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Plasma methods are given significant attention in the context of conditioning the producer gas derived from biomass gasification. The goal of this work is to present the impact of hydrogen on the other producer gas compounds during microwave plasma valorization. These compounds include main producer gas components (CO, CO2, CH4, N2) and minor impurities (tar compounds, H2S and NH3). The results prove a beneficial impact of hydrogen addition on the conversion of CH4 and toluene, increasing it from ca. 68%–95% and ca. 97%–100%, respectively. Additionally, the presence of hydrogen changes the distribution of the products, inhibiting soot and aromatics production and promoting C2 compounds. In the case of CO2, the conversion increases from ca. 18%–63% when compared to nitrogen plasma, with CO being the resulting product. The presence of hydrogen inhibits H2S conversion and does not affect CO and NH3

In this research, a novel Ni-Co-metallic glass composite was fabricated and the effect of the co-deposition of Ni60Cr10Ta10P16B4 amorphous metallic glass powder (MGP) on the morphology and electrocatalytic properties of Ni–Co coatings was evaluated. The process was initiated by producing Ni60Cr10Ta10P16B4 via mechanical alloying of elemental powders using a planetary ball mill. Then, Ni–Co nanocomposite coatings were deposited on a copper substrate by the addition of different amounts of MGP via the electrodeposition method in a Watts bath. Then, the microstructure and chemical composition of the deposits were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) successively. The electrocatalytic performance of the coatings was evaluated in a methanol-containing alkaline (1 M NaOH) solution through cyclic voltammetry (CV). The enhancement of the electrocatalytic activity of Ni–Co coating through the co-deposition of MGP was observed. It was also concluded that the electrocatalytic properties of composite coatings are optimized when 7.5 g L−1 of MGP is added to the electroplating bath. Moreover, MGP was demonstrated to have altered the microstructure and the content of Co besides enhancing the roughness and specific surface of coatings.

Photocatalytic oxidation of toxic pollutants is a proficient technique to solve the problems associated with the treatment of bisphenol-A which is classified as 1B reprotoxic substance. In this paper, Ag2C2O4/Ag@GNS nanocomposite whereas Ag and graphene nanosheets (GNS) used as the charge carriers, which is combined through peroxymonosulfate (PMS) for the removal of bisphenol-A (BiP-A) for the first time. The XRD, UV-DRS, SEM, and TEM studies were performed to confirm the phase structure and the purity. Ag2C2O4/Ag@GNS nanocomposite exhibited superior photocatalytic performance and removal rate when compared with pure Ag2C2O4 and pure GNS. In Ag2C2O4/Ag@GNS photocatalyst, the deposited Ag on the surface of Ag2C2O4 rods effectively formed a metal and semiconductor heterostructure, thus photogenerated charge carriers were separated easily by the surface plasmon resonance effect (SPR) effect of noble Ag. Hence charge carriers lifetime has been extended to a great extent for the better photocatalytic performance. The experimental results confirmed that the O2−, OH, SO4− radicals were played major role in the photolysis process. Furthermore, the effect of the photocatalyst & PMS concentration, pH and co-existing ions towards the BiP-A degradation were studied in detail. According to the mass spectroscopy studies BiP-A pollutant was effectively deteriorated into smaller molecules and CO2, H2O. Furthermore, we have proposed the possible degradation pathway and photocatalytic mechanism for better understanding.

With the shortage of global fossil energy and the increasing crisis of environmental deterioration, hydrogen energy has become an environmentally benign alternative as a clean energy source. In most studies on photocatalytic hydrogen production, novel photocatalytic material has played an important role to enhance the hydrogen production rate. In this study, the optimal conditions for the synthesis of MoS2 were established through series of characterizations with 190 °C calcination temperature and 1 wt% PEG surfactant addition. The best conditions for synthesizing MOF include copper nitrate as the copper precursor, 30% ultrasonic amplitude, and 240 °C calcination temperature. After adding 1 wt% MOF in MOS2, a flower-like structure with small particle size, uniform distribution, regularity, and large surface pores, has been formed, where its unit is modified with many rough, porous, and high specific surface area octahedral structures. In addition, 1MOF/MOS2 has the most negative conduction band edge (−0.135 V), the smallest charge transfer resistance (Rct = 1.78 Ω), the largest photo current (11.1 mA/cm2), the lowest PL spectral peak intensity, and excellent photocatalytic stability. The above morphological features and optical properties can significantly form more active sites, enhance the electron transfer rate, and inhibit the electron-hole recombination, thus making the MOF/MOS2 composite photocatalyst achieve the maximum hydrogen production capacity (626.3 μmol g−1 h−1).

In this research, canola meal was densified using bio-additives including alkali lignin, glycerol, and l -proline. The fuel pellet's formulation was optimized. The best fuel pellet demonstrated relaxed density and mechanical durability of 1015 kg/m3 and 99.0%, respectively. Synchrotron-based computer tomography technique indicated that lack of water in pellet formulation resulted in a twofold increase in pellet porosity. Thermogravimetric analysis showed that ignition temperature (240 °C) and burn-out temperature (640 °C) for fuel pellet were smaller than those for coal. Impacts of process parameters were evaluated on the quality of the gas product obtained from pellet's steam gasification and hydrothermal gasification. The gasification experiments showed production of untreated syngas with a suitable range of H2/CO molar ratio (1.3–1.6) using steam gasification. Hydro-thermal gasification produced a larger molar ratio of H2/CO (1.8–51.2) for the gas product. Modeling of pellet's steam gasification showed an excellent agreement with experimental results of steam gasification.

Highly proficient, long-lasting non-noble-metal-supported electrocatalysts for hydrogen evolution reaction are important for hydrogen energy production through alkaline electrolyte. In transition metal dichalcogenides, tungsten sulfide is one of the popular materials and is used in a wide variety of applications. In this work, pristine and cationic surfactant assisted tungsten sulfide were successfully synthesized via simple hydrothermal method in alkaline electrolyte for hydrogen evolution reaction. X-ray diffraction confirmed tungsten sulfide rhombohedral structure formation with high index plane (003). Scanning electron microscopy explored tungsten sulfide nanosheet-assembled mesoporous sphere morphology. Tungsten sulfide and cationic surfactant assisted tungsten sulfide overpotential values were found to be 141 and 102 mV at 10 mA/cm2 from linear sweep voltammetry curves. The obtained Tafel slope of tungsten sulfide and cationic surfactant assisted tungsten sulfide were 26.9 and 21.4 mV/dec, respectively. The solution and charge transfer resistance of the prepared materials were obtained from Nyquist plot and found to be 1.7 and 1.4 Ω, and 53.6 and 32 Ω, respectively. The specific surface area, pore diameter, and volume were analyzed by Brunauer–Emmett–Teller method and obtained values for surface area, pore size, and volume of cetyltrimethylammonium bromide assisted tungsten sulfide were 65.05 m2/g, 3.502 nm, and 0.067 cc/g, respectively. The obtained result suggested that 0.1 M cationic surfactant assisted tungsten sulfide showed high catalytic activity with minimum overpotential. Long-term durability studies also suggested that the optimized surfactant-assisted tungsten sulfide had excellent stability over a prolong time of 16 h without any decay. However, the stability of the material exhibited only 90% retention which will improve in our near future works by using carbon-based materials. Hence, carbon-based materials exhibited outstanding chemical stability and offer large surface area, which significantly improves the hydrogen evolution reaction activity and suggests to be used in large-scale applications.

