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Amphiphile-assisted silica@graphite with a surface resistivity of 1012 Ω·sq−1 was prepared via a one-step process using either an Ostwald ripening agent (Triton-X) or a bridgemer (PEG) under mild conditions. The composites containing coated fillers showed advantages in terms of their thermal and electrical properties over those using mixture of fillers. The filler possessing optimal size of graphite was incorporated with various polymer matrices such as TPEE, PDMS, epoxy, or HDPE, all of which have different processing characteristics due to their inherent viscosities. Consequently, the silica@graphite incorporated composites were found to have a superior effect on thermal and electrical properties including conductivity, dissipation, stability, and resistivity than boron nitride or alumina filled composites with the conservation of the electrical insulating property above 1010 Ω·sq−1 for a filler loading of 0–30 vol%.

Boron nitride (BN) particles were treated with atmospheric-pressure radio frequency plasma and then modified using a triethoxyvinyl silane coupling agent in order to enhance the thermal conductivity of polydimethylsiloxane (PDMS) composites. Raw BN, silane-treated BN, and silane-plasma-treated BN were incorporated into PDMS matrix. The surface modification by plasma and coupling agent was verified. The composites filled with treated BN showed a superior effect on thermal conductivity compared to the raw BN filled composite at the same filler loading. Specifically, using silane-plasma-treated BN at 40 wt% of BN increased the thermal conductivity from 1.7 to 3.4 W/mK.

Designing air-stable perovskite solar cells (PSCs) is a recent trend in low-cost photovoltaic technology. Metal oxide-based electron transporting layers (ETLs) and hole transporting layers (HTLs) have attracted tremendous attention in PSCs, because of their excellent air stability, high electron mobility, and optical transparency. Herein, we report a co-precipitation method for the synthesis of p-type nanoporous nickel oxide (np-NiOx) thin films as the HTL for inverted (p-i-n) PSCs. The best-performing p-i-n PSC having np-NiOx HTL, (FAPbI3)0.85(MAPbBr3)0.15 (herein FAPbI3 stands for formamidinium lead iodide and MAPbBr3 stands for methylammonium lead bromide) perovskite and phenyl-C61-butyric acid methyl ester (PCBM)/ZnO ETL exhibited a 19.10% (±1%) power conversion efficiency (PCE) with a current density (JSC) of 22.76 mA cm−2, open circuit voltage (VOC) of 1.076 V and fill factor (FF) of 0.78 under 1 sun (100 mW cm−2). Interestingly, the developed p-i-n PSCs based on p-type NiOx and n-type ZnO could retain >80% efficiency after 160 days, which is much higher than conventional PEDOT:PSS HTL-based PSCs. Our findings provide air-stable perovskite solar cells with high efficiency.

In rechargeable lithium-oxygen (Li-O2) batteries, the porosity of porous carbon materials plays a crucial role in the electrochemical performance serving as oxygen diffusion path and Li ion transfer passage. However, the influence of optimization of porous carbon as an air electrode on cell electrochemical performance remains unclear. To understand the role of carbon porosity in Li-O2 batteries, carbon materials featuring controlled pore sizes and porosity, including C-800 (nearly 96% microporous) and AC-950 (55:45 micro/meso porosity), are designed and synthesized by carbonization using a triazine-based covalent organic polymer (TCOP). We find that the microporous C-800 cathode allows 120 cycles with a limited capacity of 1000 mAh g−1, about 2 and 10 times higher than that of mixed-porosity AC-950 and mesoporous CMK-3, respectively. Meanwhile, the specific discharge capacity of the C-800 electrode at 200 mA g−1 is 6003 mAh g−1, which is lower than that of the 8433 and 9960 mAh g−1 when using AC-950 and CMK-3, respectively. This difference in the electrochemical performance of the porous carbon cathode with different porosity causes to the generation and decomposition of Li2O2 during the charge and discharge cycle, which affects oxygen diffusion and Li ion transfer.

본 연구에는 무기계 내화 필러와 팽창재료를 충전한 실리콘 고무 복합체의 내화 성능과 열적 안정성 및 기계적 강도를 분석하였다. 가스 토치 화염시험과 열 중량분석(TGA)을 통해 미네랄 섬유(mineral fiber)/실리콘 고무 복합체는 규회석(wollastonite)/실리콘 고무 복합체와 운모(mica)/실리콘 고무 복합체보다 내화 성능이 우수하다는 것을 확인하였다. 주사전자현미경(SEM)을 통해 규회석은 실리콘 고무에 분산성이 양호함을 확인하였고, 만능재료분석기(UTM)를 통해 분석한 결과 기계적 강도가 가장 우수했다. 팽창재료(팽창흑연 및 팽창질석) 2종은 가스 토치 화염시험 결과 내화 필러/실리콘 고무 복합체의 내화성능을 보다 향상시킬 수 있다는 것을 확인하였다. 특히, 팽창흑연이 충전된 실리콘 고무 복합체가 팽창질석이 충전된 실리콘 고무 복합체보다 내화성능이 더 우수함을 확인하였다. 하지만, 기계적 특성의 경우, 팽창질석이 충전된 실리콘 고무 복합체가 팽창흑연이 충전된 실리콘 고무 복합체보다 다소 우수하였다.

