Atomically precise Pd6(SC12H26)12 nanoclusters were synthesized and investigated as electrocatalysts for the hydrogen and oxygen evolution reactions. The present study shows the high catalytic ...performances of the Pd6 clusters, the key role of the outer-shell electronic state of the metal core in mediating the catalytic properties and the double-edged function of the protecting ligand in the catalytic reactions.
In this study, two-dimensional (2D) and three-dimensional (3D) freestanding reduced graphene oxide-supported Cu2O composites (Cu2O-rGO) were synthesized via simple and cost-efficient hydrothermal and ...filtration strategies. The structural characterizations clearly showed that highly porous 3D graphene aerogel-supported Cu2O microcrystals (3D Cu2O-GA) have been successfully synthesized, and the Cu2O microcrystals are uniformly assembled in the 3D GA. Meanwhile, paper-like 2D reduced graphene oxide-supported Cu2O nanocrystals (2D Cu2O-rGO-P) have also been prepared by a filtration process. It was found that the products prepared from different precursors and methods exhibited different sensing performances for H2O2 detection. The electrochemical measurements demonstrated that the 3D Cu2O-GA has high electrocatalytic activity for the H2O2 reduction and excellent sensing performance for the electrochemical detection of H2O2 with a detection limit of 0.37 μM and a linear detection range from 1.0 μM to 1.47 mM. Meanwhile, the 2D Cu2O-rGO-P structure also showed good electrochemical sensing performance toward H2O2 detection with a much wider linear response over the concentration range from 5.0 μM to 10.56 mM. Compared to the previously reported sensing materials, the as-obtained 2D and 3D Cu2O-rGO materials exhibited higher electrochemical sensing properties toward the detection of H2O2 with high sensitivity and selectivity. The 2D and 3D Cu2O-rGO composites also exhibited high sensing performance for the real-time detection of H2O2 in human serum. The present study indicates that 2D and 3D graphene-Cu2O composites have promising applications in the fabrication of nonenzymatic electrochemical sensing devices.
We show that a model featuring an average commodity factor, a carry factor, and a momentum factor is capable of describing the cross-sectional variation of commodity returns. More parsimonious one- ...and two-factor models that feature only the average and/or carry factors are rejected. To provide an economic interpretation, we show that innovations in global equity volatility can price portfolios formed on carry, while innovations in a commodity-based measure of speculative activity can price portfolios formed on momentum. Finally, we characterize the relation between the factors and the investment opportunity set.
Data and the Internet appendix are available at
https://doi.org/10.1287/mnsc.2017.2840
This paper was accepted by Neng Wang, finance.
To obtain stable and ultrafine Pt nanoclusters, a trigonal prismatic coordination cage with the sulfur atoms on the edges was solvothermally synthesized to confine them. In the structure of ...{Ni24(TC4A-SO2)6(TDC)12 (H2O)6} (H4TC4A-SO2 = p-tert-butylsulfonylcalix4arene; H2TDC = 2,5-thiophenedicarboxylic acid), three Ni4-(TC4A-SO2) SBUs are bridged by three TDC ligands into a triangle and two such triangles are pillared by three pairs of TDC ligands to form a trigonal prism. The cage cavity has 12 sulfur atoms on the surface. Because of the porous structure and strong covalent interaction between metal and sulfur, ultrafine Pt nanoclusters composed of less than ∼18 Pt atoms can be facilely confined in the present trigonal prismatic cage (Pt@CIAC-121). The as-synthesized Pt NCs exhibit higher electrocatalytic activity than commercial Pt/C toward hydrogen evolution reaction.
The electrochemical production of H2O2 from O2 catalyzed by Au25(SC12H25)18 was studied as a function of the charge state (-1, 0 and +1). Maximum H2O2 production (∼90%) was obtained from the ...negatively charged clusters (Au25(-)) due to the efficient electron transfer from the anionic Au25(-) cluster into the LUMO (π*) of O2.
A series of nonbridged axially chiral binaphthyl derivatives were synthesized and used as chiral dopants for chiral nematic liquid crystals (N*-LCs). It was found that binaphthyl derivatives ...substituted at 3,3′ positions or 2,2′ positions of binaphthyl rings could induce N*-LCs to show opposite circularly polarized luminescence (CPL) signals, despite having the same configuration. Additionally, a CPL switch could be constructed in these N*-LCs regulated by the applied electric field.