Hydrogen (H2) is the future energy carrier and it is quite challenging to produce at a large-scale on economic basis. The water splitting technique has achieved a good place in H2 production. To generate efficient electrocatalysts for the Hydrogen evolution reaction (HER), low-cost synthetic designs are necessary. In our study, a one-step co-precipitation reduction process was used to synthesize NiWS electrocatalyst. The crystalline structure, phase purity, elemental composition and the surface morphology of the as-prepared samples have been examined by different characterization techniques. These techniques have proved that the elemental presence and formation of NiWS with high crystalline nature (rhombohedral). Furthermore, the performance of the electrocatalyst towards HER has been evaluated through electrochemical methods. On analysis, NiWS/CNT showed an excellent electrochemical activity of 175 mV, and pure NiWS showed 201 mV at 10 mA/cm2 in an alkaline electrolyte. These over-potential values are lower than HER in acid and neutral electrolytes. Further, the as-prepared NiWS/CNT proved to be a highly stable and efficient platinum-free electrocatalyst for HER.

Recycling CO2 into light olefins is a promising approach to reduce CO2 emissions. To promote this technology, an efficient catalyst with high activity and selectivity towards light olefins is imperative. In this work, a series of Fe–Co–K supported on micro-mesoporous carbon (MMC) and microporous carbon (MC) with different metal loading contents (20–80 wt%) were prepared for CO2 hydrogenation to light olefins. Impregnating mixed metal oxides on both MMC and MC reduced particle sizes and enhanced their dispersion and reducibility, yielding a higher CO2 conversion compared to the unsupported Fe–Co–K catalyst. The metal oxides were highly dispersed inside the micropores of MC support, achieving the highest CO2 conversion. However, the high dispersion of metal oxides inside micropores led to the formation of isolated particles with a low interfacial contact with each other, resulting in a low light olefins selectivity. The MMC support provided a lower degree of metal dispersion, creating more interfacial contact area, promoting the selectivity towards olefins. Overall, the 60 wt% Fe–Co–K supported on MMC catalyst exhibited the highest light olefins yield of 10.8% at 400 °C and 20 bar and excellent stability.

Using first-principles calculations, we investigate the hydrogen evolution reaction (HER) on the noble-metal-nanoparticle-coated zinc or zinc-tin oxide surfaces. Among the six catalytic structures, the adsorption free energy of Au/ZnO structure is closest to zero. The relative energy diagrams reveal that Volmer-Heyrovsky mechanism on the NP (oxide) reactive site dominants the HER process on NP/ZTO (Pt/ZnO and Au/ZnO) structures. However, comparing the adsorption free energy and primary energy barrier of the prefer path of each structure, the Pt/ZnO structure shows the best performance for the HER process.

Narrow-band-gap LaFeO3 (approximately 2.1 eV) has good thermal stability, and applications for light-driven water splitting. Thus, heterojunction catalyst containing LaFeO3 and Au nanoparticles (NPs) are investigated for photoelectrochemical hydrogen production. The use of a citric acid or KOH modifier and calcination yields different LaFeO3 particle morphologies and phases (La(OH)3 alone or La(OH)3 and La2O3, respectively), which affect the Au NPs coverage ratio. In addition, the formation of a heterojunction, the surface-plasma resonances (SPRs) effect, and the unique nanospikes on the Au NPs, red-shift happens in the light wavelength and reduce the photonic extinction to less than 2.1 eV. Further, in ethanol and l-butanol under AM 1.5G irradiation, more hydrogen is generated in the former than the latter at all tested temperatures. In addition, the activation energy for the formation of hydrogen is lower in ethanol than in 1-butanol. Finally, an amorphous structure is beneficial for photocatalysis.

Slow kinetics and emotive design of electrocatalysts are the main barriers to effective oxygen evolution and hydrogen production from water. To overcome these challenges, nickel sulfide impregnated electrocatalysts with auxiliary structural features have recently attracted attention as effective alternatives for the oxygen evolution reaction (OER). Herein, nickel sulfide (NiS) nanowires are developed directly on nickel foam (NF), which have proven to be a highly efficient electrocatalyst for OER in an alkaline medium. For this, NiS nanowires were grown on NF for short intervals of 30, 60, 90 and 120 min through an aerosol-assisted chemical vapor deposition (AACVD) process using nickel diethyldithiocarbamate as a precursor. The as-developed NiS electrode showed excellent OER activity in 1.0 M KOH solution. It is noteworthy that the NiS electrode produced after 90 min provides a reference current density of 10 mA cm−2 at an overpotential (η) of 210 mV and achieves a higher current density of 500 mA cm−2 at an overpotential of 340 mV. Moreover, the nanocatalyst has observed a low Tafel value (60 mV dec−1) and good OER stability. After the electrolysis, it was found that the surface of the NiS catalyst was partially modified into nickel oxide. The S atom in the NiS catalyst can provide an activator function that first converts the sulfide to a hydroxide and then eventually becomes an oxyhydroxide species. The more active nickel hydroxide/oxyhydroxide phase raises the water oxidation performance to a new level. The facile synthesis of NiS nanowire films by AACVD tends to be used as an anodic material in various other power generation and energy conversion devices such as batteries, fuel cells, and supercapacitors.

