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Electrochemical catalysts for the hydrogen evolution reaction (HER) have attracted increasing attentions. Noble metal-free cocatalysts play a vital role in HER applications. Herein, a novel strategy to prepare a Ni2P/MoS2 cocatalyst through a simple hydrothermal-phosphorization method was reported, and the prepared cocatalyst was then loaded on an N-doped carbon substrate with excellent conductive performance. The large surface area of the carbon substrate provided many active sites, and the interface between Ni2P and MoS2 improved the catalytic performance for the HER. Compared with pure Ni2P catalyst and MoS2 catalyst, the prepared Ni2P/MoS2 cocatalyst exhibited enhanced catalytic performance. In addition, the results indicate that the prepared cocatalyst has a wide pH range and low onset potential values of 280, 350 and 40 mV in acidic, phosphate-buffered saline and alkaline solutions, respectively, and the corresponding Tafel slopes are 75, 121 and 95 mV dec−1, respectively. Density functional theory (DFT) was adopted to calculate the hydrogen adsorption free energy (△GH∗). The results showed that the interface between Ni2P and MoS2 reduced △GH∗, which was beneficial to the adsorption of hydrogen. Present preparation of cocatalysts with unique interfaces provides a new strategy for improving the catalytic performance of HER.

Biomass-based carbon aerogels have attracted significant research attention due to the wide range of raw material, low cost, and environmental friendliness. In this study, green and sustainable carbon aerogels have been prepared using starch as raw material. Potassium chloride and potassium carbonate have been selected as template and activator. Due to the joint action of potassium chloride and potassium carbonate, the starch-based carbon aerogels exhibit a specific surface area of 2367 m2 g-1 with ant-hole-like 3D network pore structure. The starch-based carbon aerogels have been further employed as the electrode material for supercapacitors. The specific capacitance of the carbon aerogels is 292.3 and 245 F g-1 at current densities of 1.0 and 10 A g-1, respectively. In addition, the starch-based carbon aerogels demonstrate excellent sorption ability for oil and organics as well as insignificant sorption ability for H2O, thus, indicating their potential use as optimal oil-water separation material.

Supercapacitors are promising for high power application in the recent years. In particular, the conversion of simple and available carbon materials into economic and high performance electrical devices receives excellent scientific and technological interest. This paper reports a one-step strategy for synthesizing hierarchical porous carbon derived from phenolic resin (PR), which is then used to configure electric double-layer capacitors (EDLCs). Here, a carbon material with a flexible porous structure, large specific surface area, and high graphitization degree is prepared using potassium ferrate (K2FeO4) to catalytically activate PR and to realize synchronous carbonization and graphitization. This method overcomes the disadvantage of time-consuming, high-cost, and environmentally unfriendly. In addition, the as-prepared carbon material has a high specific surface area (1086 m2 g−1) and a large pore size (3.07 nm), which can increase the transfer rate of electrolyte ions. The specific capacitance of the obtained electrode material is 315 F g−1 at 1.0 A g−1, and the optimized electrode material has an ultra-long cycle lifetime (capacitance retention rate is 96.3% after 10,000 cycles). Thus, the hierarchically Fe-doped porous carbon material derived from PR material is expected to realize high rate capacitance for supercapacitor applications.

Carbon nanomaterials that are electrochemically bifunctional and active in supercapacitor and hydrogen-evolution-reaction (HER) applications have attracted recent research attention. We have prepared porous carbon spheres - doped Ni, Co - alloys by using a hydrothermal method with melamine and pectin as precursors and with the addition of nickel nitrate and cobalt nitrate. The corresponding materials exhibit good electrochemical performance and excellent electrocatalytic activity for HER. The overpotential (OP) of the as-prepared materials can achieve 240 mV keeping a Tafel slope (TS) of 55 mV dec−1 at 10 mA cm−2 in an acid (0.5 M H2SO4) solution. The corresponding samples maintain stability after 24 h and 5000 cycles in the chronovoltage and cyclic voltammetry methods, respectively. When the as-prepared materials are oxidized by 30% H2O2 for 12 h, the corresponding as-prepared oxidation samples exhibit excellent electrochemical performance in a supercapacitor application. The specific capacitance (SC) of the as-obtained materials reaches 312 F g−1 at 1 A g−1 with decent rate capability and cyclic stability. This work provides new applications for bifunctional electrochemically active materials.

