본 연구에서는 과불화 알킬 사슬이 도입된 산화 그래핀(perfluoroalkyl-grafted graphene oxide, FGO)을 합성하고, 이를 과불소화계 고분자인 나피온(Nafion)에 복합화하여 바나듐 레독스 흐름 전지(vanadium redox flow battery, VRFB)용 이 온 교환 막을 개발하고자 하였다. FGO는 염기성 촉매 하에서 카르복실산기를 함유한 폴리(헥사플루오로프로필렌 옥사이드) (157 FSL, DuPont)의 카르복실산기와 GO의 에폭시기 간 개환 에스터화 반응을 통해 합성하였다. 합성된 FGO를 Nafion 기 지체에 함량을 달리하여 첨가한 복합막(N/FGO_X)을 제조하고, 함수율, 체적 안정성, 수소 이온 전도도, 바나듐 이온 투과도 및 셀 성능을 평가하였다. N/FGO 복합막은 Nafion 단일막 대비 낮은 함수율과 체적 변화율을 보였으며, FGO의 물리적 차단 효과에 의해 바나듐 이온 투과도가 감소하면서도 수소 이온 전도도를 유지하여 우수한 이온 선택도를 나타내었다. VRFB 단 위 셀 평가 결과, FGO가 도입된 복합막은 Nafion 단일막을 적용한 셀 대비 높은 방전 용량, 쿨롱 효율 및 에너지 효율을 유 지하였다.

하수 및 폐수 환경에서의 콘크리트 구조물은 부식성이 강한 황산 환경에 노출되어 석고와 에트링가이트 형성을 통해 심각한 열화를 초래한다. 본 연구는 이를 해결하기 위해 그래핀 나노플레이트릿(GNP)이 시멘트 모르타르의 내산성 향상에 미치는 효과에 대 해 연구하였다. GNP는 시멘트 중량 기준으로 0.05 wt.%, 0.10 wt.%, 0.15 wt.%로 혼합하였으며, 시편은 28일간의 수중양생 후 0.05 M 황산에 30일 동안 노출시켰다. 내구성 성능은 수분 흡수율, 질량 손실률, 잔류 압축강도 시험을 통해 평가했다. 그 결과, 0.10 wt% GNP는 수분 흡수율을 감소시키고, 질량 손실을 제한하며, 98.9%의 압축강도를 유지함으로써 내산성을 크게 향상시켰다. GNP 함량이 0.15 wt% 이상으로 증가하면 응집이 발생하여 열화가 심화되었다. 이 연구는 GNP를 최적 농도인 0.10 중량%로 첨가하면 황산에 대한 내구성이 향상되고 가혹 환경에서의 장기 인프라 개발 분야에 유망한 잠재력이 있다는 결론을 내렸다.

Graphene, mechanically exfoliated as a single-atom-thick two-dimensional (2D) material, is renowned for its exceptional carrier mobility and mechanical strength, making it a highly promising material for a wide range of applications; however, following the synthesis of large-area, high-quality graphene, quality degradation, such as tearing, frequently occurs during the transfer process. Currently, chemical vapor deposition (CVD) enables reliable synthesis of large-area graphene, and both wet and dry transfer methods are widely employed to transfer graphene onto various substrates. This study focuses on the wet transfer method to improve transfer efficiency by optimizing the interfacial adhesion among graphene, the polymethyl methacrylate (PMMA) support layer, and the target substrate. To enhance the efficiency of the wet transfer process, the PMMA concentration and ultraviolet ozone (UVO) treatment time were systematically optimized. As a result, a transfer yield of up to 97.16 % was achieved under optimized conditions consisting of 6 % PMMA concentration and 15 min of UVO exposure. This research contributes to the development of highly efficient graphene transfer techniques, which are crucial for reducing production costs and processing time in a wide range of advanced applications such as electronics, energy storage, biomedical devices, environmental monitoring, and materials science.

In order to optimize the manufacturing of polypropylene-derived few-layer graphene, an innovative utilization of nonsupported iron oxide nanoparticles generated under various fuel environment conditions was studied. Three distinct fuel combustion environment circumstances (fusion, fuel shortage, and fuel excess) produced a variety of Fe2O3 nanoparticles for cost-effective and green graphene deposition. XRD, H2- TPR, Raman, and TGA measurements were used to characterize both new and spent catalysts. Remarkably, the microstructure of the generated Fe2O3 nanoparticles could be controlled by the citric acid/iron nitrate ratio, ranging from spheroids ( Fe2O3(0)) to sheets ( Fe2O3(0.5-0.75)) and a hybrid microstructure that consists of sheets, spheroids, and interconnected strips ( Fe2O3(1-2)). According to fuel situation (citric acid/iron nitrate ratio, Fe2O3( 0-2)), various graphitization level and yields of graphene derivatives including sheets, ribbons, and onions have been developed. With the ideal fuel/oxidant ratio (ɸ = 1), the Fe2O3( 0.75) catalyst demonstrated the best catalytic activity to deposit the largest yield of highly graphitized few graphene layers (280%). Lean and rich fuel conditions (1 > ɸ > 1) have detrimental effects on the amount and quality of graphene deposition. It is interesting to note that in addition to graphene sheets, an excess of citric acid caused the production of metallic cores, hollow, and merged carbon nano-onions, and graphene nano-ribbons. It was suggested that carbon nano-onions be converted into graphene nano-ribbons and semi-onion shell-like graphene layers.

