytic activity.

Carbon nitride, considered to be a promising photocatalyst, still has much room to increase the catalytic performance owing to the slow charge transfer and limited light harvesting ability. Herein, carbon doping carbon nitride with hollow tubular structure was successfully developed by using melamine and sodium alginate as precursors via a simple hydrothermal calcination method. The effects of carbon content on the structure and photocatalytic activities of as-obtained carbon nitride were researched in detail. The hollow tubular structure can assist the enhancement of specific surface area, increase of visible light harvesting ability and enhancement of electron transport ability. Simultaneously, carbon doping can adjust the photoelectric performance and band structure of carbon nitride due to the generation of delocalized big π bonds to enhance the photocatalytic activities. The catalytic performance of as-obtained carbon nitride is estimated by hydrogen evolution reaction. And carbon doping carbon nitride with hollow tubular structure accounts for 3 times and 2 times promotion than pristine CN in hydrogen evolution rate under λ > 420 nm and λ > 400 nm, respectively. Especially, the sample CN-40 shows a highly enhanced hydrogen generation efficiency of 1210.3 μmol h-1 g-1, which should be inseparable from the function of carbon doping and hollow tubular structure.

Modifying the texture of carbon nitride to adjust its physicochemical performance is a fascinating method for achieving high photocatalytic activity. Herein, we synthesized 3D porous carbon nitride with ultra-thin nanosheets by using cyanuric acid-melamine supramolecular and ionic liquid as precursor and template, respectively. The ionic liquid adjusts the morphology of materials and induces the carbon residue into the porous channels owing to its incomplete degradation. The 3D porous framework makes carbon nitride reflect the enhanced surface area, exposes adequate reaction sites, and offers a pathway for charge transport. And carbon residue and ultra-thin nanosheets further promote the photogenerated carriers transport and reduce the recombination rate of charge carriers. Consequently, 3D porous carbon nitride with ultra-thin nanosheets exhibit outstanding and stable hydrogen evolution under visible light irradiation. Significantly, as-fabricated sample CN-100 reflects an improved H2 generation rate, up to 17,028 μmol h−1 g−1, which is 12 times higher than that of CN (1412 μmol h−1 g−1). The present work offers a unique synthesis strategy to develop the novel photocatalyst with efficient photocatalytic performance.

Photocatalytic hydrogen evolution reaction (HER) provides a new way for the development of clean energy. Herein, a high-performance peony-like 3D structure S-doped carbon nitride (SCNx) with a large specific surface area was synthesized through a universal and non-thermal polymerization template-free approach. As an additional component, the introduction of trithiocyanuric acid in the raw material led to the formation of supramolecular intermediates through hydrogen bond self-assembly, and the sulfur was introduced into the framework of g-C3N4 subsequently. The charge separation lifetime of SCNx was studied by transient absorption spectroscopy, and the reason for its excellent optical performance was revealed from a dynamic perspective. Furthermore, the resulting SCNx composite material shows significant photocatalytic hydrogen release performance under visible light irradiation. In particular, the photocatalytic hydrogen rate of SCN1.0 reached 567.7 μmol/h, which was almost 53 times that of BCN, and was also 2.3 times that of SCN0 obtained by the binary self-assembly of melamine and cyanuric acid. Our finding advances the application of simple, environmentally friendly, and scalable strategy for the synthesis of high-performance sulfur-doped g-C3N4 photocatalysts.

Improving the non-magnetic low-frequency electromagnetic (EM) wave performances of common microwave-absorbing materials is yet very difficult and depends on the assistance of structural design to realize tremendous microwave reflectance absorption in a limited space. Herein, a biomimetic three-dimensional coral reef-like graphene oxide (GO)@TiO2 composite framework was prepared with porous TiO2–C inlaid subunits derived from MIL-125 (Ti), which provided an effective platform for concentrating two unusual structures of TiO2 and carbon sources into single particles. The formation mechanism of the material was analyzed in detail. Compared with GO@TiO2/TiO2–C composite materials at varying mass ratios, the minimum RL of GO@TiO2/TiO2–C-15 is −64.4 dB at 7.4 GHz, and the intensity of −25 dB (>99% energy absorption) can be improved at different thickness, which exhibits an excellent low-frequency EM absorption behavior. Simultaneously, GO@TiO2/TiO2–C-15 has obvious extended performances, including antimicrobial activities and low infrared emissivity, which demonstrate the versatility and application potential of non-magnetic low-frequency microwave absorbers in wearable devices and other fields. The new material is beneficial to reducing the EM waves-caused threat to human health in communication band and to attaining the sustainable utilization of EM waves.

Carbon nitride is found to be an outstanding metal-free photocatalyst for photocatalytic hydrogen evolution. However, carbon nitride suffers from insufficient light absorption and wide band gap, wh...

Nickel–iron foam (NFF) has high air permeability and a high specific surface area because of its connected pore structure and high porosity, making it an ideal catalyst support material. However, it is challenging to effectively utilize metal ions in the NFF to prepare new advanced electrocatalysts without introduction of metal species. Here, we demonstrate that activated metal ions in NiFe foam serve as the support and metal sources for in situ synthesis of NiFe bimetal–organic frameworks (NFF-MOF). Specifically, by further acidification to activate NiFe metal ions on the NFF backbone, and then to generate active NFF-MOF species through the participation of the organic ligand, the resulting NFF-MOF material exhibits significantly improved electrocatalytic performance toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with ultralow overpotentials of 81 and 250 mV at a current density of 10 mA cm–2, respectively. Density functional theory calculations and experimental results suggest that the NFF-MOF from the in situ-activated NiFe foam promotes transport and separation of charge because of highly uniform dispersed metal sites, high porosity, and an ordered 3D skeleton structure, thus accelerating the electrochemical HER and OER. This work brings new insights for the development of next-generation high-efficiency electrocatalysts.