Carbon nanotubes (CNT) are potential electrode materials for supercapacitors due to their high specific surface area and excellent conductivity. Here, 1,4-Naphthoquinone (NQ)-modified nitrogen-oxygen co-doped carbon nanotubes (NQ/N–O-CNT) were synthesized. The influences of NQ modification on the structure and electrochemical properties of as-prepared materials were examined by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron microscopy (XPS), scanning electron microscopy (SEM), galvanostatic charge/discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). By the modification process, nitrogen and oxygen were effectively doped into CNT, causing an increase in nitrogen- and oxygen-containing functional groups, which was proved by XPS and FTIR. The effective debundling of CNT and the presence of densely packed globular structures on the surface of individual nanotubes was confirmed by SEM. And benefited from the reversible redox reaction of NQ, the specific capacitance of NQ/CNT composites can reach up to 143.68 F g−1, which is 4.5 times higher than that of CNT (25.78 F g−1), demonstrating quinone organic compounds can serve as a sustainable pseudocapacitor material for high-performance supercapacitors. After 3000 cycles, the specific capacitance is still 83.6% of its original value.

Traditional carbon aerogels are made of resorcinol and formaldehyde. The synthesis process is cumbersome and the electrochemical performance is poor. Therefore, designing carbon aerogels with environmentally friendly raw materials, simple synthesis steps and good electrochemical performance is of great important. In this article, Cu-doped carbon aerogels (Cu-CA) were synthesized by one-step carbonization using sodium alginate (SA) as the carbon precursor. The specific surface area of the Cu-CA was 230.4 m2 g−1. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to obtained the microstructure of the Cu-CA. Cu nanoparticles (Cu NPs) were found to be embedded in the carbon aerogels homogeneously. The performances of the Cu-CA as supercapacitor electrode materials were investigated via cyclic voltammetry test (CV), galvanostatic charge-discharge test (GCD) and electrochemical impedance spectroscopy (EIS) using three-electrode system and the reference electrode was Hg/HgO electrode. Due to the metal-doped and unique hierarchical porous structure, the specific capacitance of the Cu-CA was up to 414.4 F g−1 with GCD (scan rate: 0.3 mV s−1), and the Cu-CA electrode showed good cycling stability. The excellent electrochemical performances of the Cu-CA indicate their great potential applications in the energy storage field.

Novel octahedron-like hybrids of highly graphitized carbon dopants and Fe2O3 (C-Fe2O3-2) were prepared via a simple one-pot annealing method. The morphology and level of graphitization of the carbon dopant in the Fe-based materials could be controlled by poly(vinyl pyrrolidone) (PVP). When using C-Fe2O3-2 as the catalyst in the heterogeneous Fenton-like reaction of methylene blue (MB) degradation, 96% of MB was removed within 420 min in the presence of H2O2. Furthermore, the activity of the carbon-doped Fe2O3 remained nearly constant over five cycles, indicating the long-term catalytic durability and recyclability of the catalyst. The large surface area and the synergistic effect between Fe2O3 and the highly graphitized carbon dopant in C-Fe2O3-2 are considered to be responsible for the enhanced Fenton-like performance.

Carbon aerogels with excellent conductive characteristics and high specific capacitance have attracted more and more interests for next-generation energy storage applications. Three-dimensional interconnected Mn2O3/carbon aerogel supercapacitor electrodes are prepared by a novel doping method using MnO2 coordinated by N, N-dimethylmethanamide (DMF). The coordinative MnO2 (DMF/MnO2) plays a key role in the sol-gel process of resorcinol and formaldehyde. The doped carbon aerogels exhibits a high specific surface area of 859 m2 g−1 and a good pore-size distribution of 10–15 nm. All of the doped carbon aerogels exhibit higher specific capacitance than pure carbon aerogels, and the highest specific capacitance (170 F g−1), at current density of 1.0 A g−1, is obtained in Mn–CA–5% when 5 mol% DMF/MnO2 is added to the precursor solution. The specific capacitance is as high as 100 F g−1, at current density of 10.0 A g−1, and 97% of initial capacitance is retained over 1000 cycles at a current density of 5.0 A g−1. The doped carbon aerogels exhibits a high coulombic efficiency (up to 99.8%) and a good rate capability. The corresponding result is due to the novel doping method of DMF/MnO2 addition.

