The technical possibility and possible issues of an intermediate–temperature–operated polymer electrolyte fuel cell (@120 °C) is investigated with an eye toward the launching of new fuel cell ...heavy–duty vehicles on the world market. Commercial perfluorosulfonic acid membrane and a commercial Pt catalyst supported on carbon are selected to clarify the possible issues in the fuel cells. The cell resistivity at high humidity is less than 0.1 Ω cm
–2
. The mass activity (@ 0.85 V, Pt loading amount: 0.33 mg
Pt
cm
−2
) approaches 850 A g
Pt
–1
. The high gas crossover rate through the membrane leads to decreased open circuit voltage, which necessitates the use of higher Pt loadings (>0.30 mg
Pt
cm
–2
) at the cathode to mitigate the effect of the mixed potential. Pt degradation during 120 °C operation at low humidity is found to be much lower than that during 80 °C operation at high humidity based on the results of load–cycle durability testing.
In this work, pyroelectric materials can spontaneously polarize and generate an internal electric field when heated, and the photocatalyst will have band bending under the action of the internal ...electric field, which promotes the separation of photogenerated carriers. When HCN@PVTC@CdS is used as a photocathode pole, due to the presence of internal electric field generated by pyroelectric effect, the photocatalyst attached to the pyroelectric material will be affected, and its energy band will bend, which is conducive to the separation of photogenerated charge carriers, accelerating the reaction kinetics of the battery.
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Zinc–air battery as one of the new generations of battery system, its theoretical specific energy is as high as 1086 Wh kg−1, specific capacity up to 820 mAh/g, and zinc has the advantages of environmental friendliness, resource abundance, low cost and good safety, so it has attracted much attention. However, due to its slow reaction kinetic process, zinc–air battery will produce a large charging overpotential usually up to 2 V, it is far beyond the theoretical voltage of 1.65 V, so reducing the overpotential of zinc–air batteries is extremely necessary, and the most common way to solve this problem is to use excellent catalyst cathode to improve the oxygen reduction and oxygen evolution kinetics of zinc–air batteries. So we developed a new photothermal assisted zinc–air battery system with Hollow carbon nanosphere@poly (vinylidene fluoride-trifluoroethylene-chlorofluoroethylene)@CdS(HCN@PVTC@CdS) photocathode, the pyroelectric and photocatalysis effect can effectively promote the reaction kinetics and reduce the reaction overpotential. With the pyroelectric and photocatalysis synergistic effect, the zinc–air has displayed a high discharge potential of 1.33 V and a low charging potential of 1.5 V with good cycle stability. This multi-assist technology with built-in electric and light fields paves the way for the development of high-performance zinc–air batteries and other energy storage systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Natural and earth abundant pyrite was evaluated for Oxygen evolution reaction(OER) during water electrolysis•The natural catalyst demonstrated least overpotential of 205 mV for OER at 10mA/cm2 in ...alkaline media.•The OER activity of pyrite sample is much superior than precious benchmark catalyst, IrO2.•The catalyst is stable and is expected to replace costlier IrO2 for sustainable development.
The fabrication of an economical, earth-abundant, environment-friendly, and highly efficient electrocatalyst for anodic oxygen evolution reaction (OER) in the electrolysis of water is essential for sustainable energy conversion and storage technology. Among the various transition metal-based electrocatalysts, iron-based electrocatalysts are well-known for their catalytic behavior due to their effective redox activity, abundance, and low toxicity. Pyrites are the most prevalent Fe-containing minerals in the earth's crust, but their use as an electrocatalyst for oxygen evolution reaction (OER) has received little attention though their synthetic counterparts have shown better activity. Herein, the naturally occurring pyrite (FeS2) on Ni foam is evaluated as a dynamic electrocatalyst towards OER in alkaline media. Various spectro-analytical techniques have been used to confirm the chemical and physical characteristics of earth abundant pyrite. The pyrite-coated nickel foam exhibited an extraordinarily superior catalytic activity for OER with overpotential of 203 and 315 mV at current densities of 10 mA∙cm−2 and 50 mA∙cm−2, respectively in 1.0 M potassium hydroxide (KOH) electrolyte at a scan rate of 5 mV∙s−1. Meanwhile, the benchmark precious iridium oxide (IrO2) on nickel foam demonstrated an overpotential of 322 and 430 mV for OER at 10 and 50 mA∙cm−2, respectively. It's important to note that the catalyst used is a natural pyrite with some additional constituents in small quantities. Therefore, the analysis revealed the presence of carbon (C), silicon (Si) and oxygen (O) in addition to FeS2. This composition, along with the synergistic behavior of nickel ions from the nickel foam, likely contributes to the enhancement in catalytic activity observed. The pyrite on carbon substrate, did not exhibit the same impressive OER activity as like on Ni foam, emphasizing the significance of the substrate-dependent performance. Nevertheless, on the nickel foam, natural pyrite displayed the lowest overpotential, Tafel slope, and better stability for OER. Hence, on Ni foam substrate, earth-abundant, low-cost, stable, and efficient pyrite-based catalyst augmented by synergistic interactions with nickel ions, may hold great promise for advancing the field of water electrolysis and facilitating cleaner energy production and conversion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•Electro-oxidation was first used to extract bromine from (concentrated) seawater.•High concentration of chloride did not hinder but promoted bromide oxidation.•Hardness ions in ...concentrated seawater had little influence on bromide oxidation.•Selective electro-oxidation of bromide showed low energy consumption.
