Exploring highly efficient and inexpensive hydrogen evolution reaction (HER) electrocatalysts for various electrochemical energy conversion technologies is actively encouraged. Herein, a 3D ...urchin‐like Mo‐W18O49 nanostructure as an efficient HER catalyst is reported for the first time. The obtained Mo‐W18O49 catalyst exhibits excellent electrocatalytic activity toward HER with small onset potential and Tafel slope. The prepared Mo‐W18O49 electrode shows excellent durability after a long period. Density functional theory calculations reveal that the remarkably enhanced performance of Mo‐W18O49 can be due to the ability of Mo dopant to increase the number of active sites, leading to optimal hydrogen adsorption on the active sites because of the electronic and geometric modulation. In addition, the urchin‐like 3D morphology with a high surface area and abundant 1D nanowires promotes electron transfer, thereby ensuring fast interfacial charge transfer to improve electrocatalytic reactions. All these experimental and theoretical results clearly reveal that Mo‐W18O49 intrinsically improves HER activity and thus has potential applications in water splitting.
The 3D urchin‐like Mo‐W18O49 catalyst exhibits excellent electrocatalytic activity toward HER with small onset potential and Tafel slope, as well as excellent durability. The remarkably enhanced performance of Mo‐W18O49 can be ascribed to the synergistic effect of an increased amount of active sites and of activity improvment by Mo dopant, furthermore abundant agminated 1D nanowires also provide a high surface area.
Fe/N/C is a promising non‐Pt electrocatalyst for the oxygen reduction reaction (ORR), but its catalytic activity is considerably inferior to that of Pt in acidic medium, the environment of polymer ...electrolyte membrane fuel cells (PEMFCs). An improved Fe/N/C catalyst (denoted as Fe/N/C‐SCN) derived from Fe(SCN)3, poly‐m‐phenylenediamine, and carbon black is presented. The advantage of using Fe(SCN)3 as iron source is that the obtained catalyst has a high level of S doping and high surface area, and thus exhibits excellent ORR activity (23 A g−1 at 0.80 V) in 0.1 M H2SO4 solution. When the Fe/N/C‐SCN was applied in a PEMFC as cathode catalyst, the maximal power density could exceed 1 W cm−2.
A non‐precious Fe/N/C electrocatalyst was prepared through pyrolysis of Fe(SCN)3, poly‐m‐phenylenediamine, and carbon black. The obtained Fe/N/C catalyst has high level of S doping and high surface area, and thus exhibits excellent catalytic activity for the oxygen reduction reaction in acidic solution. A polymer electrolyte membrane fuel cell using this catalyst as the cathode can yield a maximal power density as high as 1.03 W cm−2.
Salt lake brine is an abundant lithium resource and has great developing value and potentiality. But the Mg/Li ratio of some salt lakes in China and Dead Sea in Jordan is extremely high. In this ...study, electrodialysis (ED) with monovalent selective ion-exchange membranes was used to investigate the separation performance of Li+/Mg2+ from synthetic multinary mixture. The effects of operating conditions on the lithium recovery, permselectivity, and Mg/Li ratio of the product were evaluated. The results indicate that ED with monovalent selective ion-exchange membranes has a significant separation effect on Li+/Mg2+. When the optimized parameters were used in ED, the Mg/Li mass ratio of the product stream was reduced to 8.0 (18.8 times compared to a feed Mg/Li ratio of 150), and simultaneously, the Li+ recovery reached to 95.3%. Compared to nanofiltration, ED exhibited superiority both technically and economically for the fractionation of Li+/Mg2+. It was also verified that the presence of co-existing cations would not be detrimental to the feasibility of lithium extraction using ED. Meanwhile, the separation mechanism of ED process was discussed qualitatively.
•Electrodialysis (ED) was used to treat a saline water with a high Mg/Li ratio.•The main objective of this study was to significantly reduce the Mg/Li ratio.•The Mg/Li ratio can be decreased as high as 21.8 times via ED, and the Li+ recovery can reach over 90%.•ED was proven to be technically and economically feasible to separate lithium from salt lake brine with high Mg/Li ratio.•The selective separation mechanism of ED was qualitatively discussed.
•Three kinds of foaming agents are used to prepare foamed concrete.•The stability and strength of the foam produced by foaming agents were tested.•The performance of foamed concrete were ...characterized.•A close correlation was found between foaming agent and performance of specimens.
Aiming to explore the effects of the foaming agent type on the properties of foamed concrete, synthetic surfactants (SS), plant surfactants (PS) and animal glue/blood based surfactants (AS) were used to produce foamed concrete with a density of 600 kg/m3. At this density, the structure and properties of foamed concrete were greatly influenced by the foaming agent type. The FTIR results show that the functional groups of SS, PS and AS are similar. However, the stability and strength of the foam made by SS are much higher than that of AS and PS, which may be due to the higher density and viscosity of SS foam. The experimental results exhibited that the compressive strength of foamed concrete with SS is 11% and 43% higher than that of foamed concrete with AS and PS, respectively. The drying shrinkage of foamed concrete with SS is 13% and 21% lower than that of foamed concrete with AS and PS, respectively. The pore structure of foamed concrete was tested with X-CT and Hardened Concrete Bubble Analyzer. Foamed concrete with SS showed narrower pore size distributions and fewer connected pores compared with the other two, which accounted for the high compressive strength, low drying shrinkage and strong frost resistance of foamed concrete with SS.