Porous cellulose films have been reported as sustainable and highly-efficient non-power radiative cooling (PRC) materials but are still challenged by their insufficient atmospheric window (AM) emissivity and complex preparation technology. Herein, bio-mimetic skin structure inspired 3D porous cellulose acetate hybrid hollow AlPO4 (3D PCA/h-AlPO4) nano-laminated PRC film is creatively fabricated by a proposed solvent polarity matching strategy. Owing to the ultra-rapid extraction of high-quality solvent NMP by water relying on their stronger matching polarity, the PRC film self-forms ultra-rapidly within 5 min and is composed of skin-like wrinkle surface, porous matrix, and dense nanolayer. The wrinkle surface and dense h-AlPO4 nanolayer has been demonstrated to have higher atmospheric window emissivity (∼94.7% and 96.6%) than the smooth surface (88.7%). The self-formed uniform cavities of about 2 μm can contribute to a high solar reflectivity (∼97%). As proof of concept, the bio-structural film is used for all-day cooling under different atmospheric radiations, and about 13.5 °C/5 °C (daytime high solar irradiance of 988 W m−2) and ∼1.5 °C/0.5 °C (nighttime) temperature reduction is realized at low/high (12 °C/35 °C) environment temperatures, respectively. We believe the bio-structure design and ultra-rapid film-formation strategy would inspire the development of polymer-based PRC materials for the highly-efficient energy saving applications.

It is essential to manufacture microwave absorbers with strong absorption as well as tunable absorption bands at a low filler content. However, it remains challenging for pure biomass material to reach this goal without loading other components. MoSe2, as a transition metal chalcogenide with semiconductor properties, has emerged as a potential microwave absorber filler. Herein, bacterial cellulose (BC)-derived carbon nanofibers/MoSe2 nanocomposite was fabricated and phosphoric acid was used to dope phosphorus in BC, in which MoSe2 microspheres were dropped on the BC network like a dew-covered spider web. This unique network structure enhances conductive loss and multiple reflections of the incident wave. The collocation of BC and MoSe2 is helpful to impedance match and introduces interfacial/dipolar polarization loss; moreover, the P-doping of BC helps to tune the absorption bands. Overall, the optimal reflection loss of undoped one reaches −53.33 dB with only 20 wt.% filler content, whose main absorption peaks focus on X-band. Interestingly, after the P-doping of BC, the main absorption peaks move to Ku-band and the optimal reflection loss gets stronger (−66.84 dB) with the same filler loading. Strong absorption and tunable absorption bands can be realized, and thus wide frequency range is covered. This work is expected to enlighten future exploration of biomass carbon materials on high-performance microwave absorption materials.

Transition metals are increasingly attracting interest in electrocatalysts for use in water decomposition due to their excellent catalytic activity and stability. Simultaneously, metal-organic frameworks with designable metal ion centers and organic ligands are the promising precursors for the one-step synthesis of metal encapsulated in carbon composites for alkaline hydrogen evolution reaction (HER). Herein, we report the successful construction of Co-CoO/ZnFe2O4 encapsulated in carbon nanowires (Co-CoO/ZnFe2O4@CNWs) by annealing as-synthesized nanowire Co/Zn/Fe-MOF at 400 °C in N2. This structure provides the rich defect sites and active centers, and the synergy of Co, CoO and ZnFe2O4 lead to efficient hydrogen evolution when the composite is used as a catalytic electrode for HER in 1.0 M KOH. The catalyst shows a low initial overpotential (97 mV) and a small Tafel slope (138 mV dec−1), and the overpotential at 10 mA cm−2 is only 226 mV. In addition, this composite material exhibits excellent long-term durability even after 1000 cycles. It is expected that it is a potential alternative catalyst for rational utilization in the field of electrolytic water decomposition.

This article has presented a physics-based model which replicates the failure of SiC MOSFET under short-circuit (SC) case. The model is constructed on the base of the traditional circuit model of SiC MOSFET by introducing two leakage current mechanisms; one is the leakage current between the drain and the source, and another is the gate leakage current. Furthermore, the carrier mobility characterized with trapped charges at the interface of SiC/SiO2 is adopted. The failure model had been validated against the experimental results. With the developed failure model, the failure mechanism of SiC MOSFET under a SC event is analyzed; the impact of interface trapped charges on the SC performances of SiC MOSFET is exploited. Moreover, the SC failure for SiC MOSFET with different OFF-state gate voltages has been addressed; the behavior of interface trapped charges has been analyzed.