A new ternary poly(e-caprolactone) (PCL)/poly(ethylene oxide) (PEO)@AuNPs composite material with high catalytic activity and favorable structural stability has been successfully prepared. The prepared PCL/PEO composite fibers by electrospinning have been treated with an easy-to-operate solvent vapor annealing (SVA) process, demonstrating wrinkled fiber nanostructures, promoting the significantly high specific surface area and more active sites in the surface of electrospun fiber. Then NaBH4 was used as a reducing agent to reduce HAuCl4 to form gold nanoparticles, resulting in the targeted PCL/PEO@AuNPs composite material. The obtained PCL/PEO@AuNPs composites demonstrated potential catalytic ability and good reusability in the catalytic reduction of 4-nitrophenol and 2-nitroaniline systems, showing promising and wide applications in catalytic composite materials and self-assembled films.

Long non-coding RNAs (lncRNAs) have been increasingly found to fulfill key functions in neurodegenerative diseases. This study aimed to probe the function of lncRNA MALAT1 in neuronal recovery in Alzheimer's disease (AD). Aβ25-35 was used to induce AD in a rat model and neuronal injury in PC12 and C6 cells. Aberrantly expressed lncRNAs/microRNAs (miRNAs) in AD rats were screened out by microarray analyses. Altered expression of MALAT1, miR-30b and CNR1 was performed to explore their roles in neuronal recovery in rat and cell models. Consequently, LncRNA MALAT1 and CNR1 were poorly expressed while miR-30b was highly expressed in Aβ25-35-induced rat models and cells. Overexpression of MALAT1 or CNR1 reduced neuronal injury in rat hippocampus. It increased viability and decreased apoptosis in injured PC12 and C6 cells, and decreased the secretion of pro-inflammatory factor IL-6 and TNF-α but increased IL-10 production. However, overexpression of miR-30b reversed these trends. MALAT1 could served as a sponge for mR-30b to up-regulate CNR1 expression. The phosphorylation of PI3K and AKT was stimulated when MALAT1 or CNR1 was overexpressed. To sum up, we found MALAT1 could promote neuronal recovery following AD through the miR-30b/CNR1 network and the PI3K/AKT signaling activation.

Porous biomass-carbon materials for supercapacitor applications have recently attracted attention. Chitin, which has abundant amides and hydroxyl groups, was used as an ideal precursor for carbon in this work. The chitin was treated with a one-step method to produce a heteroatom-loaded porous carbon material, and its electrochemical properties were significantly improved through the introduction of loaded elements. A mixture of chitin, zinc chloride, and heteroatoms was carbonized to obtain heteroatoms (N and S) and the bimetallic sulfide loaded hierarchical porous carbon. Then, the porous carbon with S, N, Zn, and Fe heteroatoms loading was used to prepare a supercapacitor with a specific capacitance of 277.4 F g−1 at 1 A g−1. In addition, the supercapacitor had a specific capacitance retention rate of 90% at 5 A g−1 after 10,000 cycles. Therefore, hierarchical porous carbon materials loaded with heteroatoms and bimetallic sulfide were prepared by carbonization activation with chitin as the precursor. The resulting supercapacitor showed that the as-prepared porous biomass materials possessed ideal charging-discharging performance. Moreover, this work provides strategies for obtaining metal sulfides and heteroatom co-loading of carbon materials with excellent properties using a simple and efficient one-step method for renewable energy storage device applications.

Porous carbon xerogels were successfully fabricated by carbonization of resorcinol-formaldehyde-phloroglucinol gels in the presence of surfactants. The effect of non-ionic, cationic, anionic and zwitterionic surfactants on the porous structure of carbon xerogels was investigated. Micropore structural carbon xerogels were obtained when a cationic surfactant was used. The result of surface tension test showed the non-ionic surfactant Tween 60 gave the lowest surface tension. Thermal conductivity experiments revealed the carbon xerogels in this work possessed low thermal conductivity and are suitable as thermal insulation materials. The pore size directly determined the thermal conductivity of carbon xerogels, and the thermal conductivity decreased with pore size. Among the obtained samples, the one using hexamethylenetetramine (HTM) exhibited the highest CO2 adsorption capacity (2.89 mmol g−1) and adsorption selectivity as a result of the high microporosity (88.0%). Therefore, HTM-CA was identified as a promising material for CO2 adsorption.

