Latest ArticlesHighly active and durable oxygen reduction reaction (ORR) catalysts with sufficient activity and stability of Pt are beneficial for the commercialization of proton exchange membrane fuel cells. Here we report an effective approach to prepare a composite catalyst comprising of ordered L12-Pt3Fe intermetallic nanoparticles interact with single atom Fe-Nx-Cy active sites. The addition of Fe and the confinement effect of hierarchical porous structure limit the growth of intermetallic particle size (around 2.5 nm). The ligand effect of the electron transfer from Fe to Pt and the synergistic interaction between L12-Pt3Fe and Fe-Nx-Cy work together to reduce oxygen intermediates adsorption and improve kinetics process. Experimentally, the L12-Pt3Fe/CFe-N-C catalyst shows high mass activity and specific activity at 1.010 A/mgPt and 1.166 mA/cm2, respectively, which are 5.8 and 5.1 times higher than those of commercial Pt/C (0.174 A/mgPt and 0.230 mA/cm2). Thanks to the more stable L12 structure, L12-Pt3Fe/CFe-N-C exhibits better durability (14 mV E1/2 loss of L12-Pt3Fe/CFe-N-C and 33 mV E1/2 loss of commercial Pt/C) after 30,000 cycles accelerated stress tests. The strategy to design and prepare small particle Pt-based intermetallic alloys coordinated with M-N-C active sites provides a new direction to obtain low-cost and easily prepared effective ORR catalysts.
Considering the earth powered by intermittent renewable energy in the coming future, solid oxide electrolysis cell (SOEC) will play an indispensable role in efficient energy conversion and storage on demand. The thermolytic and kinetic merits grant SOEC a bright potential to be directly integrated with electrical grid and downstream chemical synthesis process. Meanwhile, the scientific community are still endeavoring to pursue the SOEC assembled with better materials and operated at a more energy-efficient way. In this review article, at cell level, we focus on the recent development of electrolyte, cathode, anode and buffer layer materials for both steam and CO2 electrolysis. On the other hand, we also discuss the next generation SOEC operated with the assistant of other fuels to further reduce the energy consumption and enhance the productivity of the electrolyzer. And stack level, the sealant, interconnect and stack operation strategies are collectively covered. Finally, the challenges and future research direction in SOECs are included.
Selenium (Se) is an essential mineral element for human and other animals, and has been proved to improve plant growth and development and tolerance to different abiotic stresses. Selenium biofortification is considered to be a key strategy to increase the selenium content of edible parts of crops, which is helpful for improving human health. In this work, foliar fertilization with different concentrations and selenium forms was carried out on two wheat varieties at the flowering stage to compare the selenium enrichment effect of Na2SeO3, methylselenized selenocysteine (MSC), methylselenized glucose (MSG) and methylselenized lactide (MSL) in wheat grains. Surprisingly, MSG was found to be the preferable fertilizer. After the application of MSG, the highest selenium content in wheat gains reached 6 mg/kg in this experiment, and the average selenium content was 2–4 times versus that of Na2SeO3 application. Since MSG has high utilization rate and is easily available at relatively low cost, it can be employed as a potential selenium source for selenium biofortification to enhance the added value of agricultural industry.
An unprecedent [4 + 3] cycloaddition of furoketenimines with furocarbenoids has been disclosed for the divergent and efficient synthesis of cycloheptafuran and cycloheptapyrrole scaffolds. Zinc chloride acted as promoters for both the formation of these two transient intermediates from isocyanides and ene-yne-ketones, and the subsequent construction of seven-membered ring. Three rings and five bonds were constructed successively in this three-component one-pot domino reaction.
Two-dimensional (2D) layered materials with layer-number dependent properties are promising candidates for next-generation noble-metal-free electrocatalytic reaction. However, the main group metal chalcogenides (MMCs) used for this purpose are rarely explored. Herein, we report the controlled growth of indium selenide (InSe) with a novel morphology (semispherical array) on a silicon substrate and its application in hydrogen evolution reaction (HER). The formation of the spherical InSe is explained with a vapor-liquid-solid growth mechanism, in which the distribution and size of the spheres could be facilely tuned by the reaction parameters. The InSe semispherical array was demonstrated as more efficient catalyst for HER than the flake-like 2D InSe counterparts, originating from the fully exposed InSe spherical surface with abundant adsorbing sites and the high crystalline quality for electron transport. This work provides a controlled synthesis way of the layered InSe with a distinct spherical morphology used for the electrocatalysis applications and could be extended to other main group metal chalcogenides.
