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1.
ACS Appl Mater Interfaces ; 16(21): 27224-27229, 2024 May 29.
Article in English | MEDLINE | ID: mdl-38745464

ABSTRACT

Transition-metal species embedded in carbon have sparked intense interest in the fields of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, improvement of the electrocatalytic kinetics remains a challenge caused by the synergistic assembly. Here, we propose a biochemical strategy to fabricate the Co nanoparticles (NPs) and Co/Ni-N4-C co-embedded N-doped porous carbon (CoNPs&Co/Ni-N4-C@NC) catalysts via constructing the zeolitic imidazolate framework (ZIF)@yeast precursor. The rich amino groups provide the possibility for the anchorage of Co2+/Ni2+ ions as well as the construction of Co/Ni-ZIF@yeast through the yeast cell biomineralization effect. The functional design induces the formation of CoNPs and Co/Ni-N4-C sites in N-doped carbon as well as regulates the porosity for exposing such sites. Synergy of CoNPs, Co/Ni-N4-C, and porous N-doped carbon delivered excellent electrocatalytic kinetics (the ORR Tafel slope of 76.3 mV dec-1 and the OER Tafel slope of 80.4 mV dec-1) and a high voltage of 1.15 V at 10 mA cm-2 for the discharge process in zinc air batteries. It provides an effective strategy to fabricate high-performance catalysts.

2.
J Colloid Interface Sci ; 669: 146-156, 2024 Sep.
Article in English | MEDLINE | ID: mdl-38713954

ABSTRACT

An in-depth understanding of structure-activity relationship between the phase constitution and solar-to-hydrogen (STH) conversion efficiency is conducive to guiding the optimization route of targeted photocatalyst candidates, further establishing advanced photocatalytic systems. Herein, based on the concept of phase engineering, we encompassed the crystalline phase of CdS and achieved precise regulation of phase proportion as well as phase boundary width in the phase junction for the first time. The above cooperative effect not only modifies energy band distribution for sufficient redox potentials, but also guarantees the reverse migration orientation of photogenerated carriers in phase junction, thereby endowing photocarriers with a prolonged lifetime. Compared to pure cubic or hexagonal phase (72.6 or 101.1 µmol h-1 g-1), this CdS system with optimized phase junction demonstrates an improved photocatalytic hydrogen evolution activity of 1.04 mmol h-1 g-1 and favorable stability without cocatalyst assistance, which mainly stems from an efficient protons reduction process interacting with long-lived photogenerated electrons. This research explores the mechanism behind phase regulation and its relationship with junction capability, providing a powerful strategy to manipulate crystal phase distribution and paving a feasible avenue for other phase-dependent photocatalysts towards rational design of heterostructures based on different phases in solar energy conversion field.

3.
Chem Biodivers ; 21(6): e202400511, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38538539

ABSTRACT

Two undescribed germacrane-type sesquiterpenoids, salcasins A (1) and B (2), together with three known compounds (3-5) were isolated and identified from the whole plant of Salvia cavaleriei var. simplicifolia Stib. The structures of the undescribed compounds were elucidated on the basis of spectroscopic methods, such as HR-ESI-MS, 1D and 2D NMR data. The relative configurations of 1 and 2 were established by analyzing their NOESY spectra as well as by 13C NMR calculations with DP4+ probability analyses. The absolute configurations of 1 and 2 were determined by comparing experimental and calculated ECD spectra. Furthermore, the in vivo anti-Alzheimer's disease activities of 1-5 were evaluated using Caenorhabditis elegans AD pathological model. Among all isolated compounds, salcasin A (1) significantly delayed AD-like symptoms of worm paralysis, which may be a potential anti-AD candidate agent.