Improving the specific capacitance of carbon aerogels in supercapacitors and maintaining their high specific surface area remained an important challenge. Here, we prepared resorcinol–phloroglucinol–formaldehyde carbon aerogels reduced with hydrazine hydrate by a microwave method. The effects of the amount of hydrazine hydrate and the time of microwave reaction on the electrochemical performance of carbon aerogels were investigated. The reductive carbon aerogels were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The XPS spectra of reductive carbon aerogels indicated a presence of four nitrogen N1s groups, three oxygen O1s groups and six carbon C1s groups in the deconvoluted spectra. Surface area analysis and electrochemical performance were also investigated. The results showed that the specific surface area of the N-doped carbon aerogels could be as high as 803 m2 g−1. According to the electrochemical testing results, the specific capacitance of the N-doped carbon aerogels significantly increased and reached 219 F g−1 at a current density of 1.5 A g−1 compared to the pristine carbon aerogels. The optimal dosage and time of hydrazine hydrate was 20.6 mol L−1 for 25 min. The N-doped carbon aerogels electrode exhibited excellent reversibility with a cycling efficiency of 93.6% after 10000 cycles.

Heteroatom doping in carbon aerogels is critical for improving the surface areas and electronic properties of these aerogels. This paper demonstrates doping sulfur (S) atom into carbon aerogels. S-doped carbon aerogels (S-CAs) were prepared via a sol-gel process using phloroglucinol (P), resorcinol (R) and formaldehyde as the polymerization precursors with sodium carbonate (Na2CO3) as the basic catalyst and sodium 4-hydroxybenzenesulfonate (HBS) as the surfactant. The as-synthesized products were dried in normal temperature and carbonized with temperature-programmed. The effects of S-doping on the surface area and electronic properties of the S-CAs were studied by a surface area analyzer and electrochemical workstation. When the S loading was up to 1.38%, the corresponding S-CA exhibited the most optimal surface area and specific capacitance. The textural properties were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), a surface area analyzer, an X-ray diffraction spectrometer, a Raman spectrometer, the X-ray photoelectron spectroscopy (XPS) spectra, an elemental analyzer and an EDX detector, and the electrochemical properties were measured using cyclic voltammetry, galvanostatic charge–discharge measurements and electrochemical impedance spectroscopy (EIS). When the molar ratio of HBS/(P + R) was 0.05, the S loading was 1.38%, the specific surface area of the as-synthesized CA was 831 m2/g, and its specific capacitance was 105 F/g.

A novel, carbon-doped graphitic carbon nitride (C C3N4-20) was used for methylene blue (MB) removal from an aqueous solution. In dye adsorption experiments, C C3N4-20 showed a high MB adsorption efficiency due to its extended π-conjugation system and porous structure, the maximum adsorption capacity of C C3N4-20 for MB was 57.87 mg g−1, when the initial concentrations of MB were 20 mg L−1. A Langmuir model fit the MB adsorption isotherm of C C3N4-20, and a pseudo-second-order kinetic model fit the adsorption kinetics. The MB adsorption process on C C3N4-20 is physical and mainly via electrostatic attraction and π–π interactions.

MicroRNA (miR)-34a was recently determined to contribute to the pathological development of Alzheimer's disease (AD). miR-34a deficiency significantly attenuates cognitive deficits in amyloid precursor protein (APP)/presenilin 1 (PS1) mice; however, its role in early AD pathology and the underlying mechanisms remain elusive. Here, we confirmed that the increase of miR-34a expression in APP/PS1 mice was earlier than the relevant AD pathological characteristics, such as amyloid-β production, amyloid plaque deposition, and cognitive deficits. Furthermore, because predicted miR-34a target genes were broadly linked to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and N-methyl-d-aspartate (NMDA) receptors, we evaluated synaptic plasticity by investigating high-frequency conditioning tetanus-induced excitatory postsynaptic potential, which revealed that synaptic plasticity was promoted in miR-34a knockout/APP/PS1 mice. Therefore, we assessed the expression of the presynaptic components synaptophysin and postsynaptic density protein 95 (PSD95) and found that synaptophysin and PSD95 were not altered by miR-34a deficiency. Additionally, the synaptic strength (vesicular fusion, vesicular docking, and transporting) was either not significantly changed. We also evaluated the levels of AMPA and NMDA receptors, which showed that the expression of AMPA and NMDA receptors was markedly upregulated in APP/PS1 mice with miR-34a deficiency. We conclude that miR-34a is involved in synaptic deficits in AD pathological development, which was, at least in part, due to the inhibition of NMDA (by miR-34a-5p) and AMPA (by miR-34a-3p) receptor expression.