Green and facile strategies for fabricating hollow microwave absorption materials without harmful solvent etching have attracted extensive attention but still remain a challenge. Herein, the cubic hollow Co/N/C@MnO2 composites were prepared through metal–organic frameworks (MOFs) self-templated eco-friendly method with polydopamine (PDA) as carbon source and hierarchical MnO2 nanosheets were incorporated for improving impedance mismatch caused by excessive permittivity in Co/N/C. Such a uniform distribution of Co particles in the N-doped porous carbon matrix, in association with the hollow structure and hierarchical MnO2 nanosheets, endow the composites with enhanced electromagnetic (EM) wave absorption. Notably, Co/N/C@MnO2 sample with a filler loading of 15 wt% shows extraordinary EM wave absorbing performance with the minimum reflection loss (RL) of −58.9 dB and wide absorption bandwidth of 5.5 GHz. Several minimum RL values at a thickness in the range of 1.5–5 mm, are below than −50 dB, outperforming many similar materials reported previously. Besides, the possible microwave absorption mechanism was elaborated in detail. Our work provides an environmentally friendly and facile route for fabricating MOFs self-templated hollow carbon-based microwave absorbers.

Enhancing the kinetics of electrocatalytic water splitting, including the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), under alkaline conditions is of key importance for producing high purity and renewable hydrogen on a large scale. Owing to their unique structural features, two-dimensional (2D) heterostructures have been regarded as promising next-generation electrocatalysts for overall water splitting. Herein, we successfully synthesized three-dimensional (3D) flower-like Co–Ni–P/MoS2 heterostructural hybrid spheres assembled from heterostructural 2D nanosheets. Benefiting from well-exposed interfaces and favorable diffusion channels, the as-prepared 3D flower-like Co–Ni–P/MoS2 heterostructural hybrid spheres manifest excellent overall water splitting performance in an alkaline solution with a low Tafel slope of 71 and 41 mV dec−1 for oxygen and hydrogen evolution reactions, and show significantly improved long-term durability. Furthermore, the 3D flower-like Co–Ni–P/MoS2 heterostructural hybrid spheres used in both the anode and cathode show a low cell voltage of 1.53 V at a 10 mA cm−2 current density. Using DFT calculations, we found the outstanding chemisorption of hydrogen and oxygen-containing intermediates making Co–Ni–P/MoS2 heterostructures an efficient bifunctional overall electrochemical water splitting catalyst. In summary, this work opens up an important direction for exploring efficient and durable bifunctional electrocatalysts for the overall water splitting.

We report a facile one-pot solvothermal synthesis of NiPd alloy homogeneously encapsulated between reduced graphene oxide sheets and N-doped carbon layers (rGO@NiPd@NC) with sandwich structure. In this study, dopamine served as both carbon-nitrogen source and green reagent, which cannot only form N-doped carbon layers encasing metal nanoparticles through high-temperature roasting but also co-reduce metal ions to form NiPd alloy. The rGO@NiPd@NC nanocomposite exhibits enhanced hydrogen evolution reaction (HER) activity with a small overpotential of 56 mV at 10 mA cm−2 and a Tafel slope approaching 33 mV dec−1 in acidic aqueous media, which are similar to the HER activity of commercial Pt/C catalyst (52 mV at j = 10 mA cm−2; Tafel slope, 31 mV dec−1). Additionally, the electrocatalyst which reveals excellent electrochemical stability is reflected in that the polarization curve shows negligible difference after 1000 cycles and the current density only slightly decreases within 20 h test, providing more possibilities for practical application in the future.

Achieving sustainable energy technology with outstanding performance and clean materials for overall water splitting, while fascinating, still include many challenges. Herein, the masterly CoNi2S4@CoS2/NF 3D microspheres assembled by peapod-like nanorods with a mass of CoS2 particles are successfully prepared on nickel foam. The well-preserved 3D porous materials with unique heterostructure have various merits including more electronic channels, small electrons transfer resistance and open interior space. Besides, the unique peapod-like structure endows the catalyst plentiful, dispersive and exposed reactive sites, which is vital important to significantly increase the electrochemical performance. Notably, the as-prepared CoNi2S4@CoS2/NF catalysts achieve optimized electrocatalytic activity for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) at low overpotentials of 259 mV and 173 mV while deliver 10 mA cm−2 current density, respectively. It can be anticipated that it is a potential alternative catalyst for rational utilization in electrolytic water splitting fields.

Although plasmas commonly present as electrical neutrality, for plasma jet plume at atmospheric gas pressure, it might appear nonneutral polarity due to plasma bullet being consisted of a large amount of electron avalanches. In this paper, the polarity transition and the ionization enhancement of atmospheric argon plasma jet plumes generated by the repetitive microwave pulses are studied. Three interesting phenomena have been found despite of discharges either with or without the hairpin metal wire, including: 1) a potential voltage pulse with positive polarity invariably arises steeply at each moment of power on; 2) high-speed photograph images show that there are ionization enhancements happened twice in each pulsed periods; and 3) ahead of the confluence point, the polarity transits from negative to positive while behind of this point, its positive polarity changes into the negative one. Moreover, the experiment results and electromagnetic simulations suggest that the theories of guided negative ionization wave and microwave resonant discharge excited by surface plasma polaritons should be used to interpret the spatial–temporal discharge process of the proposed microwave plasma jets.

A core-shell structure Au-based catalysts mSiO2/Au/Co3O4 HS were successfully derived from in-situ growth ZIF-67 hollow spheres, which were synthesized by a one-step soft template method. The samples were characterized by SEM, TEM, EDX, XPS, XRD and BET to confirm its successful preparation and structural features. The catalytic performance of the catalysts were evaluated by liquid phase oxidation of benzyl alcohol to benzaldehyde with O2 as the oxidant under alkaline conditions. The experimental results illustrated that reaction conditions, including effect of catalyst amount, oxygen flow rate, reaction temperature and reaction time, were optimized to be 40 mg, 50 ml/min, 140 °C and 5 h, respectively. Meanwhile, 55% conversion of benzyl alcohol and 84% selectivitiy to benzaldehyde together with the excellent reusability and stability were achieved under optimal reaction conditions, which was attributed to the core-shell structure leading to the encapsulation of Au NPs and provision of multiple active reaction interface. Based on the intermediates formed from the de-protonation of substrate, a plausible oxidation reaction mechanism with mSiO2/Au/Co3O4 HS catalysts was tentatively proposed to study the relationship between structure and catalytic performance.

