INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2022
·
IF 4.326
Wei Li,Ting Luo,Changxu Zhu,Bin Zhang,Bingqiang Cao
Graphene/hexagonal boron nitride nanocomposites with different dimensions have great application prospects in the field of lubrication due to their unique layered structure and excellent mechanical properties. However, due to their complex synthesis process, easy agglomeration, and poor stability, graphene/hexagonal boron nitride nanocomposites have not yet been applied in lubricating applications. Herein, a simple and green in situ laser irradiation method is proposed to construct two-dimensional (2D) reduced graphene oxide (rGO) nanosheets and zero-dimensional (0D) hexagonal boron nitride nanosphere 2D/0D nanocomposite (L-rGO/h-BN). During the one-step laser irradiation in liquid, the GO nanosheets were reduced to rGO nanosheets. Meanwhile, the hexagonal boron nitride (h-BN) transformed from nanoflakes to nanospheres via a pulsed laser heating and reshaping process and embedded into the multilayer graphene nanosheets. The spherical h-BN nanoparticles as interlayer support can maintain the 2D graphene with a more stable layered structure, while the insertion of graphene sheets also effectively inhibits the agglomeration of the spherical h-BN nanoparticles. Therefore, a hierarchical 2D/0D layered rGO/h-BN nanocomposite was formed. Importantly, such composite nanoparticles can well disperse in the lubricating oil without significant precipitation for over 30 days and show remarkably improved tribological performance. This is due to the synergistic lubricant effect of the deposition repair effect from rGO nanosheets reducing wear and micro-bearing effect from h-BN nanospheres reducing friction by changing sliding friction into rolling friction.
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ELECTROCHIMICA ACTA
·
2022
·
IF 7.336
Geng Cheng,Zhen Li,Erli Qu,Shan Ren,Dongmei Han,Min Xiao,Shuanjin Wang,Yuezhong Meng
It's of significant importance for the development of proton exchange membranes with low phosphoric acid (PA) uptake, high proton conductivity, better proton conduction stability and low production-costs for high temperature proton exchange membrane fuel cells (HT-PEMFCs). Featured with variable structure and diversified functionality, porous organic networks are newly emerged filler materials for polyelectrolytes in energy conversion field. In this work, a typical Schiff-base type porous polymeric network (SNW-1) with abundant N H sites was synthesized and blended with ether-type polybenzimidazole (PBI) for the first time. The thermal and chemical stability of the as-prepared composite membranes completely satisfy the practical requirements of HT-PEMFCs. The constructed consecutive proton conduction channels endow the composite membranes higher proton conductivity with low PA uptake. When the doping content of SNW-1 reached 30%, the PBI/30%-SNW-1 membrane showed much higher proton conductivity with lower PA uptake (114.0 mS cm −1 , 175.0%) comparing with those of the pristine PBI (67.3 mS cm −1 , 270.0%) at 160 °C. The PBI/ x %-SNW-1 membranes also exhibited better proton conduction stability. After 30 h of long-time evaluation at 140 °C, PBI/30%-SNW-1 composite membrane gives only an 8.47% decay of proton conductivity, which is lower than that of the pristine PBI (12.84%). The preparation procedure of PBI/ x %-SNW-1 composite membranes is simple, which provides a potential pathway for the development of high-performance proton exchange membrane for HT-PEMFCs.
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ENVIRONMENTAL RESEARCH
·
2022
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IF 8.431
Xiang Meng,Jianlong Wang,Lejin Xu
To further improve the treatment capacity of actual wastes, H + was introduced into the homogeneous Fenton system as a co-catalyst for dissolution and degradation of the mixed nuclear-grade cationic and anionic exchange resins. The effects of acid type and concentration, catalyst type and concentration, H 2 O 2 dosage, initial temperature, antifoaming agent and resin ratio were studied. The concentration of inorganic acid , type and concentration of catalyst had significant influence on the decomposition of mixed resins. The experimental results showed that when the mixing ratio of resins was 1:1, the initial temperature was 96 ± 1 °C, the amount of H 2 O 2 was 200 mL, and the concentration of H + /Fe 2+ was 1 M/0.1 M, complete dissolution and 79% weight reduction of mixed resins were obtained. Combined with density functional theory (DFT) calculations, cationic exchange resin and anionic exchange resin showed different reactivity in the experiment. Hydroxyl radicals (•OH) tended to attack –SO 3 - groups with more negative charges, and the barrier energy of –SO 3 - ion dissociation was 8.2 kcal/mol, which caused the cationic exchange resin to be easily destroyed. According to the characterization results, the characteristic intermediates were determined, indicating that desulfonation, valence change of nitrogen atom , and cleavage of long-chain carbon skeleton existed during the reaction, but incomplete oxidation still remained.