Solar energy is one of the elements that have been used as a resource in the green energy field. Hydrogen, as an energy carrier, can be produced from many kinds of sources, including solar energy. Here, we present two-dimensional (2D)perovskite material derived from the Dion-Jacobson phase (DJ), Ca2Nan-3NbnO3n+1- (CNNO−) nanosheets, with the number of layer n = 4–6 synthesized via microwave-assisted hydrothermal method. The starting material KCa2Nb3O10 (KCNO) is made from two methods. The solid-state calcination KCNO product has more than two-phase, while the molten-salt synthesis produces a well cubic KCNO crystalline. TThe thickness of the 2D CNNO− nanosheets is increasing, in dependence on the n value. Meanwhile, the estimated optical band gap is decreasing, in dependence on the n value. 2D CNNO− nanosheets show the absorbance under ultraviolet (UV) light, which confirms their semiconducting nature. The capability of these 2D nanosheets to generate hydrogen is presented via photo-electrochemical (PEC) water splitting. The molten-salt fabricated CNNO− nanosheets CNNO6 shows better performance with the highest efficiency ɳ up to 0.110% when applied to the PEC device.

An ongoing challenge still lies in the exploration of proficient electrocatalysts from earth-abundant non-precious metals instead of noble metal-based catalysts for clean hydrogen energy through large-Scale electrochemical water splitting. However, developing a non-precious transition metals based, stable electrocatalyst for cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) is important challenge for modern energy conversion technology. In this report Vanadium doped bimetallic nickel-iron nanoarray, fabricated by carbon supported architecture through carbonization process for electrochemical water splitting. Three types of catalysts were prepared in different molar ratio of Ni/Fe. The electrocatalytic performance demonstrated that the catalyst with equal mole ratio (0.06:0.06) of Ni/Fe possess high catalytic activity for both OER and HER in alkaline and acidic medium. Besides, our findings revealed that the doping of vanadium could play a strong synergetic effect with Ni/Fe, which provide a small overpotential of 90 mV and 210 mV at 10 mA cm−2 for HER and OER respectively compared to the other two catalyst counterparts. Also, the catalyst with 1:1 (Ni/Fe) molar ratio showed a high current density of 208 mA cm−2 for HER at 0.5 M H2SO4 and 579 mA cm−2 for OER at 1 M KOH solution, the both current densities are much higher than the other two catalysts (different Ni/Fe ratio). In addition, the presented catalysts showed extremely good durability, reflecting in more than 20 h of consistent Chronoamprometry study at fixed overpotential η = 250 mV without any visible voltage elevation. Similarly, the (Ni/Fe) equal ratio catalyst showed better corrosion potential 0.209 V vs Ag/AgCl and lower current density 0.594 × 10−12 A cm−2 in high alkaline medium. The V-doping, MOF/GO surface defects are significantly increased the corrosion potential of the V-NixFey-MOF/GO electrocatalyst. Besides, the water electrolyzed products were analysed by gas chromatography to get clear insights on the formed H2 and O2 products.

s Flower-like BiOI and Bi5O7I photocatalysts were synthesized by a microwave-assisted solvothermal process and then calcined at various temperatures. The effects of calcination temperature on the phase structure, crystal property, morphology, color, optical property, and activity of the photocatalysts were investigated. As the calcination temperature increased, a blue shift was observed in the diffuse reflection spectra and the band gap increased. After the calcination treatment at 500 °C, the XRD, Raman spectra, and TEM results confirmed that BiOI transformed to Bi5O7I. Although flower-like microspheres still existed, the shapes of building blocks changed from lamellar nanoplates to thick twisted stripes when the BiOI transformed to Bi5O7I. BiOI with a calcination treatment at 300 °C exhibits an improved H2 production activity of 1373 μmol g−1 h−1. The XRD spectra reveal that the B-400 photocatalyst was a Bi5O7I-rich and BiOI-deficient composite material. Fewer Bi5O7I–BiOI interfaces and lower light absorption may be the reasons why the B-400 photocatalyst with Bi5O7I–BiOI compositions did not exhibit higher activity than B-300 (pure BiOI) and B-500 (pure Bi5O7I) photocatalysts.

Using a newly developed two-step hydrothermal process, flowerlike Ce0.5Zr0.5O2 with an oxygen storage capacity (OSC) of 536 μmol O2 g−1, almost twice as high as that of pure flowerlike CeO2 (284 μmol O2 g−1), can be synthesized. The synthesized ceria-based oxide supports loaded with Ni are dispersed in a ceramic fiber network to form paper-structured catalysts (PSCs). Among the prepared PSCs, the PSC with the flowerlike Ce0.5Zr0.5O2 exhibits the highest catalytic performance for dry reforming of methane (DRM) at 750 °C with the initial methane conversion of 88.4%, degradation rate of 0.1% h−1 and amount of deposited carbon of 0.04 g per gram catalyst, whereas for the Ce0.5Zr0.5O2 synthesized by the one-step hydrothermal process, the values are 83.7%, 0.62% h−1 and 0.07 g per gram catalyst, respectively. This is attributed to the Ni anti-sintering on the petals of the flowerlike structure and the coking tolerance resulting from the high OSC.

Graphitic carbon nitride (g-C3N4) is considered a potential photoactive semiconductor for photocatalytic hydrogen evolution (PHE). Although being active in producing hydrogen, it is in general suffering from severe charge recombination rate, low mobility of charge and narrow visible light response range largely, which has restricted its greater application. Existing reviews on g-C3N4 are lacking of systematic and summative view on the effects of the physical-chemical structure-activity relationship between g-C3N4 and the modification involving phosphorus (P). Many studies indicate that adding P into g-C3N4 could effectively elevate the photo-activity. Underlying reasons for the observed improved photo-activity are discussed in this review. Here, P-containing g-C3N4 photocatalysts are grouped into the categories of P elemental doping, composite with elemental P, as well as the addition of metal phosphide as cocatalysts. These P-containing g-C3N4 possess novel properties demonstrating favorable photocatalytic activities as compared with the other elemental (such as O, S, B)-based materials. Therefore, in this mini review, we summarize and discuss the advances on the P-containing g-C3N4 photocatalysts, including the preparation strategies, physicochemical properties, the application for hydrogen production as well as the related reaction mechanism. Importantly, the physical-chemical structure-activity relationship between g-C3N4 and the integrated P is revealed. Finally, an overview of the current research status and challenges on future is presented, which would be helpful in designing and developing other P-containing photocatalysts for various photocatalytic applications.

Canola meal is a low-value agricultural residue obtained after oil extraction from canola, the utilization of which requires further attention. On the other hand, plastic waste disposal is also another leading issue that creates severe environmental challenges. Supercritical water gasification is considered an environmentally friendly technology to produce hydrogen from plastic residues and organic wastes. This study deals with hydrothermal co-gasification of canola meal and plastic wastes (i.e., low-density polyethylene) while exploring the influence of temperature (375–525°C), residence time (15–60 min) and plastic-to-biomass ratio (0:100, 20:80, 50:50, 80:20 and 100:0) on hydrogen yield. Maximum hydrogen yield (8.1 mmol/g) and total gas yield (17.9 mmol/g) were obtained at optimal temperature and residence time of 525°C and 60 min, respectively. A change in the gas yield with variable plastic-to-biomass ratio showed synergistic effects between both feedstocks. The trend of catalytic performance towards improving hydrogen yield was in the following order: WO3–TiO2 (18.5 mmol/g) > KOH (16.9 mmol/g) > TiO2 (9.5 mmol/g) > ZrO2 (7.8 mmol/g) > WO3–ZrO2 (7.4 mmol/g).