A facial, template-free and green strategy was developed to prepare C-doped hollow spherical g-C3N4 derived from supramolecular self-assembly of melamine, glucose and cyanuric acid. Especially, the precursors were tightly connected by hydrogen bonds, wherein glucose was served as a source of doped carbon. Spectroscopic and electrochemical analysis confirmed that the endmost nitrogen was replaced by the doped carbon to combine two melon parts, leading to the possible existence of the delocalized big π bonds in the system. Moreover, the GCN-x not only maintained the excellent properties of the hollow sphere, such as high surface area, moderate porosity and short charges diffusion distance, but also overcame the drawbacks of low visible light response and high electron-holes recombination rate from bulk g-C3N4. Thereby, the visible light utilization rate and the photogenerated electron-holes separation efficiency of the catalyst were improved. The highest hydrogen yield of 305 μmol h−1 from GCN-0.2 was 28.5 times that of bulk g-C3N4. Finally, a possible mechanism underlying the photocatalytic performance of C-doped g-C3N4 hollow spheres was proposed tentatively.

Carbon doped honeycomb-like graphitic carbon nitride (g-C3N4) was prepared by one-step thermal polymerization, which derived from chitosan as a carbon source together with the melamine-cyanuric acid complex as a supramolecular precursor. Interestingly, the carbon doped g-C3N4 displayed an increased specific surface area and a more negative conduction band energy level, which not only provided a large number of reaction sites for the photocatalytic hydrogen production, but also effectively enhances the separation of photogenerated electrons-holes. And the experimental results showed that the hydrogen evolution rate of the optimal sample was as high as 320 μmol·h−1, which is 29.10 times than that of bulk g-C3N4 (11 μmol·h−1). More importantly, this work may provide a promising idea for the design of efficient g-C3N4 by controlling the material morphology and combining the electronic modulation strategy.

The first snail shell-shaped helical polyacetylenes (SHPAs) were synthesized from the copolymerization between l-serine-grafted propargylamine (LSA) and propargylamine (PA). The novel structure was obtained at the monomer input proportion of 50%. The monomer (LSA) and copolymers (poly(LSAm-co-PAn)) were characterized by 1H nuclear magnetic resonance, Fourier transform infrared spectroscopy, ultraviolet visible spectroscopy, circular dichroism and transmission electron microscopy. The infrared emissivity of poly(LSA50-co-PA50) investigated at 8–14 μm was 0.451, which was much lower than the other copolymers. This was because the poly(LSA50-co-PA50) could form the obvious intramolecular interaction and self-assembled to a snail-shell shape by intermolecular hydrogen bonding in MeOH solution. Meanwhile, the conjugation performance of the main chain was enhanced. Consequently, the abundant hydrogen bonds formed through N–H and C=O bonding and the strong conjugate properties both could decrease the unsaturation degree, as well as change the heat conduction mode in the molecules, thereby reducing the infrared emissivity. This strategy provided a new direction to achieve the controllable infrared stealth.

Herein, a novel strategy is established to synthesize Mo-doped graphitic carbon nitride (g-C3N4) with excellent photocatalytic activity through a green approach of biological template. The addition of biotemplates provides a microenvironment for the formation of hydrogen bonds in which the flower-like g-C3N4 is formed by self-assembly between precursors, which not only increases the specific surface area of the material but also exposes more catalytic activity edge. Benefiting from the non-localized of Mo(VI) 4d orbital, Mo-doped g-C3N4 constructs a suitable band structure and a built-in electric field that promotes electron delocalization, which improves the absorption range of visible light and separation efficiency of photo-generated electron-hole pairs. Subsequently, a possible chelation-hydrogen bond coordination mechanism was proposed based on the characterization results of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) and 15N solid-state NMR (15N NMR). As a result, the π-conjugated system of g-C3N4 was extended by forming a chelate centered on Mo(VI). Photocatalytic hydrogen evolution (PHE) showed that the optimal hydrogen evolution rate of Mo-doped g-C3N4 was as high as 2008.9 umol/g·h, which was 9.6 times than that of bulk g-C3N4.

Carbon nitride is a promising candidate for photocatalysis but exhibits the limited activity due to the poor mass rate and insufficient light harvesting properties. Herein, an efficient synthesis a...

Hydrogen is a source of sustainable and clean energy poised to replace fossil fuels. Bifunctional electrocatalysts are actively pursued to simultaneously drive the two key reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), for hydrogen production by electrolysis water. One of the most promising candidates based on bimetallic layered double hydroxide salts (LHSs) and cobalt-based organic framework (ZIF-67) suffer from poor interface coupling. Herein, we present a new approach based on fusing NiCo LHSs nanowire arrays with ZIF-67 to fabricate three-dimensional flower-like structures on a Ni-Fe foam support. To improve interfacial coupling and catalytic performance, simple oxidation, carbonization, sulfurization, and selenization are performed to study the effects of different post-treatments and discover the optimum bifunctional electrocatalysts. The optimized S-doped catalyst reveals the highest electrocatalytic characteristic quantified by the low overpotentials of 170 and 100 mV for OER and HER at 10 mA cm -2 in 1 M KOH, respectively. This outstanding electrocatalytic property is ascribed to strong interfacial coupling between the NiCo-LHSs and ZIF-67 derivatives, as well as the rational electronic structures, dense catalytic active sites, and large specific surface area. This work opens new prospects for fabricating efficient and low-cost electrocatalysts for renewable hydrogen energy production.