A carbonate-containing conversion film was fabricated on the surface of AZ31 magnesium alloy to enhance its corrosion resistance by immersion in a CO2 saturated NaOH solution by varying the immersion times (0, 1, 10, 30, and 60 min). Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were utilized to investigate the morphology, crystallinity, and composition of the surface, respectively. The corrosion resistance was tested using a 5 wt% NaCl solution and electrochemical analysis was conducted to confirm the influence of the immersion time on the corrosion resistances of AZ31 alloys. The composition of formed film consisting of a magnesium complex was strongly influenced by the immersion time, where the carbonate and aluminum contents on the surface of the samples increased after the immersion treatment. The AZ31 alloy immersed in NaOH for 10 min possessed a suitable conversion coating film with a magnesium complex, consequently leading to the best corrosion resistance.

Herein, oxygen-deficient Fe-doped Co3O4 polyhedral nanoparticles derived from FeCo‐based bimetal–organic frameworks are prepared for the electrocatalytic oxygen evolution reaction (OER) via a facile self‐templating strategy. A well-defined rhombic dodecahedral structure with abundant oxygen vacancies was constructed based on the coprecipitation, carbonization, oxidation, and partial reduction process. The proposed synthetic method is effective for fabricating a bimetallic hierarchical structure with a rough surface and a moderately controlled electronic structure, which significantly facilitates charge and mass transfer and appropriately exposes the active sites for efficient electrocatalysis. Subsequently, the as-obtained defect-rich Fe-doped Co3O4 nanoparticles was found to be a superior OER electrocatalyst, with a small overpotential of 318 mV required for a current density of 10 mA cm−2, a low Tafel slope of 76.8 mV dec−1, a turnover frequency of 0.1553 s−1 at an overpotential of 370 mV, and outstanding long-term durability in 1.0 M KOH. The proposed strategy will offer a new approach in the design and development of electrochemically active non-noble materials as advanced catalysts for various energy storage and conversion applications.

In this work, one-step phosphosulfurization is demonstrated to prepare P-doped nickel cobalt sulfide nanoneedles vertically decorated on nickel foam (P-NiCo2S4/NF) as an extremely efficient electrocatalyst toward the oxygen evolution reaction (OER). The phosphosulfurization is conducted on nickel cobalt carbonate hydroxide in the presence of P2S5. The P-NiCo2S4 nanoneedles on the nickel foam generate a synergistic effect that provides effective mass and electron transfer pathways, endows the electrocatalyst with a moderate electronic structure, and facilitates gas diffusion to enhance the electrocatalytic performance. The catalysts yield a small overpotential of 300 mV to reach a current density of 50 mA cm−2, Tafel slope as low as 70 mV dec−1, and long-term stability over 100 h. These findings highlight the practical feasibility of P-doped NiCo2S4 on NF for water splitting and offer a new approach for efficiently preparing advanced electrocatalysts in the future.

Herein, 3D in-situ hollow carbon fiber/carbon nanosheet/Fe3C@Fe3O4 (h-CNF/CNS/Fe3C@Fe3O4) was constructed using ferrocene and oleic acid by a solventless one-step process that did not require additional filtering, neutralization, drying, or calcination steps. The iron-oleate chelating structure that self-assembled during annealing facilitated the fabrication of 3D in-situ h-CNF/CNS/Fe3C@Fe3O4 by undergoing graphitization at 600 °C. This carbon shell of the 3D in-situ h-CNF/CNS/Fe3C@Fe3O4 was derived from the two cyclopentadienyl rings in ferrocene. This hybrid material made from economically cheap oleic acid exhibited superior supercapacitive behavior: high specific capacitance of 327 F g−1 at 5 mV s−1 and 210 F g−1 at 10 mV s−1, good rate capability of 60 F g−1 at 10 A g−1 (compared to 70 F g−1 at 1 A g−1 for pure Fe3O4), and superior retention of 108% after 6000 cycles at 100 mV s−1. These superior supercapacitive properties were ascribed to the 3D graphitic h-CNF/CNS for enhancing electrical conductivity and the carbonaceous shell over Fe3C@Fe3O4 core for buffering the bulk expansion of iron-related particles.

실란 커플링제 도입에 따라 silica가 충전된 폴리프로필렌의 기계적, 열적 물성에 미치는 영향을 살펴보았다. Epoxy, amino와 methacryloxy 작용기를 가지고 있는 실란 커플링제를 사용하였다. 종류, 농도와 실란 커플링제의 처리방법에 따라 silica/PP 복합체의 인장강도, 굴곡강도, 충격강도 및 열적안정성을 분석하였다. 용융혼합 및 압축성형에 의해 제조된 복합재료 샘플의 기계적 특성을 조사하기 위해 만능재료시험기와 충격시험기를 사용하였고, 열적특성을 조사하기 위해, TGA와 DSC를 사용하였다. 건식방법으로 amino 작용기를 가지고 있는 실란 커플링제를 5 wt% 혼합한 silica/PP 복합체가 기계적 물성과 열적 물성이 가장 우수한 것으로 확인되었다.