Ternary carbon aerogels (CAs) were fabricated via a sol–gel process using resorcinol–formaldehyde (R–F), hydroxyethyl cellulose (HC) and carbon fibers (CFs) in the presence of an acid–base catalyst. The acid–base catalyst was composed of ascorbic acid (VC) and sodium carbonate. The products were carbonized at 900 °C in a nitrogen atmosphere. The effects of the acid–base catalyst on the structure and the electrochemical properties of the resulting CAs were studied. The textural and electrochemical properties were investigated by variable instruments (e.g. scanning electron microscopy (SEM), transmission electron microscopy (TEM), an ASAP 2420 surface-area analyzer, and a GAMRY Interface 1000 electrochemical workstation). These tests showed that, when the molar ratios of F/R, VC/R and Na2CO3/R were 2, 0.02 and 0.002, respectively, and the mass ratios of HC/R and CF/R were 0.09 and 0.005, respectively, the specific surface area of the resulting CA was 1071 m2 g−1 and its specific capacitance was 131 F g−1; both of these values are substantially better than those in prior reports.

The influence of metals on the structure and performance of carbon aerogels is presented here. Metal-doped carbon aerogels (M-CA) were obtained by a simple in situ method without any catalyst. The physical properties were characterized by SEM, XRD, Raman spectroscopy, XPS, and N2 adsorption-desorption. The results show that the addition of metal particles did not destroy the original 3D structure of carbon aerogels, and Ni-CA displayed excellent pore size distribution and a high degree of graphitization. The results of the electrochemical performance revealed nickel doped carbon aerogel (Ni-CA) gave the highest specific capacitance (126.6 F g− 1) at 1 A g− 1 because of the suitable pore size distribution and high conductivity. A cycling performance test showed good cycle stability of all the M-CA in this study, and the attenuation of Ni-CA after 1000 cycles was the lowest recorded, at only 0.6%.

Electrocatalytic water splitting for hydrogen production is highly desirable to replace oil energy. The catalytic performance is closely related to the conductivity, active sites and reaction Gibbs free energy of the catalyst. A general guideline for improving catalytic performance is to obtain porous carbon-based materials with a high surface area, plentiful defects and metal compound loading. Here, defect-rich nitrogen-doped reduced graphene oxide (RGO) with molybdenum (Mo)-based compound loading was designed through a two-step method. The peroxide-assisted step under low-temperature carbonization with an air atmosphere promotes the formation of defects, and the hydrothermal process improves the crosslinking degree to form a porous structure at a high carbonization temperature. The obtained catalysts exhibit excellent and durable electrocatalytic performance over a broad pH range. In addition, the transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) results clearly reveal the presence of defects. The theoretical analysis demonstrates that the RGO and Mo-based compounds have an efficient synergetic effect on the catalytic activity. This work provides clues for the development of new catalysts for water splitting to produce hydrogen.

Carbon aerogels (CA) with uniform pore structures were prepared by the polycondensation of phloroglucinol, resorcinol, and formaldehyde, using carboxylated chitosan as a soft template. The CA were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and surface area analysis. When carboxylated chitosan was added, the time for wet gel formation was reduced by 60%, and the CA showed a more uniform pore structures. The electrochemical performance of the CA was measured in a three-electrode electrochemical cell. The CA prepared with added carboxylated chitosan showed lower charge transfer resistance on the electrode surface, and the specific capacitances were also enhanced, showing a specific capacitance as high as 135 F/g at a resorcinol-to-carboxylated chitosan mass ratio of 250:1 at a current density of 0.5 A/g. This specific capacitance is much higher than that of the CA without carboxylated chitosan. The capacitance retention under increasing discharge current density was also enhanced by the addition of carboxylated chitosan. The electrochemical performance of the CA in different electrolytes (1 M LiOH, 1 M NaOH, 1 M KOH, 3 M KOH, 6 M KOH, and 9 M KOH) was investigated. The results show that the electrochemical performance in 6 M KOH was better than those in other electrolytes.

In this study, a 3D Fe-based and N-doped coral-like carbon composite (Fe-NGLC) was successfully prepared via the simple impregnation of a self-made 3D nitrogen-enriched and porous layered graphene-like support with Fe2(SO4)3 as the precursor. It was characterized through X-ray diffractometry, scanning electron microscopy, X-ray photoelectron spectroscopy, etc.; Fe-NGLC exhibited regular three-dimensional coral-like structures with dense porosity and high of Fe–N species content. As a heterogeneous Fenton catalyst of the methylene blue (MB) degradation, the prepared composite showed impressive activity over a wide pH range (4–10). Almost 100% of the MB could be degraded in 60 min, and the results agreed well with the pseudo-first-order kinetic model. To identify the crucial active sites of MB degradation, the correlation between the rate constant derived from the pseudo-first-order kinetic model and the different Fe species in the catalyst prepared under various conditions was investigated. This revealed the key role of the Fe–N complexes for the heterogeneous Fenton reaction. Moreover, Fe-NGLC exhibited recyclability and only a slight decrease in removal efficiency after five cycles. The excellent performance of Fe-NGLC demonstrates its great potential as a Fenton catalyst for wastewater treatment.