In this study, a highly efficient and simple in situ one-step hydrothermal process is demonstrated to synthesize the yolk-shell polysiloxane@3D flower-like hollow Mg Al layered double hydroxides (LDH). The morphology analysis further confirmed its unique structure and the polysiloxane@3D flower-like hollow Mg Al LDH was 2–3 μm in diameter with 100 nm shell thickness. Moreover, solvent-free UV curing process was employed to prepare the optical diffusers based on the polysiloxane@3D flower-like hollow Mg Al LDH and the optical properties of the diffusers were investigated in detail. Interestingly, suitable light transmittance, good diffusion capacity, and low incident angle dependence can be achieved by the as-prepared films. Especially, when the concentration of the fillers was up to 15 wt%, the optical diffusers possessed superior diffusing properties. Therefore, this study may help to open up a new door in developing light scattering materials for the high-performance optical diffusers.

A series of fluorine-silicon block urethane acrylates (PSi-FMPG-IPDI-HEMA) were synthesized from hydroxypropyl-terminated polysiloxane (PSi), newly-prepared fluorodiol (FMPG), isophorone diisocyanate (IPDI) and hydroxyethyl methacrylate (HEMA). Their molecular structures were characterized by Fourier transform infrared and gel permeation chromatography. The compatibility of the oligomers with HFMA was validated using UV–vis transmittance analysis. The thermal stability, water and chemical resistance, contact angles and anti-adhesive performance of the films were measured. It was found all the films had good thermal properties, and excellent water and chemical resistance. The FMPG content affected the surface energy and anti-adhesive performance of the films. The films with more FMPG presented lower surface energy, lower peel strength, and higher residual adhesion. More importantly, the release films designed based on the fluorine-silicon block urethane acrylates had tremendous application potential.

The exploration of high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) is of great significance for sustainable energy conversion applications, yet it remains a grand challenge. Herein, a facile and rapid strategy to synthesize ultrafine PtNi nanoparticles (NPs) anchored on N-doped graphene (rGO(N)) (labeled as PtNi/rGO(N)) at room temperature is demonstrated. (3-Aminopropyl) triethoxysilane (APTES) is selected as an effective nitrogen source to form two kinds of nitrogen (doping N and amine N) simultaneously for fabricating a rGO(N) matrix during the chemical reduction process. Benefiting from the bimetallic synergistic effect and strong metal–support interactions, this composite is expected to accelerate H+ adsorption and H2 desorption and reduce the transport resistance of electrons and hydrogen intermediates. As a consequence, the PtNi/rGO(N) with ultralow Pt loading amount (1.2 μg per electrode area (cm2)) exhibits extraordinary catalytic activity with a small overpotential of 98 mV at a current density of 10 mA μgPt−1 and an exceptional Tafel slope of 42.7 mV dec−1 for HER, exceeding the incumbent commercial Pt/C catalyst. Moreover, the PtNi/rGO(N) also displays excellent stability with negligible current degradation during a continuous operation for 20 h. The present work would be proposed as an elegant platform toward the exploration of efficient HER electrocatalysts for various renewable energy conversion applications.

Developing highly active electrocatalysts with rich oxygen vacancies and precisely distributed metal sites holds exceptional promise for various renewable and sustainable energy technologies. However, the great challenge is to ensure the stability of oxygen vacancies (VO) during the oxygen evolution reaction (OER) process. Herein, we implement an innovative approach to produce a highly active and stable OER electrocatalyst by plasma-enabled Fe doping of Co-based 2D metal–organic framework (MOF) nanosheets, followed by a carbonization process to fabricate unique triangular-shaped “cheese-like” Fe/Co–carbon nanosheets with a mesoporous structure, and densely and evenly distributed reactive centers, and without damaging the frameworks. The O2–Ar radio frequency (RF) plasma ensured two critical effects, namely oxygen vacancy generation, and forming and modifying the oxidation states of the catalytically active metals in the framework leading to high OER performance. It is shown that filling the oxygen vacancies with Fe heteroatoms helps tune the atomic sites of the two metals in the MOFs and achieve a unique heterostructure where electron currents can be directed between metal sites of different oxidation states. Benefiting from the demonstrated unique advantages of our plasma-enabled approach, the optimized Fe1Co3/VO-800 exhibits a significantly enhanced OER performance and long-term stability, evidenced by a low overpotential of 260 mV at 10 mA cm−2 and a small Tafel slope of 53 mV dec−1. This work provides a new effective approach for the development of next-generation electrocatalysts for diverse applications in environmental and energy fields.