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PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2022
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IF 24.319
Dongxue Zhou,Xiangdong Xue,Xing Wang,Qingjie Luan,Ang Li,Liguo Zhang,Baozhen Li,Wenjun Dong,Ge Wang,Changmin Hou
Element doping is an excellent strategy to promote charge separation and reaction kinetics of photocatalyst, which plays significant role in accelerating the sustainable energy development process. Herein, Ni, In co-doped ZnIn 2 S 4 photocatalyst was prepared by a microwave-assisted solvothermal method. The rapid crystallization of ZnIn 2 S 4 resulted in partial In atoms substituted Zn atom during the formation of [ZnS] 4 layer. In doping in tetrahedral Zn sites increases the electron delocalization around In sites, hence reduces the electronic potential wells along Z axis. Ni doping in tetrahedral Zn sites decreases the negative charge on the S sits, which balances the H adsorption/desorption, further boosting the photocatalytic activity. As a result, Ni, In co-doped ZnIn 2 S 4 possess an optimal photocatalytic H 2 evolution property of 21.94 μmol·h −1 , which is nearly 1.8 and 6.1 times of In-ZnIn 2 S 4 (11.78 μmol·h −1 ) and ZnIn 2 S 4 (3.6 μmol·h −1 ).
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JOURNAL OF APPLIED POLYMER SCIENCE
·
2023
·Vol. 141
·期 6
·e54911
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IF 3
Mengqing Ren,Zixin Wu,Lili Wu,Bing Yu,Weilin Wu,Baoying Liu,Shengqiang Xiao
The pulley structure has been widely employed to improve mechanical properties. Polyrotaxane-based waterborne polyurethane (WPU) typically exhibits good tensile strength and Young's modulus. However, achieving outstanding self-healability of polyrotaxane-based WPU under mild conditions generally proves insufficient solely relying on host-guest interactions. Herein, a strategy that constructs a triple synergy of host-guest interaction, hydrogen bonds, and metal coordination bonds by sequentially introducing tannic acid (TA) and Fe 3+ is proposed to prepare polyrotaxane-based WPU with excellent mechanical performance and high self-healable capability. Besides the reversible non-covalent bonding contributing to intrinsic self-healing, the unique sliding motion of WPU's molecule chain acts as a driving force, promoting efficient contact among reversible bonds. Notably, benefiting from the sliding motion of β-cyclodextrin (β-CD) along a chain, the dynamic reconstruction of hydrogen bonds and metal coordination bonds, the resulting supramolecular WPU exhibited a tensile strength of 46.05 MPa and a toughness of 130.30 MPa, with satisfactory self-healing performance (tensile strength healing efficiency of more than 95%). This work enriches the self-healing mechanism and expands the concepts for the design of resilient self-healing environmentally friendly supramolecular WPU.