Subject(s)
Alzheimer Disease , Caenorhabditis elegans , Salvia , Sesquiterpenes, Germacrane , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Animals , Salvia/chemistry , Caenorhabditis elegans/drug effects , Sesquiterpenes, Germacrane/pharmacology , Sesquiterpenes, Germacrane/chemistry , Sesquiterpenes, Germacrane/isolation & purification , Molecular Structure , Molecular Conformation , Disease Models, Animal
4.
Inorg Chem ; 63(8): 3921-3930, 2024 Feb 26.
Article in English | MEDLINE | ID: mdl-38335732

ABSTRACT

Metal-organic frameworks (MOFs) with multifunctional and tunable optical properties have unique advantages in the field of sensing, and the structure and properties of MOFs are significantly influenced by the ligands. In this study, a Y-type tricarboxylic acid ligand containing amide bonds was synthesized through functional guidance, and three isomorphic and heterogeneous three-dimensional MOFs (Eu-MOF, Tb-MOF, and Gd-MOF) were obtained by solvothermal reaction. Further studies revealed that both the Tb-MOF and Eu-MOF could selectively detect picric acid (PA). The luminescence quenching of the two MOFs by PA was attributed to competing absorption and photoelectron energy transfer mechanisms. In addition, due to the energy transfer between Tb and Rhodamine B, Rhodamine B was encapsulated into Tb-MOF. The obtained material exhibited a linear relationship between the temperature parameters I544/I584 and temperature within the range of 280-400 K, the correlation coefficient (R2) reached an impressive value of 0.999, and the absolute sensitivity of the sample used for temperature sensing was 1.534% K-1. What is more, the material exhibited a good response to trifluoroacetic acid vapor, which suggests the potential of the material for temperature sensing and detection of trifluoroacetic acid vapor. The designed and investigated strategy can also serve as a reference for further research on excellent multifunctional sensors.

5.
Small ; 20(3): e2304784, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37699758

ABSTRACT

Twins in crystal defect, one of the significant factors affecting the physicochemical properties of semiconductor materials, are applied in catalytic conversion. Among the catalysts serving for photocatalytic water splitting, Zn1- x Cdx S has become a hot-point due to its adjustable energy band structure. Via limiting mass transport to control the release rate of anions/cations, twin Zn1- x Cdx S solid solution is prepared successfully, which lays a foundation for the construction of other twin crystals in the future. On twin Zn1- x Cdx S, water tends to be dissociated after being adsorbed by Zn2+ /Cd2+ at twin boundary, then the fast-moving electrons at twin boundary quickly combine with the protons already attached to S2- to form hydrogen. According to the theoretical calculation, not only the intracrystalline electron mobility, but also the extracrystalline capacity of water-adsorption/dissociation and proton-adsorption on the twin boundary are superior to those of the counterpart plane in defect-free phase. The synthetic twin Zn1- x Cdx S apparent quantum efficiency of photocatalysis water splitting for hydrogen reached 82.5% (λ = 420 nm). This research opens up an avenue to introduce twins in crystals and it hopes to shed some light on photocatalysis.

6.
Molecules ; 28(22)2023 Nov 08.
Article in English | MEDLINE | ID: mdl-38005197

ABSTRACT

A pyridine-tricarboxylic acid, 5-(3',5'-dicarboxylphenyl)nicotinic acid (H3dpna), was employed as a adjustable block to assemble a series of coordination polymers under hydrothermal conditions. The seven new coordination polymers were formulated as [Co(µ3-Hdpna)(µ-dpey)]n·nH2O (1), [Zn4.5(µ6-dpna)3(phen)3]n (2), [Co1.5(µ6-dpna)(2,2'-bipy)]n (3), [Zn1.5(µ6-dpna)(2,2'-bipy)]n (4), [Co3(µ3-dpna)2(4,4'-bipy)2(H2O)8]n·2nH2O (5),[Co(bpb)2(H2O)4]n[Co2(µ3-dpna)2(H2O)4]n·3nH2O (6), and [Mn1.5(µ6-dpna)(µ-dpea)]n (7), wherein 1,2-di(4-pyridyl)ethylene (dpey), 1,10-phenanthroline (phen), 2,2'-bipyridine(2,2'-bipy),4,4'-bipyridine(4,4'-bipy),1,4-bis(pyrid-4-yl)benzene (bpb), and 1,2-di(4-pyridyl)ethane (dpea) were employed as auxiliary ligands. The structural variation of polymers 1-7 spans the range from a 2D sheet (1-4, 6, and 7) to a 3D metal-organic framework (MOF, 5). Polymers 1-7 were investigated as heterogeneous catalysts in the Knoevenagel condensation reaction, leading to high condensation product yields (up to 100%) under optimized conditions. Various reaction conditions, substrate scope, and catalyst recycling were also researched. This work broadens the application of H3dpna as a versatile tricarboxylate block for the fabrication of functional coordination polymers.