Improving the spatial resolution of remote sensing satellites has long been a challenge in the field of optical designing. Although the use of large-aperture reflective mirrors significantly improves the resolution of optical systems, controlling the film thickness uniformity remains an issue. The planetary rotation system (PRS) has received significant attention owing to the excellent uniformity of the coating applied to the large-aperture reflective mirror. However, the development of the PRS remains hindered by a lack of research on its properties and the design method of the shadow mask. To address this, we performed a theoretical analysis of the distribution of film thickness and uniformity in the PRS, which is impacted by parameters of geometric configuration in the vacuum chamber. We present a film thickness expression based on Knudsen’s law and the geometric configuration of the vacuum chamber that incorporates an additional shading function. Moreover, the variation of uniformity in the standard and counter PRSs was elucidated by changing the location of the evaporation source. Finally, a fixed-position shadow mask, which was obtained by theoretical design, allows the nonuniformity of the concave reflective mirror (with a 700 mm aperture) to reduce from 2.43% to 0.7%, highlighting the importance of initial shape design.

2D transition metal carbides and nitrides (MXenes) have gained much interest in microwave absorption. However, the high conductivity of MXenes results in inferior absorption performance. To solve this problem, Cellulose nanofiber (CNF) is compounded with MXenes to build membranes with biomimetic structures. CNF not only contributes to adjusting the electromagentic parameters, but also enhances the microwave attenuation and regulates the absorption band. In this work, nacre-like and loofah-like carbonized CNF/MXenes membranes were successfully prepared. The self-assembly of CNF and MXene avoids the impedance mismatch, and the biomimetic structures enhance conductive loss, polarization loss and multiple reflection. The results show that nacre-like carbonized CNF/MXene membrane (CCM) exhibits absorbing performance with the minimum reflection loss (RLmin) of −42.2 dB and the Effective absorption band (EAB) of 7.12 GHz. Meanwhile, the absorption peaks are mainly concentrated on X-band. Further, as the morphology changes to porous layers, the RLmin of loofah-like CCM increases to −63.8 dB, whose EAB is 7.32 GHz at 2.5 mm, and the main absorption peaks shift to Ku-band. Besides, the possible absorption mechanism of biomimetic composite membranes has been expounded. This work provides a versatile strategy for CNF/MXene composite membrane with biomimetic structures on excellent and tunable microwave absorption performance.

Fabrication inside transparent materials using femtosecond laser has important applications in optical storage, microfluidic devices, and other fields. However, the manufacturing efficiency and quality are limited due to the Rayleigh-length of Gaussian beam and the saturation effect in multi-pulses processing. In this paper, plasma distribution and morphology inside PMMA was modulated by adjusting the focus depth (0~ 200 μm) of femtosecond laser single pulse, which realized the fabrication of modification lines with controllable length and high efficiency. Ultrafast pumpprobe imaging system was used to investigate the evolution of filaments and shockwave inside PMMA during processing. The results showed that the filaments and shockwave inside PMMA transformed from the combination of hemispherical shockwave and filaments into only filaments gradually. Besides, it was observed that the length of filaments extended from 50 μm to 325 μm with the increasing focus depth. The simulation of finite-different time-domain was executed and the results agreed well with the observation results. It indicated the changed optical field distribution inside PMMA caused by different focus depth resulted in the corresponding changes of filaments and the effects of self-focusing and spherical aberration dominated in the mechanism of filaments extension on both sides. The morphology of structure processed inside PMMA was further characterized by optical microscope. It showed that uniform modification lines can be fabricated by single pulse with all focus depth and the length of which increased from 73 μm to 135 μm. These controllable modification lines have great potential in fields like optical waveguide, optical storage and hologram.

A series of novel water-soluble amphiphilic copolymers containing ciprofloxacin (CPF) and quaternary ammonium salts were prepared by the free-radical copolymerization of methacrylate monomers with CPF, quaternary ammonium salt (QAS) monomers and butyl acrylate (BA). The copolymers were characterized by 1H-NMR, charge density and UV measurements. The antimicrobial activities of the copolymers, based on the minimum inhibition concentration (MIC) against Escherichia coli (E. coli), varied with hydrophobic BA content in the copolymers. The incorporation of the antimicrobial moiety ciprofloxacin further enhanced the antibacterial activities of the copolymers, reducing the MIC to 4.0 ppm. The UV260 absorption measurements were applied to reveal the dynamic antimicrobial process of the copolymers. The results of inhibition zones and shaking flask methods of antimicrobial-modified fibers showed that the copolymers had excellent antimicrobial activities when applied to cellulose fibers. In the presence of 2 wt% (based on oven-dried fibers) of the copolymer, the growth inhibition reached 100%.

Although metal chalcogenides have been widely utilized as microwave absorbers, it remains a challenge for them to achieve efficient and broadband absorption performance with low filler content. Herein, a series of rime-like carbon paper@Bi2S3 hybrid structures are manufactured by a facile one-step solvothermal process, whose morphology and microwave absorption properties also can be easily adjusted by the dosage control of raw materials. The Bi2S3 clusters are grown densely on the surface of carbon paper fibers, like the rime in winter. The collocation of carbon paper and Bi2S3 is beneficial to impedance matching and synergistically enhances microwave absorption capability based on various attenuation mechanisms, including interfacial/dipolar polarization loss, conduction loss, and multiple reflection. At a low filler content (only 5 wt%), the optimal reflection loss among these composites is −56.63 dB at 8.84 GHz with 3.3 mm thickness, and the broadest efficient absorption bandwidth is 7.32 GHz with a thickness of 2.4 mm, covering the whole Ku band. By adjusting the thickness, the total covered frequency range reaches 13.36 GHz (83.5% of 2–18 GHz). The as-prepared materials have unique microstructure and exhibit strong and broadband absorption performance with thin thickness and low filler content, enlightening future exploration of metal chalcogenides on high-quality microwave absorbers.

