Marine biofouling is a ubiquitous and serious problem in maritime engineering. Here, we reported an effective antifouling approach through facile fabrication of laminated-structured Cu-X composite ...coatings by plasma spraying of mechanically blended Cu and X powders, in which X is a type of metal nobler than Cu. The Cu-X coatings were designed to controlled release Cu ions from Cu/X micro-galvanic cells and thus to achieve long-term and effective antifouling performance. The effect of cathode X composition (i.e., Ni, stainless steel (SS), and Ti) on the micro-galvanic dissolution behavior and antifouling performance of the Cu-X coatings was systematically investigated. Results indicated that the cathode X composition exhibited little influence on the micro-galvanic dissolution mechanism of Cu-X coatings. Nevertheless, Cu ions release rate increased as follows: Cu-Ni coating < Cu-SS coating < Cu-Ti coating. Moreover, the Cu-X composite coatings exhibited long-lasting antifouling capability and remarkable antifouling efficiency of ~100%. Electrochemical test results revealed that the potential difference between Cu/X was the primary factor determining the difference of Cu dissolution rate and thus the Cu ions release rate between different Cu-X coatings. These results would open a new window for designing long-term and environment-friendly Cu-X antifouling coatings by employing various tunable bimetals.
Soot is a pollutant caused by combustion and is harmful to the environment and human health. Polycyclic aromatic hydrocarbons (PAHs) are considered the precursors of soot, thus exploring the growth ...mechanism of PAHs is conducive to reducing soot release. The mechanism by which a pentagonal carbon ring triggers the formation of curved PAHs has been demonstrated but studies on subsequent growth of soot are rare due to the lack of a suitable model. Buckminsterfullerene (C
60
), as one of the products from incomplete combustion under specific conditions, is similar in structure to soot particles with a surface that can be treated as curved PAH. Coronene (C
24
H
12
) is a typical seven-membered fused-ring PAH. In this study, C
60
was employed as a substitute for soot particles to investigate its effect on coronene growth reaction based on the hydrogen-abstraction/acetylene-addition (HACA) mechanism. Density functional theory (DFT) at the M062X/6-31G(d,p) level was adopted to investigate the potential energy surfaces (PESs) for these reactions. The high-pressure limiting rate constants for the relevant reactions were obtained based on transition state theory. The calculated results indicate that C
60
is easily hydrogenated, providing new pathways for coronene growth. Soot particles have a certain effect on the growth of PAHs. This study provides favorable support for further understanding the effect of soot on the growth pathway of PAHs.
Soot is a pollutant caused by combustion and is harmful to the environment and human health.
Soot is a pollutant caused by combustion and is harmful to the environment and human health. Polycyclic aromatic hydrocarbons (PAHs) are considered the precursors of soot, thus exploring the growth ...mechanism of PAHs is conducive to reducing soot release. The mechanism by which a pentagonal carbon ring triggers the formation of curved PAHs has been demonstrated but studies on subsequent growth of soot are rare due to the lack of a suitable model. Buckminsterfullerene (C60), as one of the products from incomplete combustion under specific conditions, is similar in structure to soot particles with a surface that can be treated as curved PAH. Coronene (C24H12) is a typical seven-membered fused-ring PAH. In this study, C60 was employed as a substitute for soot particles to investigate its effect on coronene growth reaction based on the hydrogen-abstraction/acetylene-addition (HACA) mechanism. Density functional theory (DFT) at the M062X/6-31G(d,p) level was adopted to investigate the potential energy surfaces (PESs) for these reactions. The high-pressure limiting rate constants for the relevant reactions were obtained based on transition state theory. The calculated results indicate that C60 is easily hydrogenated, providing new pathways for coronene growth. Soot particles have a certain effect on the growth of PAHs. This study provides favorable support for further understanding the effect of soot on the growth pathway of PAHs.
Soot is a pollutant caused by combustion and is harmful to the environment and human health. Polycyclic aromatic hydrocarbons (PAHs) are considered the precursors of soot, thus exploring the growth ...mechanism of PAHs is conducive to reducing soot release. The mechanism by which a pentagonal carbon ring triggers the formation of curved PAHs has been demonstrated but studies on subsequent growth of soot are rare due to the lack of a suitable model. Buckminsterfullerene (C
), as one of the products from incomplete combustion under specific conditions, is similar in structure to soot particles with a surface that can be treated as curved PAH. Coronene (C
H
) is a typical seven-membered fused-ring PAH. In this study, C
was employed as a substitute for soot particles to investigate its effect on coronene growth reaction based on the hydrogen-abstraction/acetylene-addition (HACA) mechanism. Density functional theory (DFT) at the M062X/6-31G(d,p) level was adopted to investigate the potential energy surfaces (PESs) for these reactions. The high-pressure limiting rate constants for the relevant reactions were obtained based on transition state theory. The calculated results indicate that C
is easily hydrogenated, providing new pathways for coronene growth. Soot particles have a certain effect on the growth of PAHs. This study provides favorable support for further understanding the effect of soot on the growth pathway of PAHs.
Durability is one of the most key problems for the widespread commercialization of proton exchange membrane fuel cells (PEMFCs). Proton exchange membranes (PEMs) are pivotal components of the PEMFCs ...and their chemical stability is thus an important for the PEMFCs reliability. The incorporation of Ce-based radical quenchers such as ceria in PEMs can obviously alleviate the chemical deterioration of PEMs. Nevertheless, cell performance may decrease due to the presence of Ce-based radical quenchers. Therefore, a trade-off between cell performance and chemical stability of Ce-based radical quenchers containing PEM appears. To solve this issue, we developed a Ce-based metal organic framework Ce-BTC MOF with high radical trapping and proton-conducting properties. The Ce-BTC MOFs are introduced into the PFSA membrane to enhance the chemical stability and proton conductivity of the PFSA membrane. The PFSA/Ce-BTC membrane showed a maximum power density of 1.71 W/cm2 at 75 °C under 80％RH. After OCV test, PFSA/Ce-BTC membrane exhibited a decay of 0.56 mV/h after 120 h; pristine PFSA and Nafion membrane exhibited accelerated decay (for pristine PFSA, 1.72 mV/h; for Nafion membrane, 2.36 mV/h). Therefore, introduction of Ce-BTC MOFs offers an active defence approach to enhance the chemical stability of PEMFCs without sacrificing their cell performance.
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•A Ce-based metal organic framework (Ce-BTC MOF) was prepared by solvothermal method.•The Ce-BTC MOF has high radical scavenging and proton-conducting properties.•The fabricated membrane has excellent chemical durability and cell performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Carbon monoxide (CO) produced by automobile exhaust emissions and fuel combustion is one of the domain pollutants severely causing experimental and human health problems, which catalytic combustion ...at low temperature is an effective way to remove. Here, a Ni and N co-doped double vacancy graphene catalyst (NiNx-Gr) was established for the combustion of CO at low temperature by regulating the number of N atoms. Based on the density function theory (DFT) method, the reaction mechanisms of CO catalytic combustion on different surface were developed, and the rate constants were also calculated by the means of transition state theory (TST). All NiNx-Gr catalysts exhibit excellent stability and catalytic performance, among which NiN3-Gr is the most outstanding. Molecular dynamics (MD) simulation results show that NiN3-Gr can still exist stably at the temperature of 1000 K. The calculation results of the potential energy surface show that CO is most advantageously oxidized by the TER mechanism on NiN3-Gr with a reaction energy barrier of only 1.71 eV. Furthermore, the results of the rate constants also indicate that NiN3-Gr is the most effective catalyst for CO combustion. All these results demonstrate that NiN3-Gr may serve as a high-performance material for catalytic CO combustion, which may offer some design insights for the experiments. This work not only proposes a catalyst for CO combustion, but also depicts a reasonable reaction mechanism in detail, which serves as a solid starting point for the further understanding of catalytic combustion kinetics of CO under low temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Al2O3-PDMS-Cu coating was developed by plasma spraying followed by PDMS infiltration.•The surface hydrophobicity and fouling release property of PDMS were well preserved.•High mechanical robustness, ...abrasion resistance and adhesive strength were obtained.•Remarkable inhibition ability against adherence of bacteria and algae was realized.•The superior antifouling ability resulted from dual-functional antifouling strategy.