This study discusses the influence of fluidization and gasification parameters on the hydrogen composition in syngas. For gasification conditions, when Stage 1 and Stage 2 gasifier temperature is 900 °C, the hydrogen content in syngas is 35.59 mol.% when the activated carbon is used as bed material. For using zeolite as bed material, the hydrogen content is 38.25 mol.%. The hydrogen content is higher than that under other conditions, but if the Steam/Biomass ratio is increased to 0.6, the hydrogen content resulted from zeolite as bed material is the highest 39.38 mol.%. For fluidization parameters, when Stage 2 bed material size is changed to 0.46 mm, no matter the bed material is activated carbon or zeolite, the hydrogen content in syngas is the best among three particle sizes. In terms of operating gas velocity, when gas velocity is 1.5 Umf, the hydrogen content is higher. For fluidization parameters, the two bed materials can increase hydrogen content in syngas effectively in Stage 2 fluidized bed, and their effects are similar to each other. However, considering the fluidization parameters, the hydrogen content in syngas when activated carbon is used as bed material is better than that when the zeolite is used.

In a proton-exchange membrane water-electrolysis system, performance is greatly affected by the anode materials and operation modes. Moreover, high voltages allow greater hydrogen production as well as the potential of creating ozone for green disinfection. However, after switching off power and restarting, a big decrease in performance drop as well as hydrogen/ozone generation. In this study, different additives—multi-wall carbon nanotubes, surface-modification graphene, reduction graphene oxide, and graphene oxide—are adopted and mixed with PbO2 and to create anode catalyst ink. The characteristics of the anode catalysts are investigated with voltage-current test, interruptive power supply, electrochemical impedance spectroscopy and high voltage accelerating tests. The results show that the anode of MEA with additive, multi-wall carbon nanotubes or multi-wall carbon nanotubes plus surface-modification graphene, lead to twice higher performance. Further, anode of MEA with additive, multi-wall carbon nanotubes, multi-wall carbon nanotubes plus graphene oxide, and multi-wall carbon nanotubes plus reduction graphene oxide, displays better restoration (34–36%↓).

Hydrogen technology is widely considered a novel clean energy source, and electrolysis is an effective method for hydrogen evolution. Therefore, efficient hydrogen evolution reaction (HER) catalysts are urgently needed to replace precious metal catalysts and meet ecological and environmental protection standards. Herein, Ni–Mn–P electrocatalysts are synthesized using facile electrodeposition technology. The influence of the Mn addition on the catalytic behavior is studied by the comprehensive analysis of catalytic performance and morphology of the catalysts. Among them, the Ni–Mn–P0.01 catalyst exhibits small coral-like structures, greatly improving the adsorption and desorption of hydrogen ions and reducing the overpotential hydrogen evolution. Consequently, overpotential at 10 mA cm−2 electric current density is 113 mV, and the value of the Tafel slope achieves 74 mV/dec. Furthermore, the Ni–Mn–P catalyst shows long-time (20 h) stability at current densities of 10 and 60 mA/cm2. The results confirm that the synergistic effect of Ni, Mn, and P accelerates the electrochemical reaction. Meanwhile, the addition of manganese element can change the micromorphology of the catalyst, thereby exposing more active sites to participate in the reaction, enhancing water ionization, improving the catalytic performance. This study opens a new way toward improving the activity of the catalyst by adjusting Mn concentration during the electrodeposition process.

The development of low-temperature combustion models combined with the use of biofuels has been considered as an efficient strategy to reduce pollutant emissions like CO, HC. NOx, and smoke. Indeed, Homogeneous Charge Compression Ignition (HCCI) is the new approach to drastically minimize NOx emissions and smoke owing to the lower cylinder temperature and a higher rate of homogeneous A/F mixture as compared to compression ignition (CI) engines. The present research deal with the behavior analysis of a CI engine powered by diesel, Euglena Sanguinea (ES), and their blends (ES20D80, ES40D60, ES60D40, ES80D20). The experimental results revealed the highest brake thermal efficiency for ES20D80 although it decreased by 4.1% compared to diesel at normal mode. The average drop in HC, CO, and smoke was 2.1, 2.3, and 5.7% for ES20D80 as opposed to diesel fuel. Therefore, in the next stage, ES20D80 with various concentrations of graphite oxide (GO) nanoparticle (20, 40, 60, and 80 ppm) was chosen to carry out experiments in the HCCI mode, in which hydrogen gas was induced along with air through the intake pipe at a fixed flow rate of 3 lpm for the enrichment of the air-fuel mixture. As a result, the combination of hydrogen-enriched gas and GO-added ES20D80 in the HCCI mode showed similar performance to the CI engine but registered a major reduction of NOx and smoke emissions, corresponding to 75.24% and 53.07% respectively, as compared to diesel fuel at normal mode.

We report a unique composite of La0.4Sr0.4Ti0.9Ni0.1O3-δ (LSTN) nanoparticles interlaced with two dimensional Ti3C2Tx (MXene) nanosheets, providing high conductivity. LSTN heterostructure synthesized by the sol-gel method produces a large oxygen vacancy and creates a variable valence state while, MXene synthesized from Hydrofluoric acid (HF) treatment resulted in a highly hydrophilic and conductive surface, thereby enhancing the charge transferability. For OER, the LSTN/MXene 66.67% electrode exhibits a benchmark of 10 mA cm−2 at a potential of 1.56 (V vs RHE) in 1 M KOH. It has exhibited the lowest Tafel slope of 44 mV dec−1 and highest mass activity (60 mA g−1 @ 1.59 V) due to quicker ions diffusion and increased available exposed area. Moreover, the efficient LSTN/MXene 66.67% electrode showed good long-term durability during a 24 h stability test at a current density of 100 mA cm−2. The strong interfacial interaction and high charge transfer among LSTN nanoparticles and 2D MXene nanosheets not only provide good structural strength to the composite but also improves the redox activity of LSTN/MXene 66.67% catalyst towards OER. This work provides improved conductive properties of perovskite by developing a composite of perovskite and MXene, that has significantly enhanced electrochemical properties of the catalyst by undergoing fast kinetics.