Lightweight and compatible metal-organic framework (MOF)-derived carbon-based composites are widely used in electromagnetic (EM) absorption. Their combination with laminated TiO2-C (derived from Ti3C2T x) is expected to further strengthen the EM attenuation ability. Herein, novel laminated Co/TiO2-C hybrids were derived from Ti3C2T x/Co-MOF using heat treatment. Compared with pristine MOF-derived carbon-based composites, the EM absorption ability of Co/TiO2-C was improved by multiple reflections between multilayered microstructures and the improved polarization loss (due to the heterogeneous interfaces, residual defects, and dipole polarization) and the strengthened conductivity loss caused by the carbon layers. Specifically, for the Co/TiO2-C hybrids at thicknesses of 3.0 and 2.0 mm, the optimal reflection loss (RL) was -41.1 dB at 9.0 GHz and -31.0 dB at 13.9 GHz, with effective bandwidths (RL ≤ -10 dB) of 3.04 and 4.04 GHz, respectively. This study will underline the preparation of carbon-based absorbing materials starting from MXene/MOF hybrids.

Hollow microtubule structured nano-/micromaterials of hollow tubular g-C3N4 (TCN) enwrapped with nanosheets were fabricated by a three-step method. By calcining NiCo-layered-double-hydroxides/tubular-cyanuric acid-melamine (NiCo-LDH/TCM) precursor prepared through using 2-methylimidazole as precipitant and methanol as solvent, the as-prepared NiCo-alloy@tubular-g-C3N4 (NC@TCN) shown excellent microwave absorption in the frequency range of 2–18 GHz. The optimal reflection loss (RL) of −35.63 dB was observed at 5.00 GHz and an effective absorption bandwidth of 4.80 GHz at a matching layer thickness of 2.0 mm. Our results indicated that the deposition of NiCo-alloy nanoparticles on g-C3N4 microtubule was an efficient way to fabricate g-C3N4-based high-performance microwave absorbers.

Developing bifunctional electrocatalysts of high-efficiency and new structures for overall water splitting are highly desirable and ongoing challenge. Herein, CoxNi10-x layer double hydroxide salts with controllable structure and morphology induced by 2-methylimidazole to derive ZIF-67 on Ni/Fe foam is reported. The as-prepared 3D CoxNi10-x layer double hydroxide microspheres are constructed by self-assembly of 2D nanoflake and 1D nanorod with ZIF-67 particles due to the double influence of Ni and 2-methylimidazole. It is discovered that the Ni and 2-methylimidazole can simultaneously modulate morphology and structure of CoxNi10-x layer double hydroxide to distinctly increase the electrochemical active surface area for exposing more accessible active sites. Notably, the 3D microsphere heterogeneous catalysis of the self-assembly combines the merits of low dimensions (1D and 2D) materials, providing high structural void porosity and fast charge transport channels. Particularly, the Co7Ni3 layer double hydroxide salts@ZIF-67/Ni/Fe foam exhibits the highest electrocatalytic activity with the lower overpotentials of 260 and 165 mV toward oxygen evolution reaction and hydrogen evolution reaction at current density of 10 mA cm−2, respectively. The outstanding activity originates from the strong electronic coupling between the 3D microsphere and ZIF-67. This work can bring a new prospect for fabricating highly-active and new structure electrocatalysts.

Metal-organic framework (MOF)-derived porous metal/C composites have drawn considerable attention from the microwave absorption field owing to their large pore volumes and surface areas. Exploring single-MOF-derived materials with high intensity and broadband absorption is largely needed but remains a challenge. Here, porous Co/ZnO/C (CZC) microrods were fabricated easily from cuboid-shaped heterobimetallic MOFs. CZC provides an efficient platform for integrating different semiconductors (ZnO), magnetic metal (Co), and carbon sources into one particle, which enhances the electromagnetic (EM) wave-absorbing ability. The carbonization temperature which is critical for EM parameters was studied in detail. CZC annealed at 700 °C outperformed those obtained at 600 or 800 °C in terms of microwave wave-absorbing properties. The reflection loss (RL) was optimized to -52.6 (or -20.6) dB at 12.1 (or 14.8) GHz with an effective bandwidth (RL ≤ -10 dB) of 4.9 (or 5.8) GHz at the coating thickness of 3.0 (or 2.5) mm. Such enhancement of EM wave-absorbing capabilities is ascribed to the well-built porous structure, dielectric loss, and magnetic loss. This work offers a new way to prepare porous magnetic metal/C composites with excellent microwave-absorbing properties starting from heterobimetallic MOFs.

In this work, g-C3N4 with different morphologies is prepared using melamine as precursor via self-assembly and calcination. Compared with pristine g-C3N4, the resultant materials possess thinner lamellar structure and abundant nitrogen defects. Hydrolysis of partial melamine occurs in a hydrothermal process, and a consequent supramolecular intermediate is formed between melamine and its hydrolysates via hydrogen bonding. In addition to enlarging the π–π conjugated systems of the polymer, the formation of intermolecular hydrogen bonds is also interesting for increasing the lifetime of fluorescence as well as for decreasing the recombination rate of electron–hole pairs. Optical absorption characterization indicates that the samples formed by surface self-assembly show remarkably extended light absorption in the visible-light region in comparison with the original g-C3N4. Under visible-light irradiation, all modified materials have outstanding photocatalytic activity, especially the optimally modified cataly...