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Journal of Environmental Chemical Engineering
·
2023
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IF 7.7
Ruokun Jia,Jiayuan Deng,Xiaohang Yang,Ruisong Xue,Pengpeng Wang,Xingbo Bian,Qiyao Wang
Graphitic carbon nitride (CN) hold great promise as a photocatalyst for generating hydrogen energy via water splitting, owing to its remarkable ability to respond to visible light and its strong reduction capacity. However, the photocatalytic water splitting for H 2 evolution performance of pure CN was impeded by its low surface area, inadequate hydrophilicity, and unsatisfactory photoelectric conversion efficiency. Here we tackled these challenges by synthesizing a series of CN/H-ZSM-5 composites with varying amount of H-ZSM-5 zeolite using a straightforward thermal copolymerization method. The contact angle and N 2 adsorption-desorption measurements confirmed that the incorporated hydrophilic and porous H-ZSM-5 zeolite contribute to increased surface area and improved hydrophilicity of the CN/H-ZSM-5 composites. Meanwhile the resulting CN/H-ZSM-5 composites exhibited significant separation and migration enhancement of photoexcited charge carriers. Consequently, the optimized CN/H-ZSM-5 composite, containing 50 mg of H-ZSM-5 zeolite, demonstrated 13 times increase in photocatalytic H 2 production rate than that of pure CN. This work not only provided a competitively universal approach on the design of high-efficiency CN based photocatalyst, but also clarified the role of H-ZSM-5 zeolite in the H 2 evolution enhancement.
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ACS Omega
·
2020
·
IF 2.87
Ning Song,Shao-Peng Chen,Xiao-Wei Fan,Yu-Hui Tan,Wen-Juan Wei,Yun-Zhi Tang
The molecular design and regulation has shown bright future for constructing smart molecular materials such as ferroelectrics, dielectric switches, electro-optic effect, and so forth. Here, by poly-H/F substitution in a simple organic-inorganic hybrid 2[CH2FCH2NH3]·[CdCl4], 1 (CH2FCH2NH3 = fluorine ethylamine cation), we obtained two novel hybrids, namely, 2[CHF2CH2NH3]·[CdCl4], 2 (CHF2CH2NH3 = 2,2′-difluorine ethylamine cation) and 2[CF3CH2NH3]·[CdCl4], 3 (CF3CH2NH3 = 2,2′,2″-trifluorine ethylamine cation). Further investigations show that compounds 1, 2, and 3 experience solid reversible phase transitions with temperatures at 294, 319, and 329 K respectively. These unique phase transitions were confirmed by their remarkable dielectric and heat anomalies around the phase transition temperatures. X-ray single-crystal diffraction analyses before and after the phase transitions show that the order–disorder motions of F atoms and the twist motions from the 2D [CdCl4]2– framework lead to these solid reversible phase transitions. Also, the Hirshfeld surface calculation of compounds 1, 2, and 3 suggests that the increasing ratio of the F···F interaction from the intermolecular interaction makes a major contribution for the substantial increase of their phase transition temperatures.
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ACS Catalysis
·
2021
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IF 13.084
Xiangdong Long,Jia Wang,Guang Gao,Chao Nie,Peng Sun,Yongjie Xi,Fuwei Li
Direct oxidative amination of the sp3 C–H bond is an attractive synthesis route to obtain amides. Conventional catalytic systems for this transformation are based on transition metals and complicated synthesis processes. Herein, direct and efficient oxidative amination of the methyl C–H bond in a wide range of N-heterocycles to access the corresponding amides over metal-free porous carbon is successfully developed. To understand the fundamental structure–activity relationships of carbon catalysts, the surface functional groups and the graphitization degree of porous carbon have been purposefully tailored through doping with nitrogen or phosphorus. The results of characterization, kinetic studies, liquid-phase adsorption experiments, and theoretical calculations indicate that the high activity of the carbon catalyst is attributed to the synergistic effect of surface acidic functional groups (hydroxyl/carboxylic acid/phosphate) and more graphene edge structures exposed on the surface of carbon materials with a high graphitization degree, in which the role of acidic functional groups is to adsorb the substrate molecule and the role of the graphene edge structure is to activate O2.