Chiral liquid crystals (N*-LCs) induced by binaphthyl derivatives which have the same (
R
)-configuration exhibited opposite circularly polarized luminescence.
Online Innovation Community (OIC) serves as a virtual space for users to exchange products and services, and share knowledge and information. Previous studies have indicated that community climate is ...an important factor affecting users' value co-creation behavior, however, the influencing process has not been clearly revealed from the perspective of motivation. In this study, we explored the relationship between online innovation community climate (supportive climate and controlling climate), user motivation and value co-creation behavior (user's participation behavior and user's citizenship behavior) based on the SOR model. The study sample included 29,835 pieces of information from 3,315 users in 14 product sections of the OnePlus Community which were analyzed with Mplus8.1. The findings revealed that: (1) The supportive climate had a positive impact on user's citizenship behavior(β = 0.042), while the controlling climate exerted a significant positive impact on user's citizenship behavior (β = 0.078) and user's participation behavior(β = 0.099); (2) The need for achievement played a suppressing effect between community climate and user's participation behavior, the need for power played a suppressing effect between supportive climate and user's value co-creation behavior, and the need for affiliation played a mediating role between supportive climate and user's citizenship behavior (β = 0.010) and user's participation behavior(β = 0.006); (3) Community trust positively moderated the relationship between the need for achievement and user's participation behavior(β = 0.058) as well as between the need for power and user's participation behavior(β = 0.043).
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•N-acetyl-l-cysteine-stabilized Ag nanoparticles are synthesized by a chemical reduction method.•The surface plasmon resonance intensity of the silver nanoparticles decreases with ...Fe3+ concentration.•The silver nanoparticles can be used for sensitive and selective detection of Fe3+ ions in water.•A new detection mechanism of oxidation–reduction reaction between Ag NPs and Fe3+ ions is proposed.
We report here a facile colorimetric sensor based on the N-acetyl-l-cysteine (NALC)-stabilized Ag nanoparticles (NALC–Ag NPs) for detection of Fe3+ ions in aqueous solution. The Ag NPs with an average diameter of 6.55±1.0nm are successfully synthesized through a simple method using sodium borohydride as reducing agent and N-acetyl-l-cysteine as protecting ligand. The synthesized silver nanoparticles show a strong surface plasmon resonance (SPR) around 400nm and the SPR intensity decreases with the increasing of Fe3+ concentration in aqueous solution. Based on the linear relationship between SPR intensity and concentration of Fe3+ ions, the as-synthesized water-soluble silver nanoparticles can be used for the sensitive and selective detection of Fe3+ ions in water with a linear range from 80nM to 80μM and a detection limit of 80nM. On the basis of the experimental results, a new detection mechanism of oxidation–reduction reaction between Ag NPs and Fe3+ ions is proposed, which is different from previously reported mechanisms. Moreover, the NALC–Ag NPs could be applied to the detection of Fe3+ ions in real environmental water samples.
Electrolysis of water is regarded as an attractive and feasible way for producing hydrogen. So far, various non‐noble metal nanomaterials have been reported as excellent electrocatalysts for hydrogen ...evolution reaction. Especially, due to the low cost, earth‐abundance and tunable properties, transition metal selenides with different compositions, sizes and structures have been explored broadly as efficient catalysts with the relatively high activities, high stabilities and high efficiencies in full pH range of electrolyte for electrochemical hydrogen evolution reaction. Thus, in this Minireview, after introducing several commonly used electrochemical terms about hydrogen evolution reaction, we mainly focus on various kinds of the transition metal selenides that have been documented as electrocatalysts for hydrogen evolution reaction. Particularly, the merits and demerits of transition metal selenides for hydrogen evolution reaction are systematically discussed. Moreover, we also analyze the encountered challenges and present an outlook for the rapid development of transition metal selenides. We hope this Minireview can bring some fundamental understanding for the readers interested in the transition metal selenides and hydrogen evolution reaction.
Abundant and efficient: Thanks to low cost, earth‐abundance, and tuneable properties, transition metal selenides (TMSs) have been explored as efficient catalysts for electrochemical hydrogen evolution reaction. The advances of the synthesis methods, physical and chemical properties of TMSs for electrocatalysis in hydrogen production has been summarized in this Minireview. Moreover, the application and perspective for TMSs in electrocatalytic hydrogen evolution reaction, including single‐metal selenides and multi‐metal selenides, have been discussed systematically.
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