Post-treatment Process Research Articles

Nitrogen Pretreatment of Growth Substrates for Vacancy-Saturated MoS2.

Two-dimensional transition-metal dichalcogenides (2D TMDCs) are considered promising materials for optoelectronics due to their unique optical and electric properties. However, their potential has been limited by the occurrence of atomic vacancies during synthesis. While post-treatment processes have demonstrated the passivation of such vacancies, they increase process complexity and affect the TMDC's quality. We here introduce the concept of pretreatment as a facile and powerful route to solve the problem of vacancies in MoS2. Low-temperature nitridation of the sapphire substrate prior to growth provides a nondestructive method to MoS2 modification without introducing new processing steps or increasing the thermal budget. Spectroscopic characterization and atomic-resolution microscopy reveal the incorporation of nitrogen from the sapphire surface layer into chalcogen vacancies. The resulting MoS2 with nitrogen-saturated defects shows a decrease in midgap states and more intrinsic doping as confirmed by ab initio calculations and optoelectronic measurements. The demonstrated pretreatment method opens up new routes toward future, high-performance 2D electronics, as evidenced by a 3-fold reduction in contact resistance and a 10-fold improved performance of 2D photodetectors.

Effects of Acid Leaching Post-Treatment Process on the Structural Stability of Pt-Based Intermetallic Catalysts for Fuel Cell Applications

Accelerating the commercialization of polymer electrolyte membrane fuel cells (PEMFCs) requires urgent improvement of a catalyst for oxygen reduction reaction (ORR) that uses expensive precious metals. It is also important to consider the durability of the catalyst, which can affect its performance even after long-term use.In this study, we synthesized a platinum-cobalt (Pt-Co) catalyst with a platinum (Pt) shell and an intermetallic inner core through the acid-leaching post-treatment process. By introducing a transition metal, we greatly improved the ORR activity, while controlling the intermetallic and core-shell structure greatly improved the catalyst's structural stability and durability. We confirmed through X-ray diffraction (XRD) that the Pt-Co compound was aligned in an intermetallic structure, and that the structure was maintained even after the acid leaching post-treatment. In the half-cell test, L10-PtCo@Pt/C, exposed to 0.5 M sulfuric acid solution for 6 hours, exhibited a 3.9-fold increase in mass activity and a 3.3-fold increase in specific activity compared to commercial Pt/C. Additionally, the electrochemical active surface area (ECSA) of L10-PtCo@Pt/C remained stable even after 30,000 cycles, with an insignificant change of 8% or less, while commercial Pt/C decreased by 30% or more. Nevertheless, when acid treatment was applied for longer than this condition, the increase in performance and its retention were significantly reduced. This is due to the fact that with longer acid leaching times, the Pt shell of the catalyst becomes thicker, resulting in a limitation of the alloying effect of the internal intermetallic core.Our study proposes an optimal combination of Pt-Co intermetallic core and Pt shell through precise control of acid leaching post-treatment process. Pt-Co catalysts with well-aligned intermetallic core and the moderate thickness of Pt shell structure can offer a promising solution for improving the performance and durability of PEMFCs, thereby paving the way for their widespread commercialization.

Salt-Induced High-Density Vacancy-Rich 2D MoS2for Efficient Hydrogen Evolution.

Emerging non-noble metal 2Dcatalysts, such as molybdenum disulfide (MoS2), hold great promise in hydrogen evolution reactions. The sulfur vacancy is recognized as a key defect type that can activate the inert basal plane to improve the catalytic performance. Unfortunately, the methodof introducing sulfur vacancies is limited and requires costly post-treatment processes. Here, a novel salt-assisted chemical vapor deposition (CVD) method is demonstrated for synthesizing ultrahigh-density vacancy-rich 2H-MoS2, with a controllable sulfur vacancy density of up to 3.35×1014cm-2. This approach involves a pre-sprayed potassium chloridepromoter on the growth substrate. The generation of such defects is closely related to ion adsorption in the growth process, the unstable MoS2-K-H2O triggers the formation of sulfur vacancies during the subsequent transfer process, and it is more controllable and nondestructive when compared to traditional post-treatment methods. The vacancy-rich monolayer MoS2 exhibits exceptional catalytic activity based on the microcell measurements, with an overpotential of ≈158.8mV (100mAcm-2) and a Tafel slope of 54.3mVdec-1 in 0.5m H2SO4 electrolyte. These results indicate a promising opportunity for modulating sulfur vacancy defects in MoS2 using salt-assisted CVD growth. This approach represents a significant leap toward achieving better control over the catalytic performances of 2D materials.

Optimizing the hydrothermal post-treatment process for a TiO2/WO3 hybrid coating to enhance the photocatalytic degradation of methylene blue under visible light

WO3 nanoparticles were grown hydrothermally on porous titania (TiO2) PEO-coated on Ti in an alkaline electrolyte using pulsed direct current mode. To achieve the best photodegradation of methylene blue (MB) mediated by the PEO/HT hybrid coatings under visible illumination, hydrothermal parameters including precursor concentration, temperature, and time were optimized. In this sense, increasing the Na2WO4 concentration resulted in a decrease in porosity percentage and an increase in average particle size. At an optimal precursor concentration of 0.005 M, the TiO2/WO3 hybrid coating exhibited 67% degradation compared to ∼47% degradation for a bare TiO2 coating. Based on the LaMer diagram, the growth mechanism of WO3 crystals under the hydrothermal process was described. The calculated band gap of the PEO/HT coatings reduced from 3.0 eV to 2.68 eV with an increase in W-based precursor content through the hydrothermal process. Consequently, the improvement in photocatalytic performance was attributed to the participation of more WO3 nanoparticles and the expansion of the light absorption range of TiO2 up to the visible light range. Increasing the hydrothermal temperature led to an increase in crystallinity and particle size due to growth, but a decrease in porosity. The optimal photocatalytic performance was achieved for the hybrid coatings at a concentration of 0.005 M, with a hydrothermal temperature of 120 °C and treatment time of 18 h, resulting in ∼88% degradation of methylene blue after 360 min of irradiation. The study of photoactivity on a pollutant model indicates that the resulting activity is primarily influenced by the morphology of hybrid coatings, followed by their specific surface area.

Surface Treatment of Polymer Membranes for Effective Biofouling Control.

Membrane biofouling is the consequence of the deposition of microorganisms on polymer membrane surfaces. Polymeric membranes have garnered more attention for filtering and purifying water because of their ease of handling, low cost, effortless surface modification, and mechanical, chemical, and thermal properties. The sizes of the pores in the membranes enable micro- and nanofiltration, ultrafiltration, and reverse osmosis. Commonly used polymers for water filter membranes are polyvinyl chloride (PVA), polyvinylidene fluoride (PVDF), polyamide (PA), polyethylene glycol (PEG), polyethersulfone (PES), polyimide (PI), polyacrylonitrile (PAN), polyvinyl alcohol (PA), poly (methacrylic acid) (PMAA), polyaniline nanoparticles (PANI), poly (arylene ether ketone) (PAEK), polyvinylidene fluoride polysulfone (PSF), poly (ether imide) (PEI), etc. However, these polymer membranes are often susceptible to biofouling because of inorganic, organic, and microbial fouling, which deteriorates the membranes and minimizes their lives, and increases operating costs. Biofouling infection on polymer membranes is responsible for many chronic diseases in humans. This contamination cannot be eliminated by periodic pre- or post-treatment processes using biocides and other chemicals. For this reason, it is imperative to modify polymer membranes by surface treatments to enhance their efficiency and longevity. The main objective of this manuscript is to discuss application-oriented approaches to control biofouling on polymer membranes using various surface treatment methods, including nanomaterials and fouling characterizations utilizing advanced microscopy and spectroscopy techniques.

The Impact of Post-Processing Temperature on PLGA Microparticle Properties.

Biodegradable poly(lactide-co-glycolide) (PLGA) microparticles loaded with either risperidone or naltrexone were prepared from an emulsification homogenization process. The objective of this study was to determine the impact the post-treatment temperature has on the properties and subsequent performance of the microparticles. The post-treatment temperature of an ethanolic solution was characterized from 10 ~ 35ºC for the naltrexone and risperidone micropartilces. The wash temperature resulted in a typical triphasic in vitro release pattern at low wash temperatures or a biphasic pattern consisting of an elevated release rate at higher post-treatment temperatures. The post-treatment temperature largely influences the particle morphology, residual solvent levels, glass transition temperature, and drug loading and is molecule dependent, whereby these characteristics subsequently influence the drug release rate. The study highlights the importance of both the post-treatment process and control during manufacturing to obtain a formulation within the desired product profile.

Greywater treatment performance of a pilot-scale membrane bioreactor and characteristics of bacterial biofilm signatures in permeate effluent

Treated greywater has a high potential for water reuse. However, the post-treatment processes of reclaimed greywater may face biofouling problems due to biofilm formation. In the present study, the greywater treatment performance of a pilot-scale membrane bioreactor (MBR) was evaluated, and the effect of a dominant bacterial biofilm growing on the Pall ring media placed in the permeate pipeline was investigated. The MBR was operated for 125 days with a constant hydraulic retention time of 2 days under complete sludge retention. The treatment performance in terms of the levels of organic compounds, ammonium nitrogen, suspended solids, total coliforms, and Escherichia coli was >90 %. During the operation, a high relative abundance (>70 %) of the following bacterial phyla was observed within the MBR and the bacterial biofilm: Proteobacteria, Chloroflexi, Actinobacteria, and Planctomycetes. Furthermore, the following bacterial orders were predominantly observed in the biofilm: Sphingomonadales, Burkholderiales, and Planctomycetes. Acidovorax, Methylibium, Blastomonas, and Planctomyces were the important genera identified in the biofilm. Interestingly, the present study revealed that these bacterial species were predominant and well adapted in treated greywater containing various surfactant and detergent components. Knowledge of the predominant bacterial species in the biofilm could enable to select the appropriate disinfection method and prevent the biofouling of the reverse osmosis (RO) membrane, which can facilitate further application of the MBR-RO process for water reuse.

Investigation of the post-treatment process for improving corrosion behaviors and adhesion strength of plasma electrolytic oxidation (PEO) coatings on pure copper

The post-treatment processes of plasma electrolytic oxidation (PEO) coatings for corrosion behaviors and adhesion strength are investigated by surface analysis and electrochemical measurements. When the PEO coating is treated with high-temperature oxidation (HTO), silane coupling agent (SCA) mixed with benzotriazole (BTA) exhibits the optimal corrosion behaviors and adhesion strength, the icorr decreases to 0.65 ± 0.35 μA/cm2, ip decreases to 4.37 ± 0.42 μA/cm2, the Epit increases to 369.6 ± 0.4 mVSCE and the bonding strength increases to 14.2 MPa. That was mainly attributed to the corrosive medium with a longer diffusion path to the interface. Moreover, only the HTO treatment at 150 °C showed superior properties for long-time service, the icorr was 2.00 ± 0.17 μA/cm2, ip was 12.30 ± 0.09 μA/cm2, the Epit was −4.7 ± 0.2 mVSCE and the bonding strength was 10.0 MPa. That was ascribed to both the outer hydroxide and the inner oxide depicted the higher compactness.

Microporous exposure on catalytic performance of MoVNbTeOx mixed metal oxides in the oxidative dehydrogenation of ethane

The catalytic performance of the non-purified MoVNbTeOx catalyst was optimized by changing the composition of the synthesis gel method in the hydrothermal synthesis process. However, the enhancement in activity was more pronounced for the post-treatment process of the non-purified catalyst. The catalytic performance of non-purified MoVNbTeOx catalysts and phase-pure M1 catalysts in the oxidative dehydrogenation of ethane (ODHE) were enhanced by water agitation post-treatment. The results showed that the phase-pure M1 catalyst obtained by treating the MoVNbTeOx catalyst with nitric acid had an increased activity per unit mass, but with a mass loss of catalyst materials during the purification process. After several days of post-treatment with water agitation, the catalytic activity of the non-purified MoVNbTeOx and the M1 samples gradually increased and stabilized, where both catalysts had a comparable catalytic performance. All the samples were systematically characterized, showing that the catalytic performance of the samples was mainly correlated with the enhanced specific surface area/pore volume. The results show that for the hydrothermally synthesized MoVNbTeOx catalysts, the reaction takes place in the micropores and the key to improve the performance of MoVNbTeOx catalysts is to effectively expose the active sites. Physical post-treatment process that does not require nitric acid or hydrogen peroxide for purification is also effective in enhancing catalyst activity by boosting the active site.

Three birds, one-stone strategy for synthesis of hierarchically arrayed defective MnCo2O4@NF catalyst for photothermal preferential oxidation of CO in H2-rich streams

A novel strategy with the “three birds, one stone” effect has been proposed to enhance the catalytic performance of cobalt manganese spinel catalysts for photothermal CO-PROX in H2 streams. The approach involves fabricating hierarchically arrayed defective MnCo2O4@ Nickel foam (NF) through a simple hydrothermal post-treatment and partial recrystallization process. Three synergetic effects were induced by the hydrothermal posttreatment of MnCo2O4: (i) the creation of a hierarchically arrayed morphology that strengthens light absorption and photo-to-thermal conversion, supported by finite-element method (FEM) simulations; (ii) the increased vacancy structures to alleviate significant electron-hole recombination; and (iii) abundant oxygen vacancy to facilitate oxygen adsorption and activation. These effects result in the unique hierarchically arrayed morphology and superior structural properties of MnCo2O4 spinel, which significantly enhances the photothermal synergism and catalytic activity of MnCo2O4@NF in photothermal CO-PROX driven by simulated solar light. This work provides a simple and facile strategy for developing hierarchical and defective MnCo2O4 spinel photothermal materials.

Comparison between friction stir processing and laser remelting processes of cold sprayed metallic composite coatings

Friction stir processing (FSP) is applied for the post-treatment of an Al-Cu-Ni cold spray metal composite in order to produce an alloy coating. The results are compared with laser remelting of the same material. It was shown that both post-treatment procedures form an alloy containing new intermetallic phases AlNi and Al2Cu initially absent in the as-sprayed material. The integrity of the coating treated by FSP was significantly higher than the laser-treated one due to the absence of material melting, which can introduce significant porosity. Thus, FSP could be considered an efficient post-treatment process of cold sprayed composite coatings leading to the improvement of the coating uniformity and modification of the phase composition.

A Review of Freeze Casting: Preparation Process, Modified Methods, and Development Tendency

Abstract: Fabricating materials with nacre-like structure have received considerable attention as it shows an excellent combination of mechanical strength and toughness. A considerable number of researchers have reported the preparation method of bionic structure, such as layer-by-layer assembly, vacuum filtration, coextrusion assembly, electrophoresis deposition, water-evaporation-induced assembly, 3D printing, and freeze casting. Compared with other techniques, freeze casting, known as ice templating, is an environmentally friendly, prolongable, and potential method, so it has been rapidly developing and widely researched in recent decades. In this review, the front six methods with their benefits and limitations are briefly introduced. Then, the freeze casting technique with the preparation process and modified technique is emphatically analyzed. Finally, the future tendencies of materials application and technique application are discussed. Freeze casting consists of suspension preparation, solidification, sublimation, and post-treatment processes. The mechanism and influence of parameters during suspension preparation and solidification processes are principally discussed. It must be pointed out that the performance and structure of samples are closely related to the model and external force. Besides, the adjustable process parameters of freezing casting are a strong guarantee of obtaining the target product. The purpose of this review is to promote freeze casting workers to understand the influence of parameters and enlighten them in new experimental designs.

Numerical simulation of a managed aquifer recharge system designed to supply drinking water to the city of Amsterdam, The Netherlands

Managed aquifer recharge (MAR) is increasingly used to secure drinking water supply worldwide. The city of Amsterdam (The Netherlands) depends largely on the MAR in coastal dunes for water supply. A new MAR scheme is proposed for the production of 10 × 106 m3/year, as required in the next decade. The designed MAR system consists of 10 infiltration ponds in an artificially created sandbank, and 25 recovery wells placed beneath the ponds in a productive aquifer. Several criteria were met for the design, such as a minimum residence time of 60 days and maximum drawdown of 5 cm. Steady-state and transient flow models were calibrated. The flow model computed the infiltration capacity of the ponds and drawdowns caused by the MAR. A hypothetical tracer transport model was used to compute the travel times from the ponds to the wells and recovery efficiency of the wells. The results demonstrated that 98% of the infiltrated water was captured by the recovery wells which accounted for 65.3% of the total abstraction. Other sources include recharge from precipitation (6.7%), leakages from surface water (13.1%), and natural groundwater reserve (14.9%). Sensitivity analysis indicated that the pond conductance and hydraulic conductivity of the sand aquifer in between the ponds and wells are important for the infiltration capacity. The temperature simulation showed that the recovered water in the wells has a stable temperature of 9.8–12.5 °C which is beneficial for post-treatment processes. The numerical modelling approach is useful and helps to gain insights for implementation of the MAR.

Nano-Cavities within Nano-Zeolites: The Influencing Factors of the Fabricating Process on Their Catalytic Activities.

Titanium silicalite-1 (TS-1) is a milestone heterogeneous catalyst with single-atom tetrahedral titanium incorporated into silica framework for green oxidation reactions. Although TS-1 catalysts have been industrialized, the strategy of direct hydrothermal synthesis usually produces catalysts with low catalytic activities, which has still puzzled academic and industrial scientists. Post-treatment processes were widely chosen and were proven to be an essential process for the stable production of the high-activity zeolites with hollow structures. However, the reasons why post-treatment processes could improve catalytic activity are still not clear enough. Here, high-performance hollow TS-1 zeolites with nano-sized crystals and nano-sized cavities were synthesized via post-treatment of direct-synthesis nano-sized TS-1 zeolites. The influencing factors of the fabricating processes on their catalytic activities were investigated in detail, including the content of alkali metal ions, the state of titanium centers, hydrophilic/hydrophobic properties, and accessibility of micropores. The post-treatment processes could effectively solve these adverse effects to improve catalytic activity and to stabilize production. These findings contribute to the stable preparation of high-performance TS-1 catalysts in both factories and laboratories.

A facile route for the synthesis of high‐entropy transition carbides/borides at low temperatures

AbstractAs the main candidates in the field of ultra‐high temperature ceramics, high entropy carbides/borides (HECs/HEBs) have good oxidation resistance properties, high hardness, as well as excellent thermal and electrical conductivities, which are the focused points of research nowadays. In the current study, (Hf,Ta,Zr,Nb,Mo,Ti)C powders were successfully synthesized by a three‐step process, including the mixing process of raw oxides and carbon black with spaying Fe(NO3)3 solution, carbothermal reduction and subsequent calcium posttreatment. For the preparation of (Hf,Ta,Zr,Nb,Mo,Ti)B2 powders, during the calcium posttreatment process, equal stoichiometric ratio of B4C was added for the purpose of boriding reaction. The relevant X‐ray diffraction and SEM characterizations indicate the successful preparations of face‐centered cubic HECs and hexagonal HEBs. However, slight Mo local segregation was found in the prepared (Hf,Ta,Zr,Nb,Mo,Ti)B2 powders. The iron generated from Fe(NO3)3 promotes the solid solution process between monocarbides during the carbothermal reduction process via the dissolution‐diffusion‐precipitation mechanism. In the calcium posttreatment process, the liquid calcium ensures the boriding reaction take place at a low temperature. In addition, the residual carbon could be combined with calcium to generate CaC2 which is easy to be removed by acid leaching, and meanwhile, the added Fe could also be finally eliminated to produce pure HEC/HEB powders. The current method does not require the long‐time high energy ball milling of raw materials, but only simple and mild mixing is enough. Therefore, such a facile route has a great potential application prospect for industrially preparing high entropy phase powders in a large scale.

Seashell-Inspired Switchable Waterborne Coatings with Complete Biodegradability, Intrinsic Flame-Retardance, and High Transparency

Inspired by the "brick-and-mortar" structure and the whole lifecycle eco-friendliness of seashells, we have constructed a proof-of-concept and environmentally friendly coating with switchable aqueous processability, complete biodegradability, intrinsic flame retardance, and high transparency, via using natural biomass and montmorillonite (MMT). We first designed and synthesized cationic cellulose derivatives (CCD) as the macromolecular surfactants, which effectively exfoliated MMT to obtain nano-MMT/CCD aqueous dispersions. Subsequently, via a simple spray-coating process and a post-treatment process with a salt aqueous solution, the transparent, hydrophobic, and flame-retardant coating was fabricated with a "brick-and-mortar" structure. The resultant coating exhibited an extremely low peak heat release rate (PHRR) of only 17.3 W/g, which is 6.3% of cellulose PHRR. Moreover, it formed a lamellar and porous structure once ignited. Thus, this coating could effectively protect combustible materials from fire. In addition, the coating had a high transparency (>90%) in the range of 400-800 nm. After use, the water-resistant coating was converted into a water-soluble material by using a hydrophilic salt aqueous solution, which then could be easily removed by water. Furthermore, the CCD/nano-MMT coating was completely degradable and nontoxic. Such a switchable and multifunctional coating with whole lifecycle environmental-friendliness exhibits huge application potential.

Thermal stimulated structural transformation of cubic Zn0.78Cd0.22S nanoparticles to ZnO nano-hexagons: Tailoring of optical band gap and emission spectra for optoelectronic implementations

Ternary alloys of Zn0.78Cd0.22S nanoparticles (NPs) are synthesized via the facile co-precipitation technique. The as-synthesized sample exhibits a zincblende-type cubic phase with an average crystalline size of 2 nm. Thermal annealing and UV irradiation are utilized as post-treatment processes for tailoring the optical properties of Zn0.78Cd0.22S NPs. The as-synthesized sample exhibits a stable cubic phase up to 400 °C, during which partial phase transformation to a hexagonal structure is observed at a higher temperature of 500 °C. The oxidation of Zn0.78Cd0.22S NPs to mixed oxide phases with the majority of ZnO begins at 600 °C which induces morphology transformation to a relatively large nano-hexagon with a single crystalline domain size. The increase of the annealing temperature is accompanied by a decrease of Zn0.78Cd0.22S NPs optical band gap (Eg) due to the weakness of size confinement as well as the formation of localized states below the mobility band edges. The brief UV irradiation results in the increase of Eg whereas a further increase in exposure time is accompanied by a reduction of Eg. The photoluminescence (PL) spectrum of the as-synthesized sample covers a wide spectral range from UV to visible. Thermal annealing has a slight effect on the PL emission at high excitation energy, whereas low excitation energy reveals higher sensitivity to deep-state emission. Thermal oxidation incorporates a high concentration of oxygen-related defects that induce strong enhancement in the green emission at the expense of UV emission. This indicates the thermal-induced bleaching of shallow trapping sites and the evolution of other deep trapping or recombination sites.

Life after Ayahuasca: A Qualitative Analysis of the Psychedelic Integration Experiences of 1630 Ayahuasca Drinkers from a Global Survey

Ayahuasca is an Amazonian psychoactive plant medicine being explored for its potential therapeutic uses in Western contexts. Preliminary studies link ayahuasca use with improvements across a range of mental health indicators, but studies have not yet explored qualitative aspects of the post-treatment process known in the psychedelic literature as “integration”. This includes how participants make sense of their ayahuasca experiences and minimise harm/maximise benefits after ayahuasca use. A global online survey, conducted between 2017 and 2019, collected responses from 1630 ayahuasca drinkers (50.4% male, mean age = 43 years) to an open-ended question about their integration experiences after consuming ayahuasca. Inductive codebook thematic analysis was used to identify themes in participants’ integration experiences. Participants described integration experiences in three main ways. First, was an overall appraisal of the integration experience (e.g., as easy, challenging, or long-term/ongoing). Second, was describing beneficial tools which facilitated integration (e.g., connecting with a like-minded community and ongoing practice of yoga, meditation, journaling, etc.). Third, was describing integration challenges (e.g., feeling disconnected, going back to “old life” with new understandings, etc.). These findings suggest that integrating ayahuasca experiences can be challenging and take considerable time, though working through integration challenges may facilitate positive growth. Findings also challenge the role of individual psychotherapy as the primary integration tool in Western psychedelic therapy, suggesting that communal and somatic elements may also be useful. An expanded definition of psychedelic integration is proposed which includes working with integration challenges and adjusting to life changes.

Optimizing the Neural Network Architecture for Automation of the Tailored UV Post-Treatment of Photopolymer Printing Plates

In this work, three types of photopolymer printing plates for packaging printing were subjected to varied UV (ultraviolet radiation) post-treatments, and their surface free energy (SFE) components were calculated. SFE of the photopolymer printing plate is crucial in the process of transferring the ink from the printing plate to the substrate. Calculated polar and dispersive SFE components were used to build and optimize artificial neural networks for the prediction of the surface properties of different photopolymer materials after the performed UVA and UVC post-treatments. In this way, the production of printing plates with tailored SFE components could be automated and optimized. Consequently, products with improved qualitative properties could be printed. Results of the research have shown that the choice of the neural network’s activation function is most significant for the minimization of the mean squared error (MSE), while the number of neurons and hidden layers in neural networks has less influence on MSE. The optimized neural networks applied for common photopolymer materials in this work have the potential to be applied for the automation of the printing plates’ post-treatment process and the production of printing plates with surface properties tailored to specific printing systems.

Explosion effect directly induced hierarchical carbon nanotube electrocatalyst integrated with Fe/Co dual sites for hydrogen fuel cells

Atomically dispersed metal-site catalysts, especially those derived from high temperature calcination of zeolite-based imidazole salt framework (ZIFs), have great potential in catalyzing oxygen reduction reaction (ORR) with slow kinetics owing to their large atomic utilization and tunable coordination environment. However, ZIFs-derived carbon-based catalysts often exhibit octahedral particle morphology and thus complex post-treatment processes were usually required to modulate the pore structure of the membrane electrodes to enhance the utilization of metal-site sites in the cathode ORR of fuel cells. Herein, a highly efficient catalyst with Fe/Co dual metal sites anchored onto N-doped carbon nanotubes (CNTs) was synthesized by one-step calcination based on the explosion effect of ClO4- ion and Fe-Co bimetal coordination interaction, named FeCo-N-CNT. The introduction of ClO4- ions and Fe/Co bimetals gives the catalyst a dense reachable active site and a hierarchical porous structure. It is worth noting that the half-wave potential of the FeCo-N-CNT reached 0.9 V in an alkaline medium and showed good cyclic stability. More impressively, the FeCo-N-CNT also shows excellent ORR catalytic performance in both acid and neutral electrolytes, with a maximum power density 1.2 and 1.4 times higher than Fe-N-PC and Co-N-PC with single-metal sites in hydrogen fuel cells, respectively. This work provides a novel method for adjusting the structure of catalysts and improving the accessibility of metal-sites.