The conventional unstable and expensive hole transporting materials (HTM) has been replaced by cost effective modified carbon hole extraction layer. Herein, we demonstrated a new recipe toward air stable and waterproof modified carbon hole extraction layer for efficient perovskite solar cells (PSCs). The commercial available carbon ink modified with methylammonium lead iodide (MAI) has been used as hole extraction layer for ambipolar perovskite solar cells. The fabricated optimized perovskite solar cell having Glass/FTO/mp-TiO 2 /MAPbI 3-x Cl x /carbon + MAI/Carbon configuration exhibited η = 13.87% power conversion efficiency (PCE) with open circuit voltage (V OC ) 0.997 V, current density (J SC ) = 21.41 mAcm −2 and fill factor (FF) 0.65. Furthermore, the air stability were tested at room temperature in open atmosphere. The water proof stability was tested under water flushing. Our results revealed that, although our carbon based devices show lower PCE (η = 13.87%) compared to spiro-MeOTAD HTM (η = 15%), the fabricated PSCs could even retain >90% after water exposure >20 times and ambient air stability more than 160 days. Further the large area device (>1 cm 2 ) device shows 13.04% PCE with Jsc = 21.47 mAcm −2 , V OC = 0.996 V and FF = 0.61. We have also demonstrated >13% efficiency for large area device (>1.1 cm 2 ), demonstrating that the developed method is simple, cost effective and promising towards large area device fabrication. The developed methodology based on low cost carbon hole extraction layer will be helpful towards waterproof and air stable perovskite solar cells for large-area devices.

A promising supercapacitor material based on chitosan-modified graphene/polyaniline (CS-G/PANI) composite has been successfully synthesized by in situ polymerization. In this work, we established an environmentally friendly approach to the synthesis of well-dispersed graphene based on the biodegradable polymer chitosan (CS) using graphene oxide (GO) as a precursor. The merit of this approach is that CS acts as a stabilizing agent for GO after reduction. The resulting material was shown to exhibit good dispersion in water, and hence, this CS-G facilitates the adsorption of aniline monomers by increasing the exposure of aniline nuclei growth sites. Under the same polyaniline (PANI) concentration, chitosan modified graphene/PANI (CS-G/PANI) nanocomposites showed higher PANI adsorption than graphene/PANI (G/PANI). The CS-G/PANI nanocomposite achieved a greater which is the highest value reported to date for starch-modified graphene subjected to in situ polymerization. The modified CS-G/PANI electrode shows a potential alternative path to achieve high capacitance by preventing graphene aggregation in a simple and cost effective method, which consequently leads to a new avenue for fabricating excellent electrochemical devices.

Aligned carbon nanofibers (ACNFs) were fabricated by electrospinning using a high speed of rotary collector (2000 rpm). To achieve a synergy effect of the electron double layer and redox faradaic reaction, NiCo 2 O 4 was deposited on the surface of the ACNFs using an electrodeposition method. The improved electrochemical performance of the electrodes was investigated by cyclic voltammetry, galvanostatic charge-discharge testing, and electrochemical impedance analysis. Among the prepared electrodes, which were deposited for different times (5, 10, 20, and 30 s), the sample deposited by NiCo 2 O 4 for 10 s had the highest specific capacitance (90.1 F g −1 at 5 mV s −1 ), good rate capability (64.7%), and cycle stability (85.2% after 1000 cycles). In addition, to examine the effects of the alignment and redox faradaic reaction of NiCo 2 O 4, the ACNFs covered with NiCo 2 O 4 for 10 s (NC-ACNFs) were compared with the ACNFs deposited by Co 3 O 4 (C-ACNFs) and randomly oriented carbon nanofibers covered with NiCo 2 O 4 (NC-RCNFs) . The NC-ACNFs had a 15.8% and 11.3% higher specific capacitance than that of the C-ACNFs and NC-RCNFs, respectively. These results suggested that the electrochemical properties of carbon nanofibers could be improved through the structural effects of aligned nanofibers and a redox faradaic reaction of NiCo 2 O 4 .

Ceramic coatings endow carbon materials with electrically insulating properties. For graphite, it is unclear whether ceramic coatings applied via a one-step process under mild conditions can lead to superior coverage. This paper reports that a modified Stober method with an appropriate choice of amphiphiles could yield an electrically insulating coating layer on graphite (d50 3–300 μm, d90 6–550 μm) within 24 h with high reproducibility. A silica coating mechanism involving functional groups on the edge of the graphite, Oswald ripening agents, and a bridgemer was investigated. The mechanism was based on the silica coating morphology, which depends on the amphiphile, and the correlation between coverage and surface resistivity was assessed. Amphiphile-assisted silica@graphite with a surface resistivity of 1012 ohm sq−1 was produced. The thermal conductivity of the silica-coated graphite (amphiphile-assisted silica@graphite)/TPEE composite reached values over 75% higher than that of the raw graphite/TPEE composite with electrically insulating properties.