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JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2021
·
IF 8.067
Yunwei Liu,Zelin Chen,Chang Liu,Jinfeng Zhang,Wenbin Hu,Yida Deng
We have developed an efficient strategy to synthesize an active and durable electrocatalyst of Pd hydride nanocubes (NCs). Instead of the traditional chemical method, the PdH 0.43 NCs are firstly prepared via a hydrogen diffusion procedure, followed by hydrothermal synthesis of an amorphous CuO layer encapsulating the PdH 0.43 NCs to prevent the hydrogen atoms from escaping. Obvious lattice expansion is demonstrated playing a pivotal role in the enhancement of their oxygen reduction reaction (ORR) activity and durability. The obtained PdH 0.43 @CuO NCs catalysts exhibit an ORR mass activity of 0.18 A mg −1 at 0.90 V versus reversible hydrogen electrode in an alkaline medium, which is about five times higher than that of commercial Pt/C. Accelerated durability tests show that there is only a 32 mV decay in half-wave potential even after 10,000 potential cycles, indicating the excellent stability of PdH 0.43 @CuO NCs. Density functional theory (DFT) calculations also indicate that, compared to Pd, PdH 0.43 has a lower limiting barrier to form OH − during the ORR process. The present study illustrates the importance of lattice expansion caused by hydrogen and offers an available strategy to design highly efficient and durable Pd-based electrocatalysts for alkaline fuel cells.
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JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Fuhai Liu,Maozhong Yi,Liping Ran,Yicheng Ge,Zhe Zhou,Ke Peng
C/C-BN-SiC composite was prepared by ceramic slurry infiltration combined with resin impregnation and carbonization, and the matrix with continuous distributed self-healing phase was obtained. In this study, the kinetic characteristics and oxidation behavior of the composites with various h-BN/SiC ratios in the temperature range of 600∼1300°C were studied by combining the isothermal oxidation test with the kinetic model. The optimal h-BN/SiC ratio balances the thermal stability and fluidity of the oxidized product, which not only has high thermal stability and low oxygen permeability to acts as an oxygen diffusion barrier but also has a certain fluidity to seal defects.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Liangfeng Luo,Yidi Wang,Siping Huo,Peng Lv,Jun Fang,Yang Yang,Bin Fei
CuS/CdS(H)/CdS(C) photocatalysts were synthesized via the hydrothermal method by employing thiourea , Cd(CH 3 COO) 2 ·3H 2 O and copper 1,4-benzenedicarboxylate MOF (CuBDC). The photocatalysts were characterized by XRD , XPS , BET, TEM and UV–vis diffuse reflectance spectra. Interestingly, hexagonal CdS (CdS(H)) and cubic CdS (CdS(C)) were formed with phase junctions in one step when CuBDC was introduced in the synthesis process, in addition, CuS nanoparticles were deposited on CdS. However, only hexagonal CdS was obtained without CuBDC. It demonstrated that CuBDC was not only the precursor of CuS but also the structural modifier for CdS. With the reduction of re-combination of photo-induced electrons and holes caused by phase junctions and the enhancement of visible-light absorptions due to the loading of CuS, all CuS/CdS(H)/CdS(C) photocatalysts had higher photocurrent densities under visible-light irradiation, and consequently the higher rates of H 2 production than pure CdS(H). Typically, the catalyst with 2.89 wt% of Cu showed a highest rate of H 2 evolution at 2042 μmol/g/h.
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RSC Advances
·
2018
·Vol. 8
·期 73
·42109-42115
·
IF 2.936
Myonghak Ri,Kwanghak Choe,Kumchol Kim,Yan Gao,Zhiyong Tang
BCN (boron carbon nitride) nanosheets are promising photocatalyst materials for solar fuel production by visible light-driven water splitting and CO2 reduction due to their tunable band gap and unique properties. C-doping into h-BN by thermal annealing makes possible the preparation of BCN nanosheets with photocatalytic activity under visible light irradiation, but it generally requires a very high temperature (>1250 °C) from the thermodynamic viewpoint. Here, we report a new method to prepare BCN nanosheets with visible light-photocatalytic activity at lower annealing temperature (1000 °C) than equilibrium by adding alkaline earth metal compounds. BCN nanosheets formed in borate melt show a clear layered structure, tunable bandgap and photocatalytic activity for water splitting and CO2 reduction under visible light illumination. This provides a direction for doping other elements into h-BN at low annealing temperature by alkaline earth metal borates.
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