The preparation method of porous carbon traditionally involves many steps and requires inert atmosphere resulting in time-consuming and high-cost. We reported a simple and easy method of N-doped micro/meso porous carbon (NPC) via a one-step carbonization of polyvinylpyrrolidone, melamine and ammonium chloride in air. The influences of PVP mass and carbonization temperature on surface group function, the morphology, microstructure and pore distribution of NPC samples were studied by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy and surface area analysis. The thermal behavior of NPC was analyzed by thermogravimetric analysis coupled to Fourier transform infrared spectroscopy. Moreover, the electrochemical performances of the as-prepared NPC samples were measured by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The micro/meso pores and high content of pyridine-N and quaternary-N endowed NPC samples with high capacitive performance and long cyclic life. The specific capacitance of the prepared NPC sample could reach as high as 215.9 F g−1 at 1 A g−1 and 89.5 F g−1 even at 10 A g−1. Especially, the symmetric supercapacitor assembled by NPC-3-900 achieved 13.2 W h kg−1 at 350 W kg−1 and excellent cyclic performance (91.4% after 10,000 GCD circles).

Due to high specific surface and plentiful of porosity, 3D porous carbon matrix has shown enormous potential for catalyst supporters. Hydrogen was thought as the next-generation clean energy to substitute the fossil fuel. Metal phosphides has been investigated and exhibited a good catalytic performance for hydrogen evolution reaction (HER). In this work, we prepared Ni2P/CoP loading on Porous carbon matrix through a facile method. The mixture of nickel nitrate, cobalt nitrate and chitosan was ball-milled, then was carbonized under N2 atmosphere at 900°C with NH4HPO2. The as-obtained materials were characterized by X-Ray diffraction (XRD), SEM and Raman spectrums. Also the electrochemical performance for HER was test using electrochemical workstation. The result shown that this catalysts presented a low overpotential at 10 mA cm-2, which was 270 mV.

Carbon aerogels with low cost and eco-friendly are considered as ideal electrode materials for supercapacitors. In this investigation, nitrogen self-doped carbon aerogels (NSCA) are prepared by microwave hydrothermal and high-temperature carbonization using chitin as carbon and nitrogen sources. Zinc chloride is used as a dehydration agent and an activator. Owing to the low boiling point of Zinc chloride, it does not require any additional steps to remove the activator. Also, due to the activation of Zinc chloride, the specific surface area of NSCA reaches 2540 m2 g−1. In the three-electrode system, NSCA-1000 exhibits specific capacitance of 249.4 and 164.9 F g−1 at current densities of 1.0 and 10 A g−1, respectively. In the two-electrode system, the NSCA-1000 based symmetrical supercapacitor demonstrates an energy density and power density of 26.15 Wh kg−1 and 0.95 kW kg−1 at 1.0 A g−1, respectively. Meanwhile, NSCA-1000 displays excellent cycling stability that the specific capacitance can maintain 98.44% after 15,000 cycles at a current density of 2.0 A g−1.

Given its clean energy and absence of exhaust gases, hydrogen is an ideal candidate for energy demand. Electrochemical hydrogen evolution reaction (HER) have attracted increasing attention, and non-precious metal compounds have been considered as next-generation catalysts to replace the traditional Pt-based catalysts in this reaction. This study adopts a novel sol-gel method of chitosan and formaldehyde to prepare an N-doped carbon matrix with Nickel phosphide (Ni2P) and Molybdenum phosphide (MoP) loading. Phytic acid is used as the P source to dissolve chitosan. The interface between Ni2P and MoP in the as-prepared catalysts facilitates HER with an excellent stability in a wide pH universal solution. The onset potentials of the catalyst are 300, 200, and 5 mV in 0.5 mol L−1 sulfuric acid, 1.0 mol L−1 phosphate buffer solution, and 1.0 mol L−1 potassium hydroxide, respectively, and the corresponding Tafel slopes are 63, 99, and 64 mV dec−1. Density functional theory is adopted to support the experiment. Results suggest that the synergistic effect from the interface can obviously reduce the hydrogen adsorption free energy to benefit the adsorption/desorption.