7.
Article in Chinese | MEDLINE | ID: mdl-36987954

ABSTRACT

Objective:To explore the relationship between sleep status and the disease in children with recurrent vertigo(RVC) by analyzing the objective sleep condition of children with recurrent vertigo. Methods:According to the diagnostic criteria of RVC, 50 children with RVC and 20 normal controls without RVC were selected. According to the vertigo questionnaire score, the RVC group was divided into mild, moderate and severe groups according to severity. Continuous polysomnography(PSG) was performed for all participants, and SPSS 25.0 statistical software was used to analyze the monitoring results. Results:①There were significant differences in sleep time of each period, total sleep time and sleep efficiency between RVC group and control group(P<0.05), but there was no significant difference in sleep latency(P>0.05). The specific manifestations were that the proportion of sleep time in N1 and N2 phases increased, the proportion of sleep time in N3 and REM phases decreased, the total sleep time and sleep efficiency decreased in RVC group. ②The abnormal rate of sleep apnea hypopnea index, that is, the proportion of AHI≥5 times/h and the abnormal rate of lowest blood oxygen saturation in RVC group were higher than those in normal control group. There was significant difference between the two groups(P<0.05). ③There were significant differences in the proportion of AHI≥5 times/h and lowest SpO2 among mild group, moderate group and severe group(P<0.05). ④There was no significant correlation between the degree of vertigo and the abnormal rate of AHI in children with RVC, but there was a negative correlation between the degree of vertigo and the abnormal rate of lowest SpO2 in children with RVC. Conclusion:Children with RVC are often accompanied by sleep disorders, clinicians should pay attention to both the symptoms of vertigo and sleep condition in children. Polysomnography is non-invasive and operable, providing a new idea to the auxiliary examination of RVC in children. It is of certain clinical significance for the comprehensive treatment of children with RVC to actively improve vertigo symptoms and pay attention to improving sleep quality.


Subject(s)
Sleep Apnea, Obstructive , Humans , Child , Polysomnography , Sleep Apnea, Obstructive/diagnosis , Sleep , Dizziness , Vertigo/diagnosis
8.
Materials (Basel) ; 15(24)2022 Dec 09.
Article in English | MEDLINE | ID: mdl-36556598

ABSTRACT

The ultra-wide bandgap semiconductor AlN has attracted a great deal of attention owing to its wide application potential in the field of electronics and optoelectronic devices. In this report, based on the mechanism of the physical vapor transport (PVT) growth of AlN crystal, the c- and m-plane AlN seed crystals were prepared simultaneously through special temperature field design. It is proved that AlN crystals with different orientations can be obtained at the same temperature field. The structure parameter of AlN crystal was obtained through the characteristic evaluations. In detail, XPS was used to analyze the chemical states and bonding states of the surface of seed crystals. The content of oxygen varied along with distinct orientations. Raman spectrum documented a small level of compressive stress on these crystal seeds. Tested results confirmed that the prepared AlN crystal seeds had high quality.