To improve the proton conductivity of the proton exchange membranes (PEM), an amino derivative with sulfonic acid groups was used to modify graphene oxide (GO), resulting in sulfonated graphene oxide (S-GO), which was then incorporated into a perfluorinated sulfonic acid (PFSA) matrix to fabricate a PFSA/S-GO composite membranes. Elevating the doping concentration of S-GO within the composite membrane has resulted in enhanced proton conductivity, outperforming the baseline PFSA membrane across a range of temperatures. Notably, this conductivity ascended to 291.89 mS/cm when measured at 80 °C under conditions of 100% RH. Furthermore, the strong interface interaction between sulfonated graphene oxide and perfluorinated sulfonic acid polymer endowed the composite proton exchange membrane with excellent thermal stability and mechanical strength.

This research developed a highly efficient voltammetric sensor, utilizing a carbon paste electrode (CPE) integrated with a novel ZnO-doped Pd–Pt bimetallic catalyst decorated with reduced graphene oxide (ZnO-Pt@Pd/rGO) and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([EMIM][Tf2N]), for the precise determination of sulfafurazole in real dextrose saline and tablet samples. The ZnO-Pt@Pd/rGO nanocomposite was synthesized through a one-stage synthesis process and characterized using SEM and EDS techniques. The comparison of the ZnO-Pt@Pd/rGO/[EMIM][Tf2N]/CPE with unmodified CPE, ZnO-Pt@Pd/rGO/CPE, and [EMIM][Tf2N]/CPE confirms the synergic effect of ZnO-Pt@Pd/rGO and [EMIM][Tf2N] as two conductive catalysts in fabrication of new sensor. The resulting sensor exhibited remarkable stability over a period of 2 months without compromising its efficiency for sulfafurazole detection. With a linear range of 0.001–250 μM (R2 = 0.9971) and LOD of 0.4 nM, ZnO-Pt@Pd/rGO/[EMIM][Tf2N]/CPE showcased exceptional accuracy and precision in the monitoring of sulfafurazole. Validation using real tablet and dextrose saline samples confirmed the sensor's outstanding capability in determining sulfafurazole, with relative recoveries ranging from 98.92 to 103.8% offering a promising solution for reliable sulfafurazole analysis in diverse pharmaceutical samples.

Polypropylene waste significantly contributes to environmental pollution due to its low biodegradability. Numerous experiments have shown that laser irradiation of polymers can lead to the conversion of laser-induced graphene (LIG). In this paper, the LIG formation process in polypropylene (PP), polydimethylsiloxane (PDMS), and polypropylene/polydimethylsiloxane (PP/PDMS) systems in a vacuum environment was simulated using molecular dynamics. The LIG yields and carbon network sizes of the systems in oxygen and vacuum environments at different temperatures were analyzed to determine the optimal temperature for upgrading PP to LIG. It was observed in all three systems that the LIG structure was formed. The structure was composed not only of six-membered carbon rings, but also of five-membered and seven-membered rings, resulting in out-of-plane fluctuations and bending. A vacuum environment and high temperature promote LIG formation with high yield, large size, and minimal defects. The current study provides theoretical guidance for optimizing the laser graphene process for PP assisted with PDMS in a vacuum environment and helps to understand the mechanism underlying the conversion from polyolefins to graphene under CO2 laser at the atomic level.

Self-assembled organic layers containing various functional groups between graphene layers were examined as gas barrier films. The formation of well-defined self-assembled layers of functionalized alkane molecules on graphene was confirmed by scanning tunneling microscopy (STM). The roles of these organic layers as gas barrier films could be quantitatively deduced by comparing their water vapor transmission rate (WVTR). The formation of self-assembled layers dramatically improved gas barrier properties by primarily blocking defects and gas molecule pathways. For functionalized alkanes containing hydrophilic groups, more enhanced gas barrier properties were observed compared to those with hydrophobic groups. These results clearly indicate that the primary role of the organic layers in gas barrier films is to block defects and the pathways of water molecules, with a secondary role of delaying the movement of water molecules through hydrogen bonding interactions.

In this study, we developed electrochemical sensors based on the composite of hydroxylated multiwalled carbon nanotubes (MWCNT-OH) and graphene for paraoxon-ethyl detection as pesticide residues in agricultural products. Chemical treatment was employed to produce MWCNT-OH from pristine MWCNT and its composite with graphene was subsequently characterized using FTIR, Raman spectroscopy, FESEM-EDX, TEM, and XPS techniques. The MWCNT-OH/graphene composite was employed as an electrode modifier on the glassy carbon electrode (GCE) surface, and its electroanalytical performances were studied using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. It was revealed the optimum composition ratio between MWCNT-OH and graphene was 2:8, for paraoxon-ethyl detection at pH 7. This could be attributed to the enhanced electrocatalytic activity in the MWCNT-OH/graphene composite which displayed a linear range of paraoxon-ethyl concentration as 0.1–100 μM with a lower detection limit of 10 nM and a good sensitivity of 1.60 μA μM cm− 2. In addition, the proposed sensor shows good reproducibility, stability, and selectivity in the presence of 10 different interfering compounds including other pesticides. Ultimately, this proposed sensor was tested to determine the paraoxon-ethyl concentrations in green apples and cabbage as samples of agricultural products. The obtained concentrations of paraoxon-ethyl from this proposed sensor show no significant difference with standard spectrophotometric techniques suggesting this sensing platform might be further developed as a rapid detection of pesticide residue in agricultural products.