Wet gels (WGs) have been obtained from the polymerization of phloroglucinol (P), resorcinol (R) and formaldehyde (F) using sodium carbonate (C) as catalyst with kaolin (KL) addition. Carbon aerogels (CAs) have been gotten through the carbonization of WGs. The porous texture properties of as - prepared samples are investigated using the surface-area analyzer. The crystal structure of CAs are studied by X-ray diffraction (XRD) and the degree of graphitization are obtained through a Raman spectrometer. Meanwhile scanning electron microscopy (SEM) are executed to observe the morphology of different samples. When the addition of 5 wt%, the samples exhibit the high specific surface area (SSA), up to 855m2 g–1, with a concentrated pore size disdribution (PSD) of 30 nm.

Electrochemical hydrogen evolution has become a popular way to produce clean energy. Traditional catalysts (e.g. platinum (Pt)) are very expensive and rare; therefore, environmentally friendly and cost-effective catalysts are being widely developed. Here, molybdenum carbide and metallic nickel supported on a N-doped porous carbon matrix are prepared as an electrocatalyst through a one-step hydrothermal method with the addition of melamine, polyvinylpyrrolidone (PVP), pectin, ammonium molybdate and nickel nitrate, and the catalysts exhibit excellent catalytic performance for electrochemical hydrogen evolution. The catalysts created with a carbonization temperature of 1000 °C display a low onset overpotential of 60 mV in an acidic solution with a small Tafel slope of 64 mV dec−1 and low overpotentials of 170 mV and 220 mV in 0.5 M H2SO4 and 1.0 M KOH, respectively, at 10 mA cm−2. The obtained catalyst maintains remarkable stability after a 240 h durability test and 10000 cyclic voltammetry cycles. The obtained materials possess excellent catalytic performance for the HER due to the synergistic effect of nickel incorporation into molybdenum carbide and the benefit of the porous N-doped carbon matrix for electron and H∗ transport.

In this article, Fe-doped carbon aerogels were prepared by one-step carbonization using sodium alginate as the raw material. The composition of the materials was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results show that when the carbonization temperature is lower than 700 °C, iron mainly exists in the form of Fe3O4. When the carbonization temperature is higher than 700 °C, iron mainly exists in the form of Fe and CFe15.1.

Microporous carbon xerogels (CXs) were successfully fabricated via a facile one-pot strategy using eutectic salt mixture (KCl and ZnCl2) as dual activator and catalyst. Their pore structures, morphology, and selective CO2 adsorption behaviors were thoroughly studied by varying the contents of eutectic salt mixture. The presented CXs herein showed excellent CO2 adsorption selectivities, and the CX-4 with optimum salt concentration (12.9%) exhibited the highest CO2 adsorption capacity of 4.39 mmol g−1 at 273 K, which was ascribed to their special microscopic pore structure. Compared with the reported carbon materials, the optimum CX-4 exhibits a comparable or superior CO2 adsorption performance under similar conditions, showing great potential for efficient CO2 capture and separation from flue gas and natural gas.

The degradation characteristics of MOCVD grown InGaAsP/InGaAs dual junction solar cells, irradiated by 1 MeV electron, 3 MeV and 10 MeV proton, have been investigated. Main electrical and optical properties of solar cell degraded seriously with the increase of irradiation fluences due to the irradiation induced defects which are acting as non-radiative recombination centers in the active layers of the solar cell. The remaining factor of P m a x is 0.67, 0.53 and 0.51 for 1 MeV electron, 10 MeV proton, and 3 MeV proton irradiation, respectively, when the displacement damage dose (DDD) is 3 . 16 × 1 0 10 MeV/g. The degradation of external quantum efficiency (EQE) of each subcell mainly occurred in the long wavelength region, the integrated current density J s c of InGaAsP and InGaAs subcells degraded more seriously upon 3 MeV and 10 MeV proton irradiation comparing to 1 MeV electron irradiation. The InGaAsP subcell turned out to be the current limiting unit due to the lower J s c before and post irradiation. By applying equivalent displacement damage dose model, the relative damage coefficient for 3 MeV proton to 10 MeV proton and 1 MeV electron to 10 MeV proton have been calculated.