Visible light along with 5 mol % of rose bengal catalyzes the direct S–P(O) coupling between thiols and P(O)H compounds in the presence of air as the green oxidant. The protocol is operationally ...simple and amenable to gram-scale synthesis. A variety of S–P(O) coupling products can be readily prepared in moderate to excellent yields. The reaction features good functional-group tolerance, operational simplicity, and excellent practicality.
Inorganic binder-based stabilization/solidification (S/S) of Pb-contaminated soil is a commonly used remediation approach. This paper investigates the influences of soluble Pb species on the ...hydration process of two types of inorganic binders: ordinary Portland cement (OPC) and magnesium potassium phosphate cement (MKPC). The environmental leachability, compressive strength, and setting time of the cement products are assessed as the primary performance indicators. The mechanisms of Pb involved in the hydration process are analyzed through X-ray diffraction (XRD), hydration heat evolution, and thermogravimetric analyses. Results show that the presence of Pb imposes adverse impact on the compressive strength (decreased by 30.4%) and the final setting time (prolonged by 334.7%) of OPC, but it exerts much less influence on those of MKPC. The reduced strength and delayed setting are attributed to the retarded hydration reaction rate of OPC during the induction period. These results suggest that the OPC-based S/S of soluble Pb mainly depends on physical encapsulation by calcium-silicate-hydrate (CSH) gels. In contrast, in case of MKPC-based S/S process, chemical stabilization with residual phosphate (pyromorphite and lead phosphate precipitation) and physical fixation of cementitious struvite-K are the major mechanisms. Therefore, MKPC is a more efficient and chemically stable inorganic binder for the Pb S/S process.
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•Pb mainly delays the induction period during OPC hydration.•Pb incorporation reduces strength of OPC-based S/S cubes by 30.4%.•MKPC is a more efficient inorganic binder for Pb S/S with low leachability.•MKPC-based S/S depends on phosphate precipitation and struvite-K encapsulation.
Electrocatalytic Ammonia Synthesis Process on the Mo2TiC2 MXene.
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•Nineteen different possible pathways (five association pathway and fourteen dissociation pathway) analyzed by DFT ...calculation and Gibbs free energy calculation.•Valid N2-philicity, N≡N triple bond of the N2 molecule (the optimal distance) is sufficiently activated, from 1.11 Å to 1.268Å•Mo2TiC2 MXene can reduce the overpotential by changing the reaction pathway.•Mo2TiC2 as an ordered, double transition metals carbides is an eligible electrocatalyst for the NRR
Electrocatalytic ammonia synthesis provides an energy-efficient alternative to the Haber−Bosch process. The aim is to find promising electrocatalysts which are able to change the reaction pathway and reduce the overpotential. Here, based on density functional theory, a comprehensive mechanism study of the N2 activation and NH3 synthesis on the Mo2TiC2 MXenes is presented. For catalytic reaction mechanism, nineteen different possible pathways are screened for the lowest overpotential, where the corresponding potential-determining step are compared by Gibbs free energy calculation. The result reveals Mo2TiC2 MXenes exhibit both valid N2-philicity and high catalytic activity for electrocatalytic ammonia synthesis through a dissociation mechanism with a low overpotential of 0.26 V. Further, the competing reaction of H2 evolution is simultaneously suppressed which shows a relatively high potentials of 0.74 V. This study shows a brand new material for catalyzing NH3 synthesis under ambient conditions and provides the theory background to reduce the overpotential by changing the reaction pathway.
A unique ethanol‐precursor‐based LPCVD route is developed for the fast (4 min, improved 20 times) and scalable (25 inch, improved six times) growth of high‐quality graphene glass. The obtained ...graphene glass presents high uniformity across large areas and is demonstrated to be an excellent material for constructing switchable windows and biosensor devices, owing to its excellent transparency and conductivity.
Abstract Lysosomes have recently been regarded as the attractive pharmacological targets for selectively killing of cancer cells via lysosomal cell death (LCD) pathway that is closely associated with ...reactive oxygen species (ROS). However, the details on the ROS-induced LCD of cancer cells are still poorly understood, partially due to the absence of a lysosome-targetable, robust, and biocompatible imaging tool for ROS. In this work, we brought forward a Si-rhodamine-based fluorescent probe, named PSiR , which could selectively and sensitively image the pathologically more relavent highly reactive oxygen species (hROS: HClO, HO , and ONOO− ) in lysosomes of cancer cells. Compared with many of the existing hROS fluorescent probes, its superiorities are mainly embodied in the high stability against autoxidation and photoxidation, near-infrared exitation and emission, fast fluorescence off−on response, and specific lysosomal localization. Its practicality has been demonstrated by the real-time imaging of hROS generation in lysosomes of human non-small-cell lung cancer cells stimulated by anticancer drug β-lapachone. Moreover, the probe was sensitive enough for basal hROS in cancer cells, allowing its further imaging applications to discriminate not only cancer cells from normal cells, but also tumors from healthy tissues. Overall, our results strongly indicated that PSiR is a very promising imaging tool for the studies of ROS-related LCD of cancer cells, screening of new anticancer drugs, and early diagnosis of cancers.
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