9.
J Colloid Interface Sci ; 626: 544-553, 2022 Nov 15.
Article in English | MEDLINE | ID: mdl-35809443

ABSTRACT

Boron carbonitrides (BCN) have been widely concerned in the field of energy storage and conversion. However, the energy storage mechanism of electrical double-layer behavior and their stacked-layer structure severely limit the improvement of capacitance, thereby hindering their further development in energy storage. Therefore, an ultrasonic-ball milling method was first chosen to obtain BCN nanosheets, together with a feasible way of polyaniline (PANI) modification performed to boost the capacitive reaction of BCN nanosheets. For the first time, a BCN-PANI-based symmetric supercapacitor device can reach a high voltage window of 3.0 V when 1 M Et4N·BF4 was chosen as the electrolyte. The working voltage of 3.0 V is three times that of a device with pure PANI with the ultrahigh energy density of 67.1 W h kg-1, superior to most of the reported PANI-based devices. The eminent electrochemical performance provides a promising strategy to pave the way for configuring carbon-based multiple composite electrodes for other energy storage devices.

10.
J Colloid Interface Sci ; 616: 509-519, 2022 Jun 15.
Article in English | MEDLINE | ID: mdl-35228047

ABSTRACT

The ternary transition metal oxides are promising anode material for lithium-ion batteries (LIBs). However, their practical applications are greatly hindered by the poor conductivity and huge volume changes. To solve the issues, urchin-like inverse spinel manganese (Mn) doped NiCo2O4 hierarchical microspheres were fabricated through a facile hydrothermal approach and subsequent annealing treatment. The as-obtained Mn-doped NiCo2O4 hold microsphere and sharp fiber-shaped needle multilevel nanoscale architecture, which effectively shortened Li ions (Li+) transmission path and improved the conductivity. In addition, the hierarchical urchin-like Mn-doped NiCo2O4 synthesized at annealing temperature (600 °C) manifested a larger capacity and better cycling performance by controlling the crystallinities and morphologies. As expected, it displays an outstanding cycling performance with a reversible capacity of about 945 mAh g-1 after 500 cycles at 2000 mA g-1. The kinetic analysis and galvanostatic intermittent titration technique (GITT) testing also verifies the superior pseudocapacitance contribution and fast elevated ion migration of Li+. Our work provides a promising design to develop suitable anode materials based on transition metal oxides for high-performance LIBs.

11.
J Colloid Interface Sci ; 610: 13-23, 2022 Mar 15.
Article in English | MEDLINE | ID: mdl-34920213

ABSTRACT

Artificial photocatalysis with high-efficiency is a promising route for storing sustainable energy from water splitting. Whereas it is challenging to broaden the solar-spectrum responsive window for harvesting high level of conversion. Herein, based on the band-matching engineering theory, a design of dual S-Scheme heterojunction system is proposed and established in a BP/(Ti3C2Tx@TiO2) composite photocatalyst. The complementary light response region between TiO2 and BP realizes the extension of solar energy utilization over a broad absorption window. Furthermore, this specific band-matching configuration endows spatially long-lived charge carriers with greater accumulation on the divided sub-systems, thereby maintaining the sufficient potential energy capacity associated with excellent photocatalytic properties (H2 evolution rate of 564.8 µmol h-1 g-1 and AQE of 2.7% at 380 nm in pure water). This work describes a promising protocol of designing advanced broadband light-activated photocatalytic systems for solar-chemical energy conversion applications.

12.
Small ; 17(51): e2102899, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34643040

ABSTRACT

Carbon nanomaterials have elicited much research interest in the energy storage field, but most of them cannot be used at high temperatures. Thus, a supercapacitor with high energy and desired stability at high temperatures is urgently required. Herein, BCN nanotubes (BCNNTs) with excellent performance at high temperatures are generated on carbon fibers by optimizing the ratio of B and N. The nanotubes' morphology can effectively alleviate the structural damage caused by the rapid adsorption/desorption of the electrolyte during long-time charge/discharge cycles at high temperatures, thus improving the high-temperature cycle stability. The symmetric supercapacitors that are assembled with the binder-free BCNNT electrode in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM·BF4 ) exhibited a high areal capacitance of 177.1 mF cm-2 at a current density of 5 mA cm-2 , and capacitance retention is maintained up to 86.1% for 5000 cycles at 100 °C. Moreover, the flexible supercapacitor based on BCNNTs in poly(vinylidenefluoride hexafluoropropylene)/EMIM·BF4 /succinonitrile gel electrolyte also exhibits good volumetric capacitance (1.98 mWh cm-3 at a current density of 5 mA cm-2 ) and cycling stability (92.6% retention after 200 charge/discharge cycles) at a temperature of 100 °C. This work shows that binder-free BCNNTs are promising materials for high-temperature flexible energy storage devices.