Carbon aerogels with excellent conductive characteristics and high specific capacitance have attracted more and more interests for next-generation energy storage applications. Three-dimensional interconnected Mn

Carbon aerogels of an inter-connected three-dimensional (3D) structure are a potential carbon material for supercapacitors. We report a new oxidation modification method to prepare a series of modified carbon aerogels (OM-CA) by Hummers oxidation method. Oxidation-modified carbon aerogels (OM-CA) are obtained from carbon aerogel powders oxidized by Hummers method. Sulfuric acid stoichiometry is studied in order to investigate the effect of the surface oxygen group on surface area and electrochemical performance. Additionally, heteroatoms are doped into carbon aerogels in the oxidation process. The effect of heteroatom doping on electrochemical performance as a supercapacitor electrode material is investigated. When the amount of sulfuric acid is 40 wt%, the dopping manganese content is 0.9 mol%, the specific surface area of OM-CA is 450 m2/g, and its specific capacitance is 151 F g−1 at 0.5 A g−1, which is achieved by heteroatom doping and texture properties. In addition, OM-CA composite supercapacitors exhibit a stable cycle life at a current density of 0.5 A g−1 and retain 98.0% of initial capacitance over 500 cycles, and OM-CA-40% still presents a higher capacity, up to 148 F g−1 at 0.5 A g−1. The high specific surface area and specific capacitance suggest the porous carbon material has potential applications in supercapacitors.

An N-doped carbon/CuO-Fe2O3 (NC-CuFe) nanocomposite was successfully prepared via a simple, green one-pot annealing method. Different techniques were employed to characterize the physical and chemical properties of the prepared products, such as the composition, texture, structure and reducibility. XRD, XPS, TPR and especially TEM demonstrated the formation of CuFe2O4 in the Cu-doped composite. All the Cu-doped materials (NC-CuFe) showed higher activity in the Fenton reaction of MB degradation than the non-doped sample (C-Fe). In particular, the composite doped with 10 wt% CuO (NC-CuFe-2) exhibited the best performance, with approximately 98% of the methylene blue (MB) removed in 180 min in the presence of H2O2. The high specific surface area, the mutual charge interaction between Cu2+ and Fe3+, the mobility of the lattice oxygen and the high pyridinic N content in NC-CuFe-2 were responsible for the high activity in the Fenton reaction. Moreover, NC-CuFe-2 also demonstrated excellent stability and reusability, which were crucial for practical applications.

We prepared a series of modified carbon aerogels with oxygen-containing functional groups through a sol–gel process by polycondensation of phloroglucinol, resorcinol and formaldehyde using starch addition. The effect of starch addition on the pore structure and electrochemical performance of the carbon aerogels was investigated. Carbon aerogels were characterized by scanning-electron microscopy, transmission-electron microscopy, surface-area analysis, X-ray diffractometry, Raman spectrometry and X-ray photoelectron spectroscopy. The electrochemical properties were studied by using cyclic voltammetry, galvanostatic charge–discharge measurements and electrochemical impedance spectroscopy. When the starch addition was 25 wt%, the as-prepared sample had a specific surface area of 734 m2 g−1 and an outstanding specific capacitance of 147 F g−1 at 1.0 A g−1. The as-prepared carbon aerogels exhibited a high coulombic efficiency and a stable cycle life at a current density of 1.0 A g−1 over 1000 cycles. This ideal performance was attributed to the addition of starch, which was beneficial for the application of carbon aerogels in supercapacitors.

Carbon aerogels were prepared through a polycondensation of phloroglucinol, resorcinol and formaldehyde with sodium carbonate as the catalyst under different drying methods. The drying methods were room temperature drying, vacuum drying and freeze drying. The effects of different drying methods on the porous structure of carbon aerogels were studied systematically. The texture and pore structure were investigated under scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and a surface-area analyzer. The results show that the freeze-drying method was good for the specific surface area of carbon aerogels, up to 843 m2 g–1.

A detailed study on electrical and optical inhomogeneity in N-face GaN grown by hydride vapor phase epitaxy is presented. There are two distinctive regions with non-homogeneous electrical and optical properties in N-face of GaN revealed by wet etching, Raman and cathodoluminescence. One region exclusively exhibited stronger donor–acceptor pair emission and higher carrier concentration due to impurity incorporation. A strong red-shift of near band edge emission of ∼24 meV was also observed owing to additional carrier concentration. Furthermore, the activation energy difference of the etching process between the two regions is ∼0.12 eV. The distinctive etching topography was probably due to the difference of surface potentials related to the level of carrier concentration in GaN.