Bimetallic PtPd nanowires are produced by the centrifugal electrospinning method and their application as electrocatalysts in the cathode of a proton exchange membrane fuel cell (PEMFC) is evaluated. The effects of system parameters on the morphology of PtPd nanowires after calcination are explored including the rotation speed of spinneret, applied electric field, and atomic ratio of Pt and Pd in the composition. Cyclic voltammetry tests are conducted to characterize the electrochemical property and the produced PtPd nanowires are employed to fabricate the cathode catalyst layer in a PEMFC. The cell performance is measured and compared with commercial Pt/C electrocatalysts. Results show that bimetallic PtPd nanowires can be produced successfully with minimum mean diameter of 79 ± 24 nm and maximum electrochemical active surface area (ECSA) of 10.29 m 2 g − 1 at the atomic ratio Pt:Pd = 3:1. By the accelerated degradation tests, the PtPd nanowires demonstrate better durability than Pt/C. The present results reveal that the centrifugal electrospinning method can successfully fabricate PtPd nanowires which have great potential to be utilized in PEMFCs.

This study analyzes the characteristic numerical analysis of membrane electrode assembly in Proton Exchange Membrane Fuel Cell (PEMFC) with bipolar plate, flow channel, gas diffusion electrode, and proton exchange membrane. The numerical solution focuses on discussing the effects of different parameters, including permeability, porosity, and operation voltage, on various mass fractions, current-voltage curve, and power-voltage curve. The results show that as the porous medium with high gas permeability is an important factor that affects the mass fraction of hydrogen. Regarding the analyses of various porosities, the fuel cell performance can be effectively promoted with larger ratio of porosity and permeability. However, increasing the porosity will affect the electrical conductivity and increase the flooding of water, which will block the flow channel and reduce efficiency.

Electrolysis of seawater gets an attention to produce hydrogen for renewable energy technology. It significantly reduces the use of fresh water instead of seawater. Development of low temperature fabrication of electrocatalyst can explore seawater splitting by avoiding chloride reduction during the hydrogen production. In the present work, we fabricated low temperature hydrothermal growth of Cu2S electrocatalyst on Ni foam at constant temperature of 80 °C at different growth times of 1–3 h. The prepared Cu2S electrocatalyst grown for 1 h exhibited low overpotentials of 76 and 118 mV at 10 mA/cm2 (289 and 358 mV overpotentials at 100 mA/cm2) in 1 M KOH deionized water and seawater, respectively for hydrogen evolution reaction (HER). The Tafel plot of Cu2S catalyst grown for 1 h showed lesser Tafel slope value of 128 mVdec−1 than that of other growth times 2 h (136 mVdec−1) and 3 h (142 mV dec−1) indicating elevated electrocatalytic behaviour of Cu2S grown for 1 h. Electrochemical impedance spectroscopy (EIS) showed charge transfer resistance of 12.8Ω, 19.6 Ω and 25.7Ω, for Cu2S grown for 1, 2 and 3 h, respectively, this lower charge transfer resistance indicated higher charge transfer properties. The Cu2S electrocatalyst grown for 1 h sustained retention of 80% after 12 h continuous stability test. Therefore, the cost-effective and low temperature fabrication of Cu2S electrocatalyst proceeds for development of largescale seawater splitting for hydrogen production.

Nowadays, electrochemical water splitting is a securing alternative for clean-energy production and also an efficient expertise for oxygen and hydrogen production. Compared to single metal-based electrocatalyst, multi metal-based electrocatalyst offers more active sites, high surface area, and distinctive nanostructure for effective water oxidation. In this work, nickel and cobalt co-doped MnCO3 was successfully synthesized via a facile co-precipitation technique. Rhombohedral crystal phase of MnCO3 nanostructures and its crystallite sizes were thoroughly analyzed by the XRD spectra. Incorporation of doping element such as Ni and Co in MnCO3 nanostructures exhibited two different morphologies which enhanced the catalytic performance of the prepared samples. Large surface area and porosity of the nanomaterials improved the stability and activity of the prepared MnCO3 nanostructures. EDX analysis confirmed Mn, C, O, Ni and Co elements in stoichometric ratio. Moreover, the specific capacitance of (Ni, Co) co-doped MnCO3 nanostructures attained 581 F/g while the other electrodes attained only 207, 332 and 175 F/g respectively. A small Tafel slope with low overpotential of Ni, Co co-doped MnCO3 nanostructures was 20.2 mV/dec and 293 mV respectively. Therefore, the prepared electrocatalysts of Ni, Co co-doped MnCO3 nanostructure is one of the attractive anode material for high performance energy conversion applications.

The process parameters for dry reforming of methane (DRM) over Ni–W/Al2O3–MgO catalyst are optimized using response surface methodology (RSM). The Ni–W bimetallic catalyst is synthesized by co-precipitation method followed by impregnation. The catalysts are characterized by BET, XRD, FESEM, EDX and TEM; to study physicochemical properties, morphology, composition, crystallite size and deposited carbon. The effect of process parameters, i.e., reaction temperature (600oC–800 °C) and feed gas ratio (0.5–1.5) on the CH4, CO2 conversions and syngas ratio are studied. A temperature of 777.29 °C with CH4: CO2 of 1.11 at GHSV of 36,000 cm3gm.cat−1h−1, delivered the CH4 and CO2 conversions of 87.6% and 93.3%, respectively along with H2:CO of 1. The predicted process parameters were verified through actual experimental analysis at the optimized conditions, and results agreed with CCD of the RSM model with insignificant error. The MWCNT formed during DRM avoided catalyst deactivation and delivered stable performance over 12 h of reaction test at the optimized conditions.

CO methanation has arisen as an attractive research area due to its ability to transform syngas into substituted natural gas. Current monometallic catalysts have a severe problem; quickly deactivated. It is generally known that by introducing another metal to create a bimetallic catalyst, synergistic interaction between both metals considerably enhances catalyst effectiveness. This paper provides a detailed overview of bimetallic catalysts for CO methanation, covering its synthesis method and effect on physicochemical characteristics. The bimetallic catalyst can both reinforce or weaken the metal-support and metal-metal interaction, which weakening it favors reducibility while reinforcing it favors stability. Particle size and dispersion also improve, whereas adding lanthanides can increases the basicity. We also present the mechanism of CO methanation over the bimetallic catalyst, which modifies the mechanism's energy and rate value. This review provides insights on how reaction effectiveness is enhanced, enabling catalyst development with the highest possible performance.

Silicon-based nanosheets (SNS) were synthesised via a mild (60 °C) and time-saving (8 h) modified topochemical method. Then, Cu3(BTC)2 and SNS@Cu3(BTC)2 were successfully synthesised by microwave irradiation, and their characteristics and hydrogen storage performance were analysed by multiple techniques. The accordion-like SNS exhibited void spaces, a unique low buckled structure, and ultrathin, almost transparent, loosely stacked layers with a high specific surface area (362 m2/g). After in-situ synthesis with Cu3(BTC)2, the SNS compound achieved a high specific surface area (1526 m2/g), outstanding hydrogen storage performance (5.6 wt%), and a desirable hydrogen diffusion coefficient (10−7). Thus, SNS doping improved the hydrogen storage performance of Cu3(BTC)2 by 64% through electron transfer reactions with Cu enabled by the unique composite nanostructure of SNS@Cu3(BTC)2. This study presents a promising method of synthesising SNS and porous composite materials for hydrogen storage.

Solar energy to hydrogen production is an effective way to solve the energy crisis. Here, we report a Ti3CN@TiO2/CdS photocatalyst with highly efficient photocatalytic performance. Ti3CN@TiO2 materials with nanoflower morphology or lamellar morphology were obtained from Ti3AlCN by controlling the etching time, and then loaded CdS nanoparticles to improve the photocatalytic efficiency. The physical and chemical properties of the catalyst were characterized by various characterization techniques. Ti3CN@TiO2/CdS photocatalyst shows an enhanced photocatalytic activity of 3393.4 μmol g−1h−1, much higher than that of CdS and Ti3CN@TiO2..

The exploitation of noble-metal-free photocatalysts with high solar-to-H2 conversion efficiency is a hot topic in the photocatalysis field. Molybdenum sulfide materials, which have good physicochemical properties and excellent hydrogen evolution activity, have become an effective noble metal cocatalyst substitute and attracted widespread attention. In this work, a highly efficient photocatalyst constructed by decorating thiomolybdate [Mo2S12]2- nanoclusters on TiO2 is reported for the first time. The resultant [Mo2S12]2-/TiO2 photocatalyst shows a remarkable enhanced hydrogen evolution rate under the Xenon light irradiation. At the optimal loading amount of [Mo2S12]2-, the photocatalyst exhibits a photocatalytic hydrogen evolution rate of 213.1 μmol h−1 g−1, which is about 51 times that of the pure TiO2. Characterization results show that the intimate contact between [Mo2S12]2- and TiO2 promotes the separation of hole-electron pairs, prolongs the lifetime of carriers, and thereby increases the photocatalytic activity. Furthermore, abundant bridging S in the [Mo2S12]2- acts as active sites for hydrogen evolution, which also contributes to the enhanced hydrogen production rate. This work demonstrates an efficient way for the construction of noble-metal-free hydrogen evolution photocatalyst and provides a useful reference for the development of low cost photocatalysts in the future.

Metal-organic frameworks (MOFs) are considered emerging materials as they further improve the various properties of polymer membranes used in energy applications, ranging from electrochemical storage and purification of hydrogen to proton exchange membrane fuel cells. Herein, we fabricate composite membranes consisting of polybenzimidazole (PBI) polymer as a matrix and MOFs as filler. Synthesis of ZIF-8 and UiO-66 MOFs are conducted through a typical solvothermal method, and composite membranes are fabricated with different MOF compositions (e.g., 2.5, 5.0, 7.5, and 10.0 wt %). We report a significant improvement in proton conductivity compared with the pristine PBI; for example, more than a three-fold increase in conductivity is observed when the PBI-UiO66 (10.0 wt %) and PBI-ZIF8 (10.0 wt %) membranes are tested at 160 °C. Proton conductivities of the composite membranes vary between 0.225 and 0.316 S cm−1 at 140 and 160 °C. For the comparison, pure PBI exhibits 0.060 S cm−1 at 140 °C and 0.083 S cm−1 at 160 °C. However, we also report a decrease in permeability and mechanical stability with the composite membranes.

In this work, vanadium and lanthanum co-doped ZnO/CNTs (VL-ZnO/CNTs) composites of large surface area and enhanced light assimilation range were produced for boosted hydrogen evolution from water. The photocatalysts were investigated for their morphological, structural, optical and photocatalytical properties. The photocatalytic activity of the composites was evaluated in pure water and in a mixture of water and methanol under simulated sunlight and visible light illumination. Under simulated sunlight irradiation, the maximum hydrogen generation rate of 925 μmolh−1g−1 from a combination of water and methanol was attained, which is almost 7 times higher than hydrogen generation rate achieved with pure ZnO. The VL-ZnO/CNTs photocatalyst resulted in hydrogen production rate of 267 μmolh−1g−1 from the water-methanol medium when exposed to visible light. This rate was about 3.5 folds lower than that achieved under simulated sunlight illumination. This improvement in hydrogen production rate is attributed to large surface area, high photo-response, better separation/transportation of the charge carriers and synergistic impact of V, La and CNTs in the designed photocatalyst.

The photocatalytic performance of the semiconductor CdS can be improved with carbon materials capable of limiting photocorrosion and the fast recombination of photogenerated charges. For this purpose, carbon derived from biomass exhibit several advantages including low cost, high abundance, and renewability. Here, photocatalytic CdS nanorods modified with carbon derived from the leaves of Japanese raisin trees were synthesized via a single hydrothermal step. Composite CdS nanorods with 5% biomass-derived carbon photocatalyzed H2 evolution 1.8 times faster than unmodified CdS at a rate of 5.71 mmol g−1 h−1. The apparent quantum efficiency of 5%C/CdS nanorods was 14.96%. Furthermore, the addition of biomass-derived carbon to CdS nanorods augmented the stability of the semiconductor under visible light. The characterization of the composite PC indicated that a larger specific surface area, as well as upgraded charge separation caused by biomass-derived carbon, were involved in the acceleration of photocatalytic hydrogen production.

In the present work, the high-temperature and long-term hydrothermal stability of novel polyPOSS-imide membranes for high-temperature hydrogen separation is investigated. The polyPOSS-imide membranes are found to exhibit an appropriate stability up to 300 °C. Above this temperature the membrane selectivity rapidly decreases, which is seemingly related to changes in the molecular structure coupled to silanol condensation forming siloxane groups. Surprisingly, the exposure of the membrane to temperatures of up to 300 °C even increases the H2 permeance together with the selective feature of the polyPOSS-imide layer. Subsequently, the long-term hydrothermal stability of the polyPOSS-imide membranes was investigated over a period of close to 1000 h at 250 °C exposing the membrane to 10 mol% steam in the feed. An increase in H2/CH4 selectivity was observed upon water addition, and even though a minor drop was noticed over time during the hydrothermal operation, the selectivity exceeds the initial selectivity obtained in the dry feed atmosphere. After the removal of steam from the feed the performance returns to its original state prior to the exposure to any steam showing an appropriate steam stability of the polyPOSS-imide membranes. A conceptual process design and assessment was performed for application of these membranes involving a combination of carbon reuse and electrification of the steel making process with co-production of hydrogen. The results indicate a CO2 avoidance of 14%. The CO2 reduction achieved using renewable electricity in the proposed scheme is a factor 2.76 higher compared to a situation where the same renewable electricity would be fed in the electricity grid.