13.
Nanoscale ; 13(5): 2849-2854, 2021 Feb 07.
Article in English | MEDLINE | ID: mdl-33533782

ABSTRACT

In-depth research on energy storage and conversion is urgently needed; thus, water splitting has become a possible method to achieve sustainable energy utilization. However, traditional carbon material with high graphitization degree exhibits a relatively low electrocatalytic oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activity as it is electrochemically inert. In this work, according to the Lewis theory of acids and bases and the density functional theory (DFT) results, which show that the enriched heteroatom of B/N in the boron carbonitride (BCN) system may introduce stronger adsorption strength of OH*/H2O, respectively, we have designed and synthesized self-supporting BCN materials with different enrichment degrees of B/N (B-BCN/N-BCN) using carbon paper as substrate. Furthermore, by adjusting the contents of B and N, the optimum electrocatalytic performance of overall water splitting was obtained in which the onset voltage of water splitting on B-BCN//N-BCN was lower than 1.60 V. Our strategy of synthesizing materials with different heteroatom enrichment to improve the electronic environment of materials has opened up new opportunities for developing efficient metal-free electrocatalysts.

14.
Ann Transl Med ; 8(20): 1319, 2020 Oct.
Article in English | MEDLINE | ID: mdl-33209899

ABSTRACT

BACKGROUND: Generalized anxiety disorder (GAD) is a common affective disorder characterized by comprehensive anxiety with dysregulation of brain activity which can be reflected by functional magnetic resonance imaging (f-MRI). We aimed to examine abnormal aberrant amplitude low-frequency fluctuation (ALFF) and regional homogeneity (ReHo) in GAD and evaluate their ability to predict treatment remission. METHODS: Using resting-state fMRI (Rs-fMRI), we examined ALFF and ReHo in 30 GAD patients and 30 healthy control (HC) participants. Using on DEPASF4.3 Advanced Edition, voxel-based two-sample t-test analysis was performed on the ALFF and ReHo maps to compare GAD to HC groups, and to compare remitters (n=9) and non-remitters (n=21). Pearson's correlation analysis was used to explore the relationship between baseline Hamilton Anxiety Rating Scale (HAM-A) scores/illness duration and mean ALFF/ReHo values. The severity of GAD symptoms was rated with HAM-A. Remission was defined as HAM-A ≤7 by week 8. RESULTS: Compared to the HC group, GAD patients showed lower ALFF in the right postcentral and right precentral gyrus; lower ReHo in the right precentral, right postcentral, and left precentral gyrus; and higher ReHo in the left posterior cingulate cortex. ALFF values for left postcentral gyrus was negatively correlated with baseline HAM-A, while that of the middle frontal gyrus was positively correlated with baseline HAM-A scores. ReHo value of the left postcentral gyrus was negatively correlated with baseline HAM-A, while that of the right middle frontal gyrus was positively correlated with baseline HAM-A scores. ALFF of the right frontal_superior_orbital and right frontal-medial-orbital cortex was positively correlated with illness duration. ReHo of the left supplementary motor area cortex was negatively correlated with illness duration. Remitters showed higher ALFF in the left hippocampus and higher ReHo value in the right postcentral cortex compared to nonremitters. CONCLUSIONS: These results suggest that altered regional brain activity and local synchronization may be related to the pathophysiology of GAD and have certain value in predicting remission in treatment.

15.
ACS Appl Mater Interