Feedstock Gas Research Articles

Carbon-negative production of acetone and isopropanol by gas fermentation at industrial pilot scale.

Many industrial chemicals that are produced from fossil resources could be manufactured more sustainably through fermentation. Here we describe the development of a carbon-negative fermentation route to producing the industrially important chemicals acetone and isopropanol from abundant, low-cost waste gas feedstocks, such as industrial emissions and syngas. Using a combinatorial pathway library approach, we first mined a historical industrial strain collection for superior enzymes that we used to engineer the autotrophic acetogen Clostridium autoethanogenum. Next, we used omics analysis, kinetic modeling and cell-free prototyping to optimize flux. Finally, we scaled-up our optimized strains for continuous production at rates of up to ~3 g/L/h and ~90% selectivity. Life cycle analysis confirmed a negative carbon footprint for the products. Unlike traditional production processes, which result in release of greenhouse gases, our process fixes carbon. These results show that engineered acetogens enable sustainable, high-efficiency, high-selectivity chemicals production. We expect that our approach can be readily adapted to a wide range of commodity chemicals.

Co-gasification of biomass and coal in a top-lit updraft fixed bed gasifier: Syngas composition and its interchangeability with natural gas for combustion applications

The co-gasification of biomass and coal is a promising approach for efficiently integrating the unique advantages of different gasification feedstock with syngas production. Additionally, syngas from the co-gasification of locally available biomass and coal could supplement the natural gas used in household and industrial burners. The top-lit updraft gasifier features a moving ignition front that starts at the top and propagates downward through the solids bed, while air enters from the bottom and the gas product flows upwards. This study assesses the co-gasification performance of palm kernel shell and high-volatile bituminous coal in a top-lit updraft fixed bed gasifier using 70, 85, and 100 vol% biomass and equivalence ratios ranging from 0.26 to 0.34. The results indicate that the ignition front propagates faster and is more uniform as the biomass volume increases. Micro GC analysis revealed that the H2/CO ratio remained in the range of 0.57–0.59, 0.49–0.51, and 0.42–0.46 for experiments with 70, 85, and 100 vol% biomass, respectively. A gas interchangeability analysis showed that syngas-natural gas blends with up to 15 vol% of syngas could combust in atmospheric natural gas burners without modifications. Thus, the top-lit updraft gasifier shows excellent potential for the co-gasification of coal and biomass. Further research on this technology should explore steam as a gasification agent to enhance the syngas energy content and continuous solids feeding.

H2 competition between homoacetogenic bacteria and methanogenic archaea during biomethanation from a combined experimental-modelling approach

Competition for H2 between homoacetogenic bacteria and methanogenic archaea is commonly faced in biological biogas upgrading process reducing the potential for high methane production capacities. In the present work, different feeding regimes were examined using anaerobic inocula that were adapted and non-adapted to the gaseous feedstock. Adapted inoculum could compensate the increased pressure at all examined levels and especially, produced above 95% of the theoretical methane without accumulating acetate at 0.2 atm. On the contrary, acetate accumulation was detected when a non-adapted inoculum was used. Microbial adaptation to elevated pressures can be applied as a means to improve production capacities. Thermodynamic analysis showed that hydrogenotrophic methanogenesis had always lower permissive H2 partial pressures (0.43–0.85 Pa) compared to homoacetogenesis (3.20–7.46 Pa) at the examined pH (neutral vs alkaline) and pressure levels (i.e., 0.2–2.0 atm). An unstructured kinetic model was developed to study the influence of the examined variables in the hydrogenotrophic, homoacetogenesis and aceticlastic pathways. The kinetic parameters of the proposed model were estimated from experimental results and the goodness of the fitting was assessed by the coefficient of determination which indicated that the model describes efficiently the dynamics of the different compounds involved in the investigated pathways.

Utilization of Spiked Pepper (Piper aduncum L.) as Feedstock for Gasification

The massive spread and growth of invasive alien plant species (IAPS) such as Piper aduncum L. (PA) endanger the natural ecosystem. Utilizing their woody biomass as feedstock through gasification to produce renewable energy can reduce risk and provide better incentives to rural communities. Heating value (HV), fixed carbon (FC), volatile combustible matter (VCM), and ash content were used to compare PA with five other tree species – namely, Calliandra calothyrsus L. (CC), Gliricidium sepium L. (GS), Broussonetia papyrifera L. (BP), Eucalyptus marginata L. (EM), and Eucalyptus urophylla L. (EU) – as fuel for gasification. The effects of particle size (ps), air volumetric flow rate (υair), and carbonization and their interactions to cold gas efficiency (CGE), producer gas flow rate (υsyngas), and specific gasification rate (SGR) were also studied. The economics and environmental impact of spiked pepper as feedstock were evaluated by hypothetically putting up a 100 kWe gasification plant in the Upper Bauyan Watershed serving 138 households. With an electrical efficiency of 17.1%, the plant would need 990 tons of PA. Feedstock supply would be adequate even after 20 yr of operation since biomass growth rate would be faster than consumption rate. The computed carbon dioxide (CO2) emissions annually for harvesting was 9.72 tons (shelterwood method) – 781.11 tons for gasification and electrical production against direct combustion, which theoretically emits 1,729.73 tons annually. Financial analysis indicated a profitable investment with a positive net present value of PHP 6,240,257.08 or USD 122,358 (USD 1 = PHP 51), IRR of 12%, payback period of 6.97 yr, and levelized cost of electricity (LCOE) of PHP 8.90 (USD 0.17). Overall, the study indicates the economic feasibility and ecological soundness of utilizing PA as feedstock provided that silvicultural management is applied in replanting indigenous trees in eradicated lands. This method can also be effective in restoring the landscape of affected watersheds.

Decarbonizing ethanol production via gas fermentation: Impact of the CO/H2/CO2 mix source on greenhouse gas emissions and production costs

This study explores key success factors for ethanol production via fermentation of gas streams, by assessing the effects of eight process variables driving the fermentation performance on the production costs and greenhouse gas emissions. Three fermentation feedstocks are assessed: off-gases from the steel industry, lignocellulosic biomass-derived syngas and a mixture of H2 and CO2. The analysis is done through a sequence of (i) sensitivity analyses based on stochastic simulations and (ii) multi-objective optimizations. In economic terms, the use of steel off-gas leads to the best performance and the highest robustness to low mass transfer coefficients, low microbial tolerance to ethanol, acetic-acid co-production and to dilution of the gas feed with CO2, due to the relatively high temperature at which the gas feedstock is available. The ethanol produced from the three feedstocks lead to lower greenhouse gas emissions than fossil-based gasoline and compete with first and second generation ethanol.

Assessment of a novel coupling integrated process for coproducing syngas and hydrogen from natural gas and biomass feedstocks with in-situ CO2 utilization

Over the past decade, extraordinary sets of chemical looping process concepts have been introduced based on the need to develop clean and efficient energy systems. Herein, a new integrated coupled process based on chemical looping technology for the coproduction of hydrogen and synthesis gas for multi-purpose goals has been proposed and investigated deeply. The proposed novel process is a dual-purpose integrated zero-emission reforming (DPIZER) process with multifunctionality and zero greenhouse gas emission. Also, energy and exergy analysis were performed on the newly designed unit. In addition, the obtained simulation data were validated with experimental tests. The synthesized 10-30wt.%NiO/Al2O3 oxygen carrier was investigated using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques and evaluated in chemical looping reforming (CLR) and sorption enhanced chemical looping reforming (SECLR) processes. The obtained results revealed that the efficiency of the novel process proposed in this study showed a great improvement than industrial conventional reforming process. The obtained experimental results revealed the highest methane conversion of about 100% and 90% at 750 °C in CLR and SECLR reactors, respectively. The simulation results revealed the production of highly pure hydrogen (H2/CO = 292), syngas (H2/CO ≈ 1), and ultra-pure hydrogen (H2/CO = 34,833) in three distinct reactors. In general, the process includes the production of ultrapure hydrogen without producing any pollutants such as CO2 and harmful gases from methane feed and biomass.

Electron transfer from Geobacter sulfurreducens to mixed methanogens improved methane production with feedstock gases of H2 and CO2

In order to solve problems of poor utilization of H2 and CO2 in biomethane conversion with mixed methanogens due to multi-channel competition and nondirectional electron transfer, Geobacter sulfurreducens were cocultured with mixed methanogens to promote oriented metabolic pathway of H2 and CO2 to produce CH4. When inoculation volume ratio of G. sulfurreducens to mixed methanogens was 2:4, CH4 yield increased to 0.24 mL/ml H2 (close to the maximum theoretical yield of 0.25 mL/ml H2) and conversion efficiency of H2 to CH4 increased from 72 to 96%. Electrochemical detection and three-dimensional fluorescence spectra showed that the co-culture system had an increased metabolic capacity and spectral intensity of fulvic acid-like compounds was enhanced, which mediated direct interspecific electron transfer to produce CH4. The 16S rRNA gene sequencing showed that relative abundance of G. sulfurreducens and Methanoculleus increased, indicating an established syntrophic relationship between G. sulfurreducens and Methanoculleus.

Methods for Producing Hydrogen-Rich Syngas in MSW Gasification

Although municipal solid waste (MSW) is a concern in many countries, it may be a highly appealing alternative feedstock for gasification to create sustainable gas fuels. The creation of hydrogen syngas from MSW gasification has received a lot of attention. The employment of a catalyst in the MSW gasification process is known to boost the gasification reactor's performance in producing hydrogen-rich syngas. Furthermore, the co-gasification approach is frequently utilized to increase syngas quality and gasification efficiency. This paper discusses many ways for gasifying MSW for the generation of hydrogen rich syngas. Catalytic gasification, co-gasification, and a modified gasification system are the gasification methods under consideration.

Investigation on gasification of coffee husk inCO2,H2O, and mixed atmospheres

AbstractCoffee husk, a residue from coffee production, could become a potential feedstock for gasification if a comprehensive engineering profile of this feedstock is well established. This study focused on investigating the coffee husk characteristics and its behaviors during pyrolysis and gasification. The proximate analysis results showed that coffee husk had a high volatile matter of 69.8 %. However, the high ash content (9.2 %) should be considered due to its negative contribution to the system. The higher heating value (HHV) of coffee husk was 18.3 MJkg‐1, comparable with woody biomass. The TGA‐ DTG results showed that the degradation of coffee husk began at 245oC and achieved the maximum weight loss rate (Rmax= 0.4 %oC‐1) at 310oC. Coffee husk char gasification under 20 % H2O (in N2) was about 2 times faster than under 20 % CO2(in N2), quite similar to wood gasification. In particular, an inhibitory effect between CO2and H2O on reactivity during gasification in the mixed atmosphere was observed. Database and results from this study would provide useful information for the design or modeling of an efficient coffee husk gasifier.

Chitosan/oleamide nanofluid as a significant medium for enhancing gas utilization efficiency in C1-gas microbial biotransformation

Microbial biotransformation of C1 gas feedstocks such as CH4 and CO is a notable technique for sustainable, carbon–neutral chemical and fuel production. However, low C1-gas utilization efficiency in biological processes has hampered the efficient production of value-added materials, despite efficient, nonnative strains having been recently developed. Here, we constructed a nanofluid material mainly composed of chitosan and oleamide (CS/OA), which was stably suspended with a particle size of 120.7 ± 39.0 nm in aqueous culture media below pH 7.5 and attached to the cell surface, leading to a change in hydrodynamic properties mainly due to the decrease of surface tension and a decrease in mass-transfer resistance on the cell surface. The nanofluid was applied to three C1-gas-utilizing strains, Methylomonas sp. DH-1 (a type I methanotroph), Methylosinus trichosporium OB3b (a type II methanotroph), and Thermococcus onnurineus NA1 156 T (a hyperthermophilic CO-utilizing archaeon). Changes in culture media and cell membranes from the applied CS/OA nanoparticles increased specific cell growth rates (μmax). Remarkably, the strains adapted from the seed culture using the CS/OA nanofluid media also had increased μmax in a subsequent subculture and the main culture using conventional culture media, resulting in higher C1 gas consumption, cell growth, and metabolite production, such as succinate production. These results showed that the CS/OA nanofluid could be an effective medium to increase gas utilization efficiency and cell growth, and it is expected that the nanofluid can be widely used for increasing the production of value-added metabolites in C1-gas microbial biotransformation.

Synergistic effect of freeze-drying and promoters on the catalytic performance of Ni/MgAl layered double hydroxide

Methane dry reforming is a potentially useful reaction but possesses some disadvantages such as catalyst deactivation by coking. Some new freeze-dried promoted-Ni/MgAl catalysts were used in this work for solving this drawback. The synergic effect of the freeze-drying method and incorporation of promoters was studied on physicochemical features of catalysts and catalytic performance. Field emission scanning electron microscopy images (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) revealed that the Sr-promoted Ni/MgAl catalyst had a scaffold structure with desirable pores in contact with feedstock gases. The temperature-programmed reduction (H2-TPR) and temperature-programmed deposition (CO2-TPD) techniques confirmed that the reduction behavior and basicity of the catalysts are affected by the type of promoter. In comparison to Y and Sr-promoted catalysts, the Sr-Ni/MgAl catalyst with the lower reduction temperatures, smaller Ni crystallite size, greater Ni dispersion, and higher basicity had the highest catalyst activity (72% CH4 conversion) and stability after 20 h time on stream without any carbon deposition. The higher basic cites resulted in eliminating coke specimens from the catalyst surface.

Integrated torrefaction-extrusion system for solid fuel pellet production from mixed fiber-plastic wastes: Techno-economic analysis and life cycle assessment

The world is witnessing an unprecedented generation and accumulation of fiber-plastic wastes resulting in various challenges due to inconsistency, waste-stream heterogeneity, conveying issues, self-heating, and difficulty in pelletization. This study presents a novel pilot-scale system that integrates torrefaction and extrusion to convert mix fiber-plastic waste into fuel pellets. The produced pellets have low cost, high heating value, better uniformity, and low environmental impact. They can be used as solid fuels or as feedstock for pyrolysis and gasification. To evaluate the pellet cost and its environmental impact, we performed Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA). The TEA integrates research findings from the torrefaction-extrusion project with the techno-economic models and estimates the costs, energy consumption, and mass balances for pelletizing and torrefaction. The analysis indicates that the baseline cost of producing uniform pellets is about $55.28/dry tonne (2020$). LCA results indicate that the torrefied product has cradle-to-gate embodied greenhouse gas emissions that are net negative, although they are higher than a comparable forest-derived woodchip product. Fossil energy demand for the torrefied product is lower than the forest-derived chip, indicating the torrefied product has strong potential for use as an environmentally beneficial feedstock for future processing.

Investigation into the catalytic gasification of coal gasification fine slag residual carbon by the leachate of biomass waste: Gasification reactivity, structural evolution and kinetics analysis

In this study, the applicability of chicken manure leachate (CML) to catalytic gasification of coal gasification fine slag residue carbon (RC) was investigated in order to guide the large-scale application of RC as a potential gasification feedstock. Firstly, the effects of different CML loading amount and gasification temperature on RC reactivity were investigated. The structural evolution of RC loaded with CML in gasification was deeply analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and in-situ high temperature stage coupled with optical microscope system (HSOM). The results showed that CML is rich in water-soluble alkali and alkaline earth metallic species, especially potassium, which can significantly improve the gasification reactivity of RC. The gasification activity increased with the increase loading amount of CML, but higher gasification temperature will weaken the catalytic ability of CML. The model free method can well predict the kinetics of RC gasification reaction. The existence of CML reduced the activation energy of gasification obviously. The activation energy of RC20CML was 100.96 kJ/mol, which was 37.81 kJ/mol lower than that of RC. Furthermore, the surface complexes produced during RC gasification were determined by temperature programmed desorption (TPD) technique. The results showed that CML loaded RC released more CO during TPD process, which indicated that CML promoted the formation of more active sites on the RC surface, thus accelerating the gasification reaction. This work will contribute to the classification and resource utilization of coal gasification fine slag.

Study on the corrosion of refractory materials by coal blended with the extraction residue of direct coal liquefaction in a simulated gasification atmosphere

Abstract Utilizing the extraction residue (ER) of direct coal liquefaction residue as a gasification feedstock has significant economic value. But the characteristic of high ash and iron in the ER would increase the risk of corrosion of the refractory materials and affect the long-term operation of the gasifier. In this work, corrosion experiments of molten slag derived from a mixture of 20 wt% ER and 80 wt% coal on a high-chromia refractory brick and SiC brick were carried out using a rotary-drum furnace in a simulated gasification atmosphere. The experimental results show that the viscosity of the poured slag is larger as compared to the initial ash sample at the same temperature, which suggests that the viscosity–temperature relationship of the poured slag should be used as the reference for the operation temperature of the gasifier to ensure that the slag can flow during operation. For a high-chromia refractory brick, iron oxides in molten slag could react with Cr2O3 in the refractory matrix but, because the aggregate was not found to be damaged, the damage to the matrix structure was the key factor for causing the corrosion of the high-chromia refractory brick. Metallic iron was observed in the exposed SiC brick, which indicated that the reaction between the iron oxides in the slag and SiC occurred, forming metallic iron and SiO2. The corrosion of a SiC brick by molten slag depended mainly on the dissolution of Al2O3 particles and the reaction between iron oxides in the molten slag and SiC particles. Therefore, the high iron content in coal ash had a serious influence on the corrosion of refractory materials. More efforts need to be made on coal blended with ER as a gasification feedstock in the future.

Catalytic performance of Co, Fe on MCM-41 synthesized from illite waste for gasification of torrefied cassava rhizome

The catalytic gasification of torrefied cassava rhizome (TCR) with metals (Co, Fe) on MCM-41 was studied throughout this work. The focus of this research is to synthesize, evaluate and analyze the performance of ordered mesoporous MCM-41 employing illite clay waste as silica and aluminum sources under hydrothermal pressure condition using cetyltrimethylammonium bromide as structure template. The characterization of catalysts was carried out by low angle X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and N2 physisorption isotherm which indicated the formation of well-ordered MCM-41 mesoporous materials, high surface area (952 m2/g) and corresponds to a type IV isotherm of hysteresis loop, respectively. Co and Fe were deposited on synthesized MCM-41 surface by impregnation method. The catalytic performance was tested in an ex-situ gasification process at 700 °C. The 5Co/MCM-41 catalyst significantly increased the carbon conversion from 68.63% to 77.30% while using 5Fe/MCM-41 catalyst yielded the highest H2/CO ratio of 0.66, hydrogen conversion of 26.80% and gas heating value of 10.72 MJ/kg. The results indicated that the illite waste may be converted to high-value zeolite material while TCR is a potential greener fuel feedstock for gasification. This novel method to synthesize the MCM-41 from illite clay waste utilized doping of cobalt and iron metal catalyst to increase the efficiency of gasification of TCR.

(Invited) Controlled Synthesis of Functional Carbon Nanomaterials By Gas-Liquid Interface Plasma

Carbon nanomaterials, such as fullerene, carbon nanotubes (CNT), graphene sheets, and so forth, play indispensable roles in nanotechnology research. Due to their unique self-organized nanostructure and unique physical and electrical properties, various types of applications using them are expected and have been developed. One of recent hottest topics among them is graphene sheets and their electric device applications. High quality graphene sheets for such the device applications, epitaxial growth or chemical vapor deposition (CVD) methods at high temperature up to 1,000°C, are used as a synthesis method in general. On the other hand, some kinds of applications, such as sensors, batteries, additives to polymers, and so forth, need a large amount of nanographene power. For that purpose, a reduction of graphene oxide (GO) is well known, but the quality of the synthesized graphene is not high enough. Recently, we have established a high-speed synthesis method of nanographene materials with high crystallinity by a plasma discharge at gas-liquid interfaces with alcohol sources. Y this method, a synthesis rate of nanographene over 1 mg/min and higher crystallinity of nanographene than the reduced GO have been realized. On the other hand, there is a trade-of relationship between the synthesis rate and crystallinity, when different types of alcohols were used as a feed stock gas. When ethanol,1-propanol, and 1-butanol were used, it was found that the higher synthesis rates were obtained by the higher-molecular weight alcohols, while its crystallinity was lower. This trade-of relationship is attributed to a ratio of carbon (C) and oxygen (O) atoms. O-related radicals (O, OH, etc.) in plasma could have etching effects of amorphous or low-crystallinity carbon components. Actually, according to the results of plasma diagnostic measurements and residual liquid analyses, it was found that crystallinity of nanographene materials degraded with decrease in OH intensity in plasma. Furthermore, small radicals such as C2 and CHx contribute to the synthesis of nanographene rather than by-products with a six-membered ring structure. After the synthesis, Pt nanoparticles were supported on their surfaces reducing the 8wt%-H2PtCl6 in H2O, and catalytic performances of Pt-supported nanographene were evaluated. In the cyclic voltammogram, nanographene materials synthesized using ethanol showed only about 10% degradation even after 10,000 cycles of the potential cycling test, although those using 1-butanol showed a drastic degradation. These results indicate that the higher-density Pt nanoparticles can be supported on the higher-crystallinity nanographene material and they show higher durability. Very recently, micrometer sized carbon nanosheets were synthesized using iron phthalocyanine or hemin with ethanol. And they showed excellent catalytic characteristics thorough 4-electron reduction pathway. According to the verification results of dependence on synthesis conditions such as the type of additive, such the catalytic activity is induced by pyridinic C-N bonds. These knowledges obtained in this study will open the way to the next-generation green energy solutions, such as high-performance catalytic electrode for the fuel cell.