The development of hybrid organo-lead trihalide perovskite solar cells (PSCs) comprising an electron transporting layer (ETL), a perovskite light absorber and a hole transporting layer (HTL) has received significant attention for their potential in efficient PSCs. However, the preparation of a compact and uniform ETL and the formation of a uniform light absorber layer suffer from a high temperature processing treatment and the formation of unwanted perovskite islands, respectively. A low temperature/room temperature processed ETL is one of the best options for the fabrication of flexible PSCs. In the present work, we report the implementation of a room temperature processed compact TiO2 ETL and the synthesis of extremely uniform flexible planar PSCs based on methylammonium lead mixed halides MAPb(I1−xBrx)3 (x = 0.1) via RF-magnetron sputtering and a toluene dripping treatment, respectively. The compact TiO2 ETLs with different thicknesses (30 to 100 nm) were directly deposited on a flexible PET coated ITO substrate by varying the RF-sputtering time and used for the fabrication of flexible PSCs. The photovoltaic properties revealed that flexible PSC performance is strongly dependent on the TiO2 ETL thickness. The open circuit voltage (VOC) and fill factor (FF) are directly proportional to the TiO2 ETL thickness while the 50 nm thick TiO2 ETL shows the highest current density (JSC) of 20.77 mA cm−2. Our controlled results reveal that the room temperature RF-magnetron sputtered 50 nm-thick TiO2 ETL photoelectrode exhibits a power conversion efficiency (PCE) in excess of 15%. The use of room temperature synthesis of the compact TiO2 ETL by RF magnetron sputtering results in an enhancement of the device performance for cells prepared on flexible substrates. The champion flexible planar PSC based on this architecture exhibited a promising power conversion efficiency as high as 15.88%, featuring a high FF of 0.69 and VOC of 1.108 V with a negligible hysteresis under AM 1.5 G illumination. Furthermore, the mechanical bending stability revealed that the fabricated devices show stable PCE up to 200 bending cycles. The interface properties revealed that the 50 nm thick TiO2 ETL provides superior charge injection characteristics and low internal resistance. The present work provides a simplistic and reliable approach for the fabrication of highly efficient stable flexible perovskite solar cells.

Thermally expandable microspheres were prepared by suspension polymerization using low-temperature initiators. The copolymer shells were made from acrylonitrile (AN) and methyl methacrylate (MMA) as the major monomers. Methacrylonitrile (MAN) was used as the third monomer to improve the expansion performance of the microspheres. This study investigated the influences of the initiator species, polymerization temperature, initiator content, and polymerization pressure on the expansion performance. Stable expandable microcapsules and good thermal characteristics were obtained successfully using 1.5 wt% azobis(4-methoxy-2.4- dimethyl valeronitrile) (V-70) as an initiator at a low temperature of 35 °C and at polymerization pressure of 3 bar. The resulting particle size without destruction and secondary nucleation showed a mean diameter of 30 μm under the optimal conditions. The encapsulated contents of the blowing agent were confirmed by thermogravimetric analysis (TGA) to be 40%.

We investigated the heat transfer behavior of thermally conductive networks with one-dimensional carbon materials to design effective heat transfer pathways for hybrid filler systems of polymer matrix composites. Nano-sized few-walled carbon nanotubes (FWCNTs) and micro-sized mesophase pitch-based carbon fibers (MPCFs) were used as the thermally conductive materials. The bulk density and thermal conductivity of the FWCNT films increased proportionally with the ultrasonication time due to the enhanced dispersibility of the FWCNTs in an ethanol solvent. The ultrasonication-induced densification of the FWCNT films led to the effective formation of filler-to-filler connections, resulting in improved thermal conductivity. The thermal conductivity of the FWCNT-MPCF hybrid films was proportional to the MPCF content (maximum thermal conductivity at an MPCF content of 60 wt %), indicating the synergistic effect on the thermal conductivity enhancement. Moreover, the MPCF-to-MPCF heat transfer pathways in the FWCNT-MPCF hybrid films were the most effective in achieving high thermal conductivity due to the smaller interfacial area and shorter heat transfer pathway of the MPCFs. The FWCNTs could act as thermal bridges between neighboring MPCFs for effective heat transfer. Furthermore, the incorporation of Ag nanoparticles of approximately 300 nm into the FWCNT-MPCF hybrid film dramatically enhanced the thermal conductivity, which was closely related to a decreased thermal interfacial resistance at the intersection points between the materials. Epoxy-based composites loaded with the FWCNTs, MPCFs, FWCNT-MPCF hybrids, and FWCNT-MPCF-Ag hybrid fillers were also fabricated. A similar trend in thermal conductivity was observed in the polymer matrix composite with carbon-based hybrid films.

Porous organic polymers (POPs) with well-distributed and tunable functional groups acting as ligands for specific reactions are promising supports for confining useful novel metals such as Pd, Au, and Pd. Herein, a thiadiazole-containing POP has been successfully synthesized and used for immobilizing Pd species. Pd immobilized inside the micropores (2.3 nm) of the POP material is easily prepared owing to a large amount of the strong anchoring group, thiadiazole, which is intrinsically distributed in the as-prepared POP. The rigid thiadiazole-containing polymer can stabilize the central metal rather than poisoning it. The as-prepared catalyst shows excellent catalytic activity in Suzuki–Miyaura coupling reactions under mild reaction conditions and low catalyst loading. Importantly, the intrinsically distributed thiadiazole ligands can stabilize the Pd moiety, preventing aggregation and leaching, and afford excellent catalytic lifetimes. Consequently, the catalyst can be reused 10 times without a significant loss of its catalytic activity.

Although phosphosulfide and P-doped sulfide materials have been widely reported as highly efficient electrocatalysts for the oxygen evolution reaction (OER), the practical application of these materials is severely hindered by their complicated fabrication method. This paper reports a facile preparation of 3D hierarchical flower-like P-doped Ni–Fe disulfide microspheres by successive hydrothermal and one-step phosphosulfidation, using P2S5 as a source of phosphorus (P) and sulfur (S). Owing to the synergistic effect of the binary metal system, the introduction of P, and unique 3D porous architecture, the flower-like P-doped Ni–Fe disulfide microspheres deliver outstanding OER performance—an overpotential of 264 mV to achieve a current density of 10 mA cm−2, a significantly low Tafel slope of 48 mV dec−1, and excellent long-term durability over 50 h with negligible degradation in alkaline media. The fabrication method applied in this study can provide a new facile approach to the design and synthesis of P-doped metal sulfide materials for various electrochemical applications.