The detailed experimental studies of the autothermal and steam reforming of model mixtures simulating the composition of commercial diesel fuel were carried out over Rh/Ce0.75Zr0.25O2-δ-ƞ-Al2O3/FeCrAl wire mesh honeycomb catalytic modules. The components of the diesel surrogates were n-hexadecane, o-xylene, and naphthalene as model compounds of aliphatics, mono-aromatics and diaromatics, respectively. It was shown that low reaction rate of diaromatics steam reforming facilitated increasing concentration of C1–C5 hydrocarbon by-products (primarily ethylene) in the gas phase, as well as formation of polyaromatic compounds by concurrent condensation reaction. These undesirable processes were responsible for increasing catalyst coking. Monoaromatic constituents hadn't any significant effect on the progress of undesirable side-reactions during autothermal and steam reforming of diesel surrogates.

Over the last decade, as a consequence of the global decarbonization process, the interest towards green hydrogen production has drastically increased. In particular a substantial research effort has focused on the efficient and affordable production of carbon-free hydrogen production processes. In this context, the development of more efficient electrolyzers with low-cost electrode/electrocatalyst materials can play a key role. This work, investigates the fabrication of electrodes of nickel-zinc alloys with nanowires morphology cathode for alkaline electrolyzers. Electrodes are obtained by the simple method of template electrosynthesis that is also inexpensive and easily scalable. Through the analysis of the morphological and chemical composition of nanowires, it was found that the nanowires composition is dependent on the concentration of two metals in the deposition solution. Electrocatalytic tests were performed in 30% w/w potassium hydroxide aqueous solution at room temperature. In order to study the electrodes stability, mid-term galvanostatic test was also carried out. All electrochemical tests show that nanowires with about 44.4% of zinc have the best performances. Particularly, at −50 mAcm−2, these electrodes have an overpotential 50 mV lower than pure Ni nanowire. NiZn nanowires show also a good stability over time without noticeable signs of performance decay.

This study examines hydrogen-enriched kerosene combustion under distributed regime in a gas turbine combustion chamber. With hydrogen enrichment, it is aimed at increasing combustion performance of those fuels. However, in this circumstance, it is obvious to increase the flame temperature with taking place hydrogen enrichment. Thus colorless distributed combustion (CDC), which is one of the advanced combustion techniques, can be suggested to control flame temperature with slowing down the reaction rate, resulting in ultra-low NOX emissions and more uniform temperature distribution with a broadened flame. For this purpose, the hydrogen-enriched kerosene fuels were examined by modeling a CFD code using the eddy dissipation concept, the radiation model (P-1) and the turbulence model (standard k-epsilon). In this way, the thermal fields and the NOX distributions have been obtained. The results showed that hydrogen enrichment increased the flame temperatures from about 2490 K to 2605 K at air-combustion conditions until 30% H-2, resulting in the NOX levels predicted increased in the combustor. With reducing oxygen percentage the flame started to be the broadened one. The flame temperatures decreased, for instance, from about 2605 K to 2230 K at 15% O-2 for the 30% H-2 containing fuel. As a result of this, the NOX levels reduced from about 30 ppm to the values lower than 1 ppm in the combustor. It is concluded that increments in temperature and NOX levels with hydrogen can be suppressed with distributed regime, which enables that gas turbines can be operated at wider flammability limits with hydrogen enrichment.& nbsp;(c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

© 2021 Hydrogen Energy Publications LLCIn this study, hydrogen evolution electrodes are prepared by a 3D printing method using conductive PLA filament. To improve their conductivity and electrochemical performance, Nickel–Copper (NiCu) binary coating is deposited on 3D printed (3DP) electrodes in a solution bath with different volume ratios. Electrodes have been prepared as NixCux, NixCu2x, and NixCu3x according to Ni and Cu volume ratio (Ni–Cu; 10-10, 10–20, and 10–30 mL, respectively). Surface morphologies of the samples are measured using FE-SEM, EDX and XRD techniques. Electrochemical characterizations are investigated by LSV, CV and EIS. According to the results, the current density of NiCu coated 3DP electrodes is higher than the uncoated 3DP electrode. The results show that the resistance values of the electrodes are decreased from 0.262 kΩ to 0.187 kΩ in NixCu3x electrode.

Glycerol, as a main by-product of biodiesel synthesis, can be used in a large variety of applications including food, personal care, pharmaceutical and chemical industries However, due to the large production of biodiesel, the glycerol market was depressed. The conversion of glycerol into an energy carrier (syngas or hydrogen) could be a very interesting route to providing value as a renewable energy source. The reforming of glycerol leads to an almost complete conversion and very high carbon-to-gas efficiency with short residence time. In this work, the performances of packed bed reactor for hydrogen production from glycerol in supercritical conditions, by using a Ni-based catalyst supported on Al2O3 and SiO2, through CFD modelling in three-dimensions were studied. The parameters of kinetic model were determined by using an optimization method to fit the experimental data. The developed model was been validated based on experimental results published in literature for three different feed concentration of glycerol of 5, 10 and 20 wt% (R2 = 0.969). Varying the reaction temperature, between 500 and 800 °C, and residence time, between 1.5 and 10 s, the concentration of hydrogen increased with increasing the temperature and decreasing the residence time. At high temperature, the hydrogen can achieve a concentration of 65% and the present of methane is less than 5% and carbon monoxide maintain lower concentration. The simulation results show that high hydrogen yield can be obtained in short residence time with conversion of glycerol almost completed.

In this experimental study, the conversion of waste glycerol, derived from industrial biodiesel production process, to syngas in water vapor DC thermal arc plasma was carried out. Pure water vapor was used as a gasifying agent, a heat carrier and a plasma-forming gas. This enabled to avoid undesirable ballast products, such as nitrogen oxide, and obtain higher hydrogen and carbon monoxide concentration. It was found that a higher process efficiency (the concentration of H2 57.9 vol% and CO 21 vol%, the H2/CO ratio 2.76, the yield of H2 70 mol.% and CO 37 mol.%, the tar content 0.822 g/m3, the carbon conversion efficiency 68%, the energy conversion efficiency 39.5%) with a lower specific energy requirement (227.8 kJ/mol) was obtained at the highest H2O/C3H8O3 ratio of 1.9 (or water vapor flow rate of 14.76 kg/h, waste glycerol content of 7.88 kg/h, and the plasma torch power of 57 kW). This study is expected to provide an effective and advanced waste-to-energy solution.