Obesity, characterized by the dysregulation of energy balance in adipose tissue and other metabolic organs, is frequently accompanied by chronic low-grade inflammation. As long-acting insulin sensitizers, the organically-derivatized polyoxovanadates (POVs), can extend the dosing interval of antidiabetic drugs from hourly to almost daily. In this work, the protective activity of POVs is investigated by an eight-week in vivo experiment, in which a small amount of POVs was administrated orally to a mouse model of diet-induced obesity every day. The present study shows that administration of POVs significantly decreases the body weight of mice, reduces adipose tissue accumulation, and simultaneously reduces adipose tissue inflammation. In addition, the anti-obesogenic population of iNKT cells is protected potentially by POVs, which subsequently alleviates visceral adipose tissue inflammation in high-fat-diet (HFD)-fed mice against diet-induced obesity. By contrast, the change in body weight after POV treatment is the result of a substantial reduction in fat mass, with no obvious effects on lean body mass. These findings demonstrate that supplementary of POVs would be an effective way to combat obesity and metabolic disorders while lowering metabolic inflammation.
The growth of dendrites in the lithium (Li) metal anode hinders the commercialization of lithium metal batteries (LMBs). Electrolyte additives have proved to be an effective way to solve the problem of dendrites and improve the coulombic efficiency. Herein, we propose a strategy of using l-tyrosine (l-Tyr) as an additive to protect the lithium metal anode in situ, where l-Tyr can be electropolymerized in situ to form an ordered array of nanosheets on the surface of the lithium metal anode to uniformly deposit lithium ions. At the same time, the addition of l-Tyr changed the structure of the solvent in the electrolyte, because the carboxyl group on l-Tyr make DME form hydrogen bonds easily. Besides, the reduction of free DME makes more TFSI− involved in the formation of the SEI film on the electrode surface, which increases the proportion of LiF in the SEI film. With 2 wt% l-Tyr, Li||Li symmetric cells superior cycle stability in ether electrolytes, Li|Cu cells y improved stability up to 200 cycles with an average CE of 93.1% in ether electrolytes and Li||Li4Ti5O12 (LTO) demonstrated an excellent cycling capabilitie with 119 mAh/g capacity retention by the 5000th cycle.
Carbon dioxide (CO2) is an attractive C1 building block in chemical synthesis due to its abundance, availability and sustainability. However, the low reactivity and high stability generally limits its transformations under mild conditions to value added chemicals. Recent advances in flow chemistry provide effective means for the chemical transformation of CO2, and many new methods and techniques that fully utilized the advantages of continuous flow platforms for the chemical fixation of CO2 have been realized. In view of the rapid development and the urgent need for continuous transformation of CO2, herein we wish to present an update of the recent advances in this research area.
Metal-free carbon catalysts with excellent conduction performance have drawn much research attention in reduction reactions. Herein, a N, B co-doped carbon catalyst with high pyrrolic N proportion (35.75%) and excellent surface area (1409 m2/g) was successfully prepared via carbonizing covalent organic framework materials (COFs) containing N and B atoms assisted by ZnCl2 molten salt. The presence of ZnCl2 maintains the micropore structure of COFs to provide high specific surface areas and abundant lattice defects for carbon materials. In addition, electron-withdrawing B heteroatom further facilitates the formation of pyrrolic N at defect sites by modifying the electronic structure of carbon network. The tuning of surface areas and active N species in carbon catalysts successfully improve the selective hydrogenation of nitrobenzene to aniline. The optimized carbon material exhibits excellent nitrobenzene conversion (99.9%) and aniline selectivity (> 99%) within 15 min, as well as excellent substrate suitability. This work provides a certain guiding for the design and application of metal-free catalysis.
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