Marine biofouling is a worldwide challenge that needs to be solved urgently. Poly(dimethylsiloxane) (PDMS)-based fouling release coatings with low surface free energy (SFE) could effectively inhibit biofouling. Nevertheless, their poor mechanical durability, adhesive strength, and antifouling performance under static conditions significantly limit their applications. Herein, a novel mechanically robust Al2O3-PDMS-Cu composite coating with strong adhesive strength and remarkable antifouling performance was developed. The Al2O3-PDMS-Cu coating loaded with a small amount of Cu was fabricated by infiltrating PDMS into plasma-sprayed micro/nano-scaled porous Al2O3-Cu coating. Results showed that the fabrication of this Al2O3-PDMS-Cu coating did not alter the surface hydrophobicity and SFE of PDMS significantly, thus presenting little influence on its inherent fouling release property. After rigorous abrasion test, the Al2O3-PDMS-Cu coating presented remarkably improved surface hydrophobicity due to the exposure of micro/nano structure, rather than falling off as that of PDMS coating. The combination of excellent abrasion resistance and one order of magnitude higher adhesive strength and hardness than PDMS coating contributed to the outstanding mechanical robustness of Al2O3-PDMS-Cu coating. Additionally, the antifouling assays against marine bacteria adhesion (95% reduction rate for Escherichia coli. (E. coli)) and algae attachment (96% and 94% reduction rates for Chlorella and Phaeodactylum tricornutum (P. tricornutum), respectively after 21 days of incubation) demonstrated the superior antifouling performance of the Al2O3-PDMS-Cu coating. Thus, a high-performance Al2O3-PDMS-Cu antifouling coating with excellent mechanical robustness and long-term antifouling performance was achieved via the combination of mechanical durability of Al2O3 skeleton and the dual-functional antifouling strategy, i.e., the fouling release property of PDMS and fouling resistance of Cu.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The property of perfluorinated sulfonic acid (PFSA) membranes depends not only on the ion exchange capacity (IEC), but also on the chemical structure of the functional side-chain and the ...phase-separation morphology. Two PFSA membranes, the long side-chain (LSC) and the short side-chain (SSC), have been investigated to study the structure–property relationship, covering the ionic domain structure and the proton transport. The proton conductivity of the SSC PFSA membrane is 143 and 209 mS/cm at 30 °C and 80 °C in water, which is 30–40% higher than that of the LSC PFSA membrane (103 and 161 mS/cm). The bound-to-free water ratio in the hydrated membranes was analyzed by differential scanning calorimetry and Raman spectroscopy, which show that a higher ratio accounts for the improved proton conductivity of the SSC PFSA membrane. The chain mobility was analyzed by solid-state nuclear magnetic resonance, which reveals that the side chain of the SSC membrane more readily self-assembles. This result was verified by the morphology from transmission electron microscopy. The small-angle X-ray scattering results show that the SSC PFSA membrane exhibits smaller domain spacing between the ionic clusters in dehydrated membranes. These observations, a larger ionic cluster and smaller domain spacing in the dehydrated SSC membrane, indicate a reduced size of the hydrophobic assembly feature domains, and the ionic channel connectivity is better in the SSC, which can be another key issue for its improved proton conductivity, in addition to the higher IEC and higher proton mobility.
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IJS, KILJ, NUK, PNG, UL, UM
Methane catalytic combustion is a significant technique in the fields of enhanced combustion, methane removal, and methane detection with the development of the natural gas industry and the demand ...for low-carbon combustion. Here, using a facile flame pyrolysis technique, two different types of Ni-CeO2 catalysts for methane combustion were synthesized from metal-organic framework (MOF) and metal salt (MS). Moreover, the Mars–van Krevelen (MvK) mechanism was investigated by combining kinetics with density functional theory (DFT) calculation. The performance shows that Ni-CeO2(BTC) catalysts give high activity owing to the large surface area, abundant Ni cations, and adsorbed oxygen. The high intrinsic activity is also related to a large number of oxygen vacancies which are essential for the MvK mechanism. In terms of kinetic analysis, the methane concentration determines the catalysis, and a redox MvK mechanism shows a good description of the experimental results. DFT calculations further clarify that, according to the MvK mechanism, the reduction of the active site is via dissociative adsorption of CH of CH4 on the catalytic site NiOCe, resulting in the formation of an oxygen vacancy, followed by dissociation of gas-phase oxygen on the oxygen vacancy to reoxidize the active site. Summarily, the MvK mechanism dominates the methane heterogeneous combustion over Ni-CeO2 and provides insight into the catalyst design for strengthening combustion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The synergistic effects between organic antioxidants with metal ion chelation ability and inorganic radical scavengers were investigated. The different perfluorosulfonic acid (PFSA) composite ...membranes were prepared by single doping and codoping of alizarin (AZR) and cerium ions. AZR and cerium ion codoping not only significantly enhanced the oxidative stability of the membrane but also lessened both the migration of cerium ions from the membrane and the ionic cross-linkages of cerium ions with sulfonic acid groups. AZR/Ce codoping of the PFSA composite membrane exhibited a maximum power density of 966 mW cm−2 at 75 °C under 80% RH, which was 89.45% of that of the pristine PFSA membrane, whereas only 79.37% remained for cerium ion single doping of the membrane under the same conditions. The AZR/Ce-codoped PFSA composite membrane released much less fluoride than the single-doped PFSA, AZR, or cerium ion composite membranes. The antioxidation effects of AZR/Ce codoping of the PFSA composite membrane were also studied by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), electrochemical hydrogen crossover analysis, and cell performance analysis. Notably, the open-circuit voltage (OCV) test indicated that the AZR/Ce-codoped PFSA composite membrane was still viable after 456 h of testing, whereas the other membranes were seriously damaged.
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•Promote chemical stability of the membrane by co-doping organic antioxidant and inorganic radical scavenger.•Synergy effects of alizarin and cerium ions on scavenging free radicals.•About 89.45% of the original power density is retained after co-doping alizarin and cerium ions.•PFSA/AZR4/Ce2 composite membrane is still very alive after 456h OCV test.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