This study reports the impacts of dual fuel mixtures on the theoretical performance characteristics of a spark ignition engine (SIE). The effects of addition of liquefied hydrogen, methane, butane, propane (additive fuels) into gasoline, iso-octane, benzene, toluene, hexane, ethanol and methanol fuels (primary fuels) on the variation of power, indicated mean effective pressure (IMEP), thermal efficiency, exergy efficiency, were examined by using a combustion model. The fuel additives were ranged from 10 to 50% by mass. The results exhibited that the ratios of hydrogen, methane, butane, propane noticeably affect the performance of the engine. The maximum increase ratio of power is 82.59% with 50% of toluene ratio and its maximum decrease ratio is 10.84% with 50% of methanol ratio in hydrogen mixtures. The maximum increase ratio of thermal efficiency and exergy efficiency are observed as 26.75% and 32.23% with the combustion of benzene-hydrogen mixtures. The maximum decrease ratio of thermal efficiency is 29.71% with the combustion of 50% of methanol ratio and it is 21.95% for the exergy efficieny with the combustion of 50% of ethanol ratio in hydrogen mixtures. The power, IMEP, thermal efficiency and exergy efficiency of primary fuels demonstrate different variation characteristics with respect to type and ratio of additive fuels.

MgH2-based nanocomposites were synthesized by high-energy reactive ball milling (RBM) of Mg powder with 0.5–5 mol% of various catalytic additives (nano-Ti, nano-TiO2, and Ti4Fe2Ox suboxide powders) in hydrogen. The additives were shown to facilitate hydrogenation of magnesium during RBM and substantially improve its hydrogen absorption-desorption kinetics. X-ray diffraction analysis showed the formation of nanocrystalline MgH2 and hydrogenation of nano-Ti and Ti4Fe2Ox. The possible reduction of TiO2 during RBM in hydrogen was not observed, which is in agreement with lower hydrogenation capacity of the corresponding composite, 5.7 wt% for Mg + 5 mol% nano-TiO2 compared to 6.5 wt% for Mg + 5 mol% nano-Ti. Hydrogen desorption from the as-prepared composites was studied by Thermal Desorption Spectroscopy (TDS) in vacuum. A significant lowering of the hydrogen desorption temperature of MgH2 by 30–90 °C in the presence of the additives is associated with lowering activation energy from 146 kJ/mol for nanosized MgH2 down to 74 and 67 kJ/mol for MgH2 modified with nano-TiO2 and Ti4Fe2O0.3 additives, respectively. After hydrogen desorption at 300–350 °C, these materials are able to absorb hydrogen even at room temperature. It is shown that nano-structuring and addition of Ti-based catalysts do not decrease thermodynamic stability of MgH2. The thermodynamic parameters, obtained from hydrogen desorption isotherms for the Mg–Ti4Fe2O0.3 nanocomposite, ΔHdes = 76 kJ/mol H2 and ΔSdes = 138 J/K·mol H2, correspond to the reported literature values for pure polycrystalline MgH2. Hydrogen absorption-desorption characteristics of the composites with nano-Ti remain stable during at least 25 cycles, while a gradual decay of the reversible hydrogen capacity occurred in the case of TiO2 and Ti4Fe2Ox additives. Cycling stability of Mg/Ti4Fe2Ox was substantially improved by introduction of 3 wt% graphite into the composite.

In recent years, Co, N co-doped carbon (Co–N–C) materials as oxygen reduction reaction (ORR) catalysts have attracted great attention because of their good ORR stability as well as decent activity. Co-doped zeolitic imidazolate framework-8 (Co@ZIF-8) as the precursor for synthesizing Co–N–C has attracted great interest recently. Co@ZIF-8 synthesis method may affect the properties of the as-synthesized Co@ZIF-8 precursors, which will surely affect the properties and ORR performance of Co@ZIF-8-derived Co–N–C catalysts. Herein, three methods, viz. room-temperature stirring method, reflux method, and hydrothermal method, were used to synthesize Co@ZIF-8 precursors. Physical characterization shows that the synthesis method has a great influence on the textural properties, composition, and graphitization degree of the as-synthesized Co–N–C catalysts. Electrochemical characterization shows that Co–N–C-R synthesized with reflux method exhibits an onset potential (Eonset) of 0.905 V, a half-wave potential (E1/2) of 0.792 V and a limiting current density (JL) of 5.85 mA cm−2 in acidic media, which are higher than those of Co–N–C–S (Eonset = 0.870 V, E1/2 = 0.770 V, JL = 4.71 mA cm−2) and Co–N–C–H (Eonset = 0.892 V, E1/2 = 0.785 V, JL = 4.68 mA cm−2) synthesized with room-temperature stirring method and hydrothermal method, respectively. The better ORR activity observed on Co–N–C-R can be attributed to its larger graphitization degree and larger mesopore volume. Catalytic stability test shows that Co–N–C-R has negligible activity loss after 5000 potential cycles. This work demonstrates that reflux method is a more suitable method for synthesizing Co–N–C catalysts for ORR.

Water electrolysis is a promising approach for the sustainable production of hydrogen, however, the unfavorable thermodynamics and sluggish kinetics of oxygen evolution reaction (OER) are associated with high anodic potentials. To lower the required potentials, an effective strategy is proposed to substitute OER with partial oxidation of degradation products of carbohydrate origin from the waste stream of a chemical pulping industry. In this work, two different catalytic materials – PdNi and NiO are investigated comparatively to understand their catalytic performance for the oxidation of carbohydrate alkaline degradation products (CHADs). PdNi can catalyze CHADs with low potential requirements (−0.11 V vs. Hg/HgO at 150 mA cm−2) but is limited to current densities

Active aluminum composites are considered to be ideal materials that can be applied to mobile hydrogen sources in light of their high hydrogen generation efficiency, simple preparation, rapidly reaction rate, and non-pollution reaction products. Whereas, the dense alumina shell on the surface of the aluminum powder greatly limits the reaction between aluminum and water. This article reviews the common preparation methods, additives, reaction mechanism, aging and preservation methods of activated aluminum composites, and the latest progress in the application of active aluminum composites are also summarized. In addition, some recommendations are also given for future research work on active aluminum composites.