Nylon 6,6/PANI nanofibers using electrospun nylon 6,6 nanofibers as a template are synthesized by the in situ polymerization of different aniline concentrations for the preparation of all-polymer based core-sheath nanofibers with high electrochemical and mechanical properties, such as lightness and flexibility. These nylon 6,6/PANI based sheath nanofibers are used as electrode materials for supercapacitors. The electrochemical performance is examined by cyclic voltammetry (CV), galvanostatic charge/discharge tests and electrochemical impedance spectroscopy (EIS). The galvanostatic charge/discharge test reveals the highest specific capacitance of 665 F g−1 at a current density of 1 A g−1. This electrode also shows remarkable rate charge/discharge capability and high cyclic stability (62% after 1000 cycles). In addition, the high energy density of the nylon 6,6/PANI composite electrode can reach 91 W h kg−1 at a power density of 500 W kg−1. The superior electrochemical properties of the core-sheath nylon 6,6/PANI nanofibers are attributed to their core-sheath structure, thin wall thickness and uniform wall distribution, which can improve the performance of electroactive PANI during the charge/discharge process. The good electrochemical performances highlight the potential of the nylon 6,6/PANI electrode as an electrode material for high-performance supercapacitors.

Manganite (MnOOH) is one of the most effective electrocatalysts for oxygen reduction reaction (ORR), and RuO2 nanoparticles exhibit high activity for oxygen evolution reaction (OER). We herein report a facile means of producing well dispersed RuO2/MnOOH on Ketjen black (RuO2/MnOOH/C) as a bifunctional catalyst for lithium-air (Li-air) batteries. RuO2/MnOOH/C was simply synthesized using a hydrothermal/precipitation based method, and was used as a cathode for a Li-air battery using a Swagelok-type cell. The importance of dispersing active catalysts on a carbon support was clearly demonstrated by textural, charge-discharge voltammetric, and electrochemical impedance spectroscopic (EIS) analyses, comparing results with a catalyst produced by physically mixing RuO2/MnOOH with carbon (RuO2/MnOOH + C). RuO2/MnOOH/C showed low overpotential and stable cycleability up to 170th cycles with 1000 mAh g−1 of charge–discharge capacity, which was attributed to its enhanced active surface area and low charge-transfer resistance. The results obtained suggest that this strategy can be widely applied to bifunctional electrocatalysis, such as secondary batteries and regenerative fuel cell (RFC).

The four different vinyl monomers in the reaction of isocyanate-terminated polyurethane prepolymer were used for the preparation of macromonomers and successfully employed in the dispersion polymerization of styrene. The chemical structures of vinyl monomer in macromonomers influenced on the polystyrene particle characteristics, such as the conversion, weight average molecular weights (Mw), polydispersity index (PDI), weight average diameter (Dw), and uniformity. The conversion of polystyrene increased with amounts of methyl group in vinyl monomer. Also the uniformity of polystyrene particles increased with amounts of methyl group in vinyl monomer.

Oxygen evolution reaction for alkaline water electrolysis was studied using various mixed metal oxide catalysts. Mixed metal oxide electrodes consisting of RuO2, IrO2, and Ta2O5 with various ratios on a titanium substrate were prepared by spray thermal decomposition. The crystallinity of the synthesized catalyst was investigated via X-ray diffraction, and the oxidation state of each component was determined using X-ray photoelectron spectroscopy (XPS). Surface morphology was investigated by scanning electron microscopy, and the roughness factor was determined by cyclic voltammetry (CV) in 1 M H2SO4. Electo-catalytic activity for oxygen evolution reaction was measured by cyclic voltammetry (CV) in 1 M KOH at room temperature, and it was found to be strongly dependent.on composition of catalyst. Among all electrodes tested, catalyst with a composition of Ru:Ir:Ta = 1:2:2.5 exhibited the highest current density of 100 mA cm(-2) at 1.67 V, corresponding to an overpotential of 0.44 V.

Nanostructured manganese oxides were synthesized by a sol-gel method using manganese acetate (MnAc2) and citric acid (C6H8O7,) as precursors, and characterized by Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The nano-rod structure of MnO2 developed gradually when the calcination temperature varied from 380 to 580 degrees C. As the pH increased, the pore size increased, while the specific surface area decreased. The effects of the pH and calcination temperature on the electrochemical properties of the nano-MnO2 electrode, including the supercapacitive behavior, were investigated by cyclic voltammetry (CV) tests. The tests were performed between 0 and 0.8 V versus Ag/AgCl in 1 M Na2SO4 electrolyte at various scan rates (10-200 mVs(-1)). The specific capacitance of the SP-380 sample, prepared at pH 6, was equal to 269.3 Fg(-1). After 300 cycles, approximately a 3.4% increase of the specific capacitance was measured, confirming the excellent cyclability.