The controllability of glass surface radiation is of great significance on regulating temperature for applications in energy conservation in residential buildings. In this work, nano-scale hybrid films with tunable surface radiation are successfully prepared via layer-by-layer assembly of exfoliated layered double hydroxide (LDH) nanosheets with In2O3 quantum chips covering the surface of glass substrates. In this hybrid system, the ultra-thin LDH nanosheets are exfoliated from hexagonal plate-like particles of Mg-Al-NO3- LDH nanosheets after anion-exchange of Mg-Al-CO32- LDH nanosheets. And In2O3 semiconductor quantum chips are obtained after an annealing treatment from In(OH)3 nanosheets which are prepared in sodium oleate/indium chloride hydrothermal system. The prepared LDH nanosheets and In2O3 quantum chips are assembled layer-by-layer onto glass substrates to form the multilayer films. Morphological and structural evolution of the hybrid films is investigated by X-ray diffraction (XRD) and UV–vis absorption spectra. The characterization results show that the hybrid films exhibit ordered tunable structures, which predicts that the infrared emissivity can be adjusted throughout the infrared spectrum. The surface radiation properties of the hybrid films are studied, and the results show that the number of the layers has a significance influence on the surface radiation properties of the films. Attractively, the hybrid films possess thickness-dependent surface radiation properties with the lowest infrared emissivity of 0.420. The nano-scale hybrid films obtained in this work show great tunability on infrared emission and illustrate to be good candidates for saving energy in the field of energy conservation buildings and smart windows.

Tunable and high-efficiency electromagnetic wave (EMW) absorption materials composed of a three-dimensional (3D) hierarchical reduced graphene oxide (RGO) aerogel network entrapped with TiO2/Ti3C2Tx hybrids were fabricated by a hydrothermal method and a mild chemical reduction treatment. The incorporation of the TiO2/Ti3C2Tx micronanoheterostructure and construction of the 3D well-designed hierarchical interconnected network can significantly reduce the agglomeration of RGO sheets together with the beneficial effect of a better impedance match. When the filler loading is 10 wt %, the maximum reflection loss of the composite aerogel reaches up to −65.3 dB with a matching thickness of 2.5 mm. Meanwhile, the effective absorption bandwidth (RL < −10 dB) is 4.3 GHz with the coating thickness of only 2.0 mm, and the tunable absorption bandwidth achieves at 13.74 GHz via modulating the absorber thicknesses in a range from 1.5 to 5.0 mm. The enhanced EMW absorbing performance is closely related to highly porous c...

Mesoporous carbon nitride with novel morphology has been successfully fabricated by using ionic liquid and supramolecular precursor cyanuric acid-melamine complex as the template and precursor, respectively. The texture of carbon nitride is controlled by adjusting the ionic liquid concentration and type. The results find that a disordered hollow carbon nitride box morphology with pores in the wall can be obtained under lower IL1 concentration. With increasing of ionic liquid content, the texture turns to be a layered structure. The disordered nanosheets and hollow tube with large pores in the shell can be fabricated by using IL-2 and IL-3 as templates, respectively. Besides, as-prepared mesoporous carbon nitride samples display the excellent light harvesting properties and fast separation rate of photogenerated carrier. Moreover, mesoporous carbon nitride CN-0.1 exhibits a higher photocatalytic hydrogen evolution rate (120.3 μmol h–1) under visible light irradiation owing to the special structure and the ...

Imidazole (IMI)-based polyethylene glycol monomethyl ether (MPEC-IMI) as a novel green corrosion inhibitor was synthesized to protect the Q235 steel in 0.5 M HCl corrosive medium at 318 K. The inhibition performance of MPEC-IMI was investigated by weight loss measurement, the electrochemical method (Tafel and EIS) and surface analysis (SEM and EDX). The results reveal that the MPEC-IMI shows enhanced anticorrosion performance for carbon steel, which is attributed to the formation of the adsorptive protection film on the surface, and the type of adsorption basically obeys the Langmuir monolayer adsorption. Furthermore, when the concentration of MPEC-IMI is 300 mg L−1, the corrosion inhibition efficiency can reach up to 92.00%. In support of further study of the corrosion inhibition behavior by virtue of quantum chemical calculation and molecular dynamics simulations, the results show that the MPEC-IMI molecule has high reactivity and strong interaction on the iron surface.

Graphite carbon nitride (g-C3N4), as a promising low cost, visible light driven conjugated polymer semiconductor photocatalyst, has attracted wide attentions from researchers. However, low light absorption efficiency and inadequate charge separation limit the potential applications of g-C3N4. This paper exhibits K-doped g-C3N4 prepared by a facile thermal polymerization with KBr as the K source. The experiments of photocatalytic hydrogen evolution demonstrate that KBr content strongly affects the activity of the catalyst. XRD, FT-IR, XPS, SEM, TEM, UV–vis diffuse reflectance spectra, photoluminescence (PL) characterization methods are used to study the effects of potassium on the catalyst performance. The results find that K-modified g-C3N4 has a narrower band gap and enhanced light harvesting properties. Moreover, the photocatalytic hydrogen evolution rate (HER) of the optimized K-doped g-C3N4 nanosheets (10 wt % KBr) reaches 1337.2 μmol g−1h−1, which is about 5.6 times in comparison with that of pure g-C3N4 (239.8 μmol g−1h−1). The doping of the potassium may increase the π-conjugated systems and accelerate the electron transport rate, then improve the photocatalytic properties. Based on the results of the analysis, a possible mechanism is proposed.