Optimal design of large-scale solar-aided hydrogen production process via machine learning based optimisation framework

Hydrogen is an important energy carrier in the transportation sector and an essential industrial feedstock for petroleum refineries, methanol, and ammonia production. Renewable energy sources, especially solar energy have been investigated for large-scale hydrogen production in thermochemical, electrochemical, or photochemical manners due to considerable greenhouse gas emissions from the conventional steam reforming of natural gas and oil-based feedstock. The solar steam methane reforming using molten salt (SSMR-MS) is superior due to its unlimited operation hours and lower total annualized cost (TAC). In this work, we extend the existing optimisation framework for optimal design of SSMR-MS in which machine learning techniques are employed to describe the relationship between solar-related cost and molten salt heat duty and establish relationships of TAC, hydrogen production rate and molten salt heat duty with independent input variables in the whole flowsheet based on 18,619 sample points generated using the Latin hypercube sampling technique. A hybrid global optimisation algorithm is adopted to optimise the developed model and generate the optimal design, which is validated in SAM and Aspen Plus V8.8. The computational results demonstrate that a significant reduction in TAC by 14.9 % ~ 15.1 %, and CO2 emissions by 4.4 % ~ 5.2 % can be achieved compared to the existing SSMR-MS. The lowest Levelized cost of Hydrogen Production is 2.4 $ kg−1 which is reduced by around 17.2 % compared to the existing process with levelized cost of 2.9 $ kg−1.

Investigation on gasification of agricultural wastes: the case of macadamia husk

AbstractMacadamia husk, an overlooked residue of macadamia production, could become a promising feedstock for gasification with the help of extensive engineering knowledge. This study aimed at establishing a comprehensive database of the macadamia husk's characteristics as well as its behaviors during the whole gasification process. The results showed a high heating value of macadamia husk (17.47 MJ/kg) along with its low ash content (3.42 wt%), which is very suitable for thermo‐conversion processes. However, with a relatively high moisture content (15.72 wt%), macadamia husk might require additional pre‐treatment such as drying. The thermal decomposition of macadamia husk, determined through the TGA‐DTG technique, began at 220 °C and reached a maximum mass reduction rate (Rmax = 0.41 %/°C) at 295 °C. The gasification conversion rate was conducted under three distinctive atmospheres: carbon dioxide gasification (20 % CO2 in N2), steam gasification (20 % H2O in N2), and their mixed atmosphere were finished after 560, 495, and 395 s, respectively. The resulting database of this study would be of great use for the design, modeling as well as optimization of a macadamia husk gasifier.

Catalyst and process for the production of diesel fuel from natural gas, natural gas liquids, or other gaseous feedstocks

Doping non–metal atoms into transition metal oxides (TMO) is considered as an effective method to improve the catalytic performance of TMO. Nevertheless, it is actually not easy to achieve efficient non–metal doping in TMO. To address this issue, herein, we for the first time put forwards an oxygen vacancy (Vo) assisted doping strategy to achieve high non–metal atoms doping amount in TMO. Firstly, Vo is produced by simple acid etching treatment on pristine Co3O4, and then the obtained Vo decorated Co3O4 (Co3O4–Vo) is used as precursor to conduct P doping. By systematical characterizations and analysis, it is found that the as–formed Vo in Co3O4–Vo plays a role of doping sites, which bring about efficient P doping effect. Even at relatively low temperature, the as–prepared P–doped Co3O4–Vo (P–Co3O4–Vo) is evidenced to display a high P doping amount of 6.1 wt%, which is much higher than that (1.9 wt%) of directly P–doped Co3O4 (P–Co3O4). Consequently, P–doped Co3O4–Vo shows significantly enhanced activity towards oxygen evolution reaction (OER). Clearly, this work opens a new avenue to efficiently doping non–metal atoms into TMO.

Superior anti-corrosion performance on Cu substrate achieved by dense polypropylene coating with ultrahigh inhibition efficiency deposited via the environmental-friendly method

In this work, an environmental-friendly and one-step synthetic method are adopted for the protective coating for electronic devices. A polypropylene (PP-V) coating has been deposited on Cu substrate by plasma enhanced chemical vapor deposition (PECVD). Compared with the solvent-based methods, the PECVD method enables the transition from gaseous feedstock to solid coating, and the process does not involve polluting organic solvents. Moreover, the PP-V coating prepared by the PECVD method possesses an excellent protective effect, which is determined by the high denseness of the coating. PP-V coating delivers 99.96% ultra-high corrosion inhibition efficiency and can increase the low-frequency impedance modulus of the substrate by 3 orders of magnitude, while providing good protection after 24 h of saltwater immersion as well, which displays a good application prospect in the protection of electronic devices.