Aligned carbon nanofibers (CNFs) were fabricated by electrospinning to evaluate the potential of aligned one-dimensional structure as a supercapacitor electrode. First, randomly oriented polyacrylonitrile (PAN) nanofibers were fabricated, and aligned PAN nanofibers were prepared by increasing the speed of the rotary collector from 250 to 2000 rpm. The prepared PAN nanofibers were carbonized for use as a supercapacitor electrode. According to increase of speed of collector, the specific surface area and electrical conductivity were improved from 533 to 635 m 2 g −1 and from 342 to 626 S cm −1 , respectively. This result might be caused by increased pulling strength between the fibers and the surface of the collector generated by electrospinning as well as the unique aligned nanostructure of CNFs. The specific capacitance and rate capability of the aligned carbon nanofibers (CNFs) were increased by 35.5 and 28.4%, respectively, compared to the randomly oriented CNFs. The enhanced surface area, micropore volume (from 0.19 to 0.24 cm 3 g −1 ), mesopore volume (from 0.08 to 0.26 cm 3 g −1 ), and aligned structure make an impact upon the unique electrochemical properties both low scan rate (10 mV s −1 ) and high scan rate (50 mV s −1 ).

Porous carbon foams were fabricated using phenol and formaldehyde (PF) as carbon precursors. The pore size and porosity of the foams were controlled using glycol-derivatives as porogen during condensation polymerization. The morphology of the resulting carbon foam with macroporous porosity and well dispersed pore structures were verified by mercury porosimetry and scanning electron microscopy. The compressive stress of the resulting carbon foam increased with increasing molecular weights of glycol-derivatives due to the decrease in porosity. Furthermore, the reaction mechanism was identified to involve glycol-derivatives in the condensation reaction of PF, which generated the porosity of the resulting carbon foam by releasing volatile compounds according to thermogravimetric analysis and Fourier transform infrared spectroscopy. As a result, the mechanical properites of the carbon foam could be affected by the morphological properties of macroporous structures using different types and concentrations of glycol-derivatives.

Graphene oxide (GO) was functionalized with a series of amine precursors including ammonia, methylamine, ethylamine, ethylenediamine, dimethylamine, aniline, and 1,4-phenylenediamine (PDA) by a facile solvothermal method for room temperature formaldehyde (HCHO) gas sensing. The as-prepared materials were fabricated via a simple drop-casting method and screened based on the response to 300 ppm HCHO gas at room temperature. GO functionalized with 1,4-phenylenediamine (PDA-GO) was the most sensitive toward 300 ppm HCHO compared to combinations of GO with other amines. The PDA-GO was characterized by transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectrometer, and X-ray photoelectron spectroscopy to investigate the morphology and chemical structure. Remarkably, the response of PDA-GO was almost 24 times higher than that of GO and reached up to 24%. The excellent HCHO sensing properties of the PDA-GO sensor were elucidated by DFT study, which are attributed to the harmony of strong bond formation energy, adsorption energy, and charge transfer during the PDA-GO physically interacting with HCHO. Compared with other reported graphene-based room temperature HCHO gas sensors, PDA-GO exhibits great potential and represents a contribution to the limited studies in the field of organic molecule-functionalized graphene derivatives for HCHO sensor applications.

Fe-doped Ni3S2 nanoneedles supported on nickel foam (NF) are reported as coupled oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) electrocatalysts for effective overall water splitting. The optimized Fe doping density, vertically grown nanoneedle structure without any binder on the conductive substrate, and abundant surface-active sites make the Fe-doped Ni3S2 an efficient catalyst for both electrochemical reactions. The as-synthesized Fe-doped Ni3S2 nanoneedles on NF show an outstanding electrocatalytic performance, only requiring an overpotential of 269 and 314 mV to provide 100 and −100 mA cm−2 for OER and HER, respectively. A water electrolyzer, assembled with the Fe-doped Ni3S2 as both the anode and cathode, displays an exceptionally low onset potential of 1.39 V and achieves a current density of 10 mA cm−2 at a very low cell voltage of 1.58 V with excellent long-term stability for 50 h.

An efficient porous organic polymer (POP)-based adsorbent (4AS-MBP), synthesized from melamine, 4-allyloxy benzaldehyde and ethanedithiol (EDT) via a Schiff-base reaction and thiol–ene addition in a straightforward strategy, was prepared to remove Hg(II) ions from water. The chemical structure and morphology of 4AS-MBP were investigated by FT-IR, solid-state 13C NMR, EA, SEM, TEM and BET analysis. Adsorption experiments were conducted by varying the Hg(II) concentration, contact time and pH to study the adsorption kinetics and equilibrium. Mesoporous 4AS-MBP exhibited a maximum adsorption capacity of 312 mg g−1. The results indicated that Hg(II) adsorbed onto the adsorbent through monolayer chemisorption. Interestingly, 4AS-MBP was highly stable, even in the presence of 2 M NaOH or HCl, and displayed similar adsorption capacities over a wide pH range. Furthermore, the adsorbents could be reused at least five times without a loss of adsorption capacity. More importantly, the relative selectivity coefficients of 4AS-MBP for Hg()/Pb(II), Hg(II)/Cd(II), Hg(II)/Cu(II), Hg(II)/Zn(II) and Hg(II)/Mg(II) were 54.3, 221, 243, 468 and 823, respectively.

Herein, chromium film was successfully synthesized by pulse-reverse (PR) electrodeposition using various anodic current time in a Sargent bath which is mainly composed of hexavalent chromium (Cr6+) and sulfuric acid (H2SO4). The correlation between anodic time during electroplating and various physical properties was investigated. The crack density, hardness, and thickness of electrodeposited chromium was decreased with an increase in anodic time for PR electroplating. The chromium prepared by PR electroplating showed higher corrosion resistance than that prepared by direct current (DC) electroplating owing to low crack density. Consequently, the optimal anodic time for PR electroplating was found to be 0.001 s based on the crack density, hardness, current efficiency, and film thickness. The results obtained suggest that this optimized process is a promising route for electroplating chromium film with low crack density and high corrosion resistance.