Comprehensive utilization of concentrated seawater is a significant means to promote the development of the desalination industry, and then effectively relieve the freshwater crisis in coastal areas. Bromine exists in (concentrated) seawater as the main element, and is an important basic chemical. Its extraction becomes an important aspect of comprehensive utilization of concentrated seawater. Selective oxidation of bromide using a three-electrode system and an electrolyzer, was applied to extract bromine from concentrated seawater. It was feasibility for selective oxidation of bromide at the anode potential between 1.0 V and 1.5 V (with respect to the standard hydrogen electrode, SHE). Within this potential range, the formation of bromine was favored over that of chlorine and oxygen with the graphite rod electrode used in this study. Chloride was difficult to be oxidized at the selected anode potential (1.350 V vs. SHE) even though its concentration was very high. Both chloride and sulfate as coexisting ions showed a promoting effect on the electro-oxidation of bromide due to their contribution to the total conductivity of the solution. However, hardness ions such as calcium ion and magnesium ion had little effect on selective oxidation of bromide. Taking yield of bromine, current efficiency and energy consumption into overall consideration, operation time from 4 h to 10 h might be optimal in the process of treating concentrated seawater.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The electrochemical reduction of N2 is an important industrial process, which offers an alternative route to the Haber-Bosch procedure for NH3 production. Here, by the method of first-principles ...calculations, we introduce Ni4 supported defective graphene (Ni4-Gr) as an efficient substrate to convert N2 into NH3. The enzymatic, alternating and distal mechanisms are investigated for N2 reduction to explore catalytic activity of Ni4-Gr surface. By analyzing the free energy diagrams, it is obtained that Ni4-Gr exhibits high catalytic performance for N2 reduction via the enzymatic pathway with an overpotential value of 0.50 V at normal temperature.
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•Ni4 cluster can be stably deposited on monovacancy defective graphene.•N2 molecule is largely activated on Ni4-Gr.•The activated N2 is converted to NH3 via enzymatic mechanism.•The enzymatic mechanism proceeds with an overpotential value of 0.50 V.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Nanostructured NiMoO4 synthesized using a facile and simple hydr4othermal method for OER applications.•The BET surface areas of the NiMoO4-6 h, NiMoO4-12 h, and NiMoO4-24 h were ...found to be 53.75, 60.06, 46.53 m2/g, respectively.•The NiMoO4 exhibited excellent overpotential of 315, 290, and 320 mV for NiMoO4-6 h, NiMoO4-12 h, and NiMoO4-24 h, respectively at 10 mA cm−2.•Furthermore, the NiMoO4-12 h showed a very good stability and only 1.28 % deduction was observed after 200 h at a constant current density of 10 mA cm−2.
Bifunctional electrocatalysts derived from earth-abundant transition metals are a promising substitute for noble metals in general water electrolysis, but their low activity and short durability limit their application. Herein, a nickel molybdate nanoparticles decorated on nickel foam (NiMoO4/NF NPs) electrode was fabricated by a facile hydrothermal method at three different time intervals (6, 12, and 24 h) and verified for the oxygen evolution reaction (OER). The constructed electrodes exhibited high OER activity in 1.0 M KOH with overpotentials of 315 mV, 290 mV and 320 mV for NiMoO4-6 h, NiMoO4-12 h, and NiMoO4-24 h, respectively. In addition, the NiMoO4-12 h electrodes displayed remarkable durability with a negligible reduction of 1.28 % at a current density of 10 mA cm−2 for 200 h. This research work delivers a new pathway to improve the electrocatalytic behaviour of the catalysts by synergistically moderating the inherent electrical conductivity, efficient surface moieties, and surface reaction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We study the relationship between Li2O2 morphology and the electrochemical performance of the Li–O2 battery using a combination of experiment and theory. Experimental Li–O2 battery discharge curves ...are accurately captured by a theoretical model in which electrode performance is limited by the nucleation and growth of discrete Li2O2 nanostructures in the cathode. We further show that the characteristic sharp voltage drop widely reported at the end of discharge results from the decrease in electrochemical surface area as Li2O2 covers the cathode surface. Preventing surface nucleation is highlighted as a core strategy for increasing Li–O2 battery capacity.
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IJS, KILJ, NUK, PNG, UL, UM
Novel cathodes based on Sb‐doped tin oxide (STO)‐supported Ru particles enable Li–O2 batteries to be operated below 4.0 V, which is of crucial importance for the realization of rechargeable Li–O2 ...batteries, and to deliver a high specific capacity of 750 mA h g−1 even after 50 discharge–charge cycles at 0.1 mA cm−2.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