【$Mn_{1+X}Co_{2-X}O_4$ solid solutions with various Mn/Co ratios were synthesized by a combustion method, and used as cathode catalysts for lithium/air secondary battery. Their electrochemical and physicochemical properties were investigated. The morphology was examined by transmission electron microscopy (TEM), and the crystallinity was confirmed by X-ray diffraction (XRD) analyses. For the measurement of electrochemical properties, charge and discharge measurements were carried out at a constant current density of $0.2mA/cm^2$ , monitoring the voltage change. Electrochemical impedance spectroscopy (EIS) analyses were also employed to examine the change in charge transfer resistance during charge-discharge process. $Mn_{1+X}Co_{2-X}O_4$ solid solutions showed enhanced cycleability as a cathode of Li/air secondary battery, and the performance was found to be strongly dependent on Mn/Co ratio. Among synthesized catalysts, $Mn_{1.5}Co_{1.5}O_4$ exhibited the best performance and cycleability, due to high charge transfer rate.】

Pt/H-ZSM-5 zeolites (Si/Al ratio of 50) with a Pt loading of 0.28 wt.% were successfully synthesized and employed as catalysts for the selective hydrodealkylation of C 9 + aromatics to benzene, toluene, and xylenes (BTX). Five different crystallite sizes (40, 20, 10, 5, 2 μm) were prepared using different aging times before crystallization. The influence of crystallite size on catalytic activity was investigated, and the catalysts synthesized were physicochemically characterized by XRD, BET, SEM, and ICP-OES. Hydrodealkylation was performed in a conventional fixed bed reactor, and the influences of crystallite size on ethyltoluene (ET) isomer conversion and on the recovery yields of trimethylbenzene (TMB) isomers were examined. Conversion of ET isomers was always higher than that of TMB isomers. The distribution of products obtained was strongly influenced by Pt/H-ZSM-5 crystallite size, that is, ET isomer conversion decreased and TMB isomer recovery yield increased with crystallite size. Catalyst crystallite size was found to dictate catalytic activity with respect to selective hydrodealkylation. Pt/H-ZSM-5 with a crystallite size of 5 μm exhibited the best catalytic performance for the selective hydrodealkylation of C 9 + aromatics to BTX.

Polyurethane modified silicone (PUMS) was synthesized from various molecular weights of polydimethylsi- loxane (PDMS 2000, PDMS 6000, PDMS 20000), polypropyleneglycol with molecular weight of 3000 g/mol (PPG 3000) and 2,4-toluenediisocyanate (TDI) under tin catalyst. Their structures were confirmed by the measurement of FT-IR and 1 H- NMR, and the thermal properties were studied from DSC and TGA. Glass transition temperature of PUMS exhibited exo- thermic peak at �63 ~ �69 o C, and residual weight was 19~35% at 800 o C.

Ball-milled and chemically activated pitch-based carbon fibers (PCF) were prepared for use as electrode materials. Ball milling altered the structure of PCF from fibers to micro-sized particles with loss of porosity. In contrast, chemical activation using KOH facilitated the development of pore structures. The supercapacitive behavior of treated PCF was assessed using cyclic voltammetry and galvanostatic charge/discharge experiments in 6 M KOH electrolytic solution. BAPCF900, the sample subjected to combined ball milling and chemical treatment, activated at 900 °C, exhibited a specific capacitance of about 80 F/g at a current density of 0.2 A/g; this good capacitance is attributed to a specific surface area of 803 m2/g and a total pore volume of 0.352 cm3/g, and is related to the appropriate pore structure for electrode application, comprising mesopores and micropores.

Core-shell thermally expandable microcapsules were prepared via Pickering suspension polymerization. Acrylonitrile (AN) and methyl methacrylate (MMA) were used as the comonomers and the halloysite nanotubes (HNTs) were used as the Pickering emulsifier. The influence of the HNT concentration, AN/MMA ratio, and types of hydrocarbon was investigated. When the HNT concentration was 0.6 wt%, the microcapsules exhibited a core-shell morphology that contained approximately 35 wt% of the blowing agents with an average particle size of 232.0 μm. Increasing the MMA contents resulted in a larger particle size and lower thermal stability. Core-shell microcapsules could be synthesized using iso-hexane, iso-octane, and n-octane, but microcapsules could not be fabricated with n-pentane. At 1 and 3 bar, the contents of the encapsulated blowing agents were 10 %, whereas the contents of the encapsulated blowing agents were approximately 35 and 60 % at 1.5 and 2 bar, respectively.

Multi-walled carbon nanotubes (MWCNTs) were uniformly coated with silica using polyethyleneimine (PEI) as a coupling agent without subjecting the surfaces of the MWCNTs to chemical modification, such as an amine treatment or chemical oxidation. PEI was physically adsorbed onto the MWCNTs, and the silica coating process was performed through a sol-gel reaction of tetraethyl orthosilicate (TEOS) in ethanol under base catalytic conditions at room temperature. PEI was the best coupling agent for coating silica on MWCNTs among the various amphiphilic polymers and surfactant tested, which included Triton X-100, polyvinylpyrrolidone, polyethylene glycol, and sodium dodecyl sulfate. During the sol-gel process using PEI as a coupling agent, silica could be uniformly formed on MWCNTs without any structural defects. As the amount of TEOS used was increased, the thickness of coated silica layer and electrical resistivity of MWCNTs also increased (up to 5.3×1010 Ω sq−1) owing to the high surface coverage of silica on the MWCNTs.

Polyacrylonitrile (PAN) is a favored material for electrospinning and also has been used successfully as a raw material of carbon nanofiber due to its useful and stable structure after treating adequate energy. The PAN nanofibers were prepared and irradiated by electron beam with different dose levels in order to confirm the most efficient dose level on nanofibers. The object of this work is to identify the stabilization of PAN during the irradiation and the effect caused from electron beam irradiation on PAN nanofiber sheets. Upon irradiation, the diameter of nanofibers decreased and the surface area accordingly increased. From structural analyses, that the degree of stabilization increases up to 2000 kGy by disruption C≡N group on PAN. Only short irradiation time less than 1 min can cause the stabilization effect that can be obtained from time-consuming thermal stabilization process.

In this study, in order to improve the thermal and electrical properties of epoxy/graphene nanoplatelets (GNPs), surface modifications of GNPs are conducted using silane coupling agents. Three silane coupling agents, i.e. 2-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane (ETMOS), 3-glycidoxypropyltriethoxysilane (GPTS), and 3-glycidoxypropyltrimethoxysilane (GPTMS), were used. Among theses, GPTMS exhibits the best modification performance for fabricating GNP-incorporated epoxy composites. The effect of the silanization is evaluated using transmission electron microscopy (TEM), scanning electron microscopy, thermogravimetric analysis, and energy dispersive X-ray spectroscopy. The electrical and thermal conductivities are characterized. The epoxy/silanized GNPs exhibits higher thermal and electrical properties than the epoxy/raw GNPs due to the improved dispersion state of the GNPs in the epoxy matrix. The TEM microphotographs and Turbiscan data demonstrate that the silane molecules grafted onto the GNP surface improve the GNP dispersion in the epoxy.

$30-50{\mu}m$ 의 입도를 갖는 마이크로캡슐을 목표로 poly(acrylonitrile-co-methyl methacrylate)를 쉘로, n-octane을 코어로 하는 코어-쉘 구조의 열팽창 마이크로캡슐을 합성하였다. SPG 멤브레인 유화 후 현탁 중합하여 기존의 현탁 중합대비 균일한 입자를 합성하였다. 또한 네 가지 안정제 및 다섯 가지 가교제의 종류와 함량에 따른 캡슐의 합성을 진행하였다. Poly(vinyl alcohol)을 안정제로 하여 합성한 캡슐의 표면이 매끈하면서도 균일한 형태를 보였으며, 액체 탄화수소가 코어에 캡슐화된 양 또한 우수하였다. 또한 가교제로 1,4-butnaediol methacrylate (BDDMA)를 첨가했을 때 평균입경 $36.8{\mu}m$ 의 입자가 균일하게 합성되었다. 또한 BDDMA를 0.05 mol% 함량으로 합성한 입자의 캡슐화 정도가 가장 우수하였다. 【With aiming to prepare microcapsules having a particle size of $30-50{\mu}m$ , thermally expandable capsules with relatively uniform particle sizes consisting of a n-octane/poly(acrylonitrile-co-methyl methacrylate) core/shell structure were synthesized using SPG membrane emulsification and suspension polymerization. Four steric stabilizers and five crosslinking agents were employed. When poly(vinyl alcohol) as a stabilizer was used, the prepared capsules showed a smooth and regular morphology and the liquid hydrocarbon (n-octane) was well encapsulated in the core. When 1,4-butnaediol methacrylate (BDDMA) was used as a crosslinker, the uniform capsules with the average diameter of $36.8{\mu}m$ were synthesized. The capsules prepared with 0.05 mol% BDDMA showed the best encapsulation efficiency.】

Carbon foam (CFDT) has been fabricated by polycondensation of resorcinol and formaldehyde, using two kinds of polymethylmethacrylate as pore generators. In order to increase the specific surface area and improve the surface activity and wettability of the material in the electrolyte, physical activation (A-CFDT) with CO 2 and chemical modification (N-CFDT) with HNO 3 were carried out. CFDT showed poor supercapacitor properties, with a specific capacitance of 80.1 F/g at a 10 mV/s scan rate. N-CFDT exhibited the largest specific capacitance, with a value of 137.8 F/g at a 10 mV/s scan rate, when using 6 M KOH as the electrolyte. N-CFDT exhibited excellent cycle life stability as well.

Piezoresistive behavior of a stretchable poly(dimethylsiloxane) sheet with an interlayer of carbon nanotube in it (CNT-interlayered PDMS) was investigated based on two variables: individual length of CNT which forms the interlayer and degree of pre-tension of the sample during the preparation stage. The stress–strain curves exhibited good stretchable properties of the CNT-interlayered PDMS sheets, similar to that of neat PDMS sheets and better than that of CNT/PDMS composites. The electrical resistance changed almost linearly with applied strain and the results of piezoresistive experiments evidenced that these two variables are factors that indeed affect piezoresistive behavior. The results are explained by the pre-tension-derived wrinkled structure of the CNT layer and the effect of ultrasonication on the CNT length. The sensitivity is described by a gauge factor in the range 0.19–1.16. The samples show good conductivity even at large elongations (∼55%) and excellent properties in cyclic piezoresistive experiments at small (∼11%) as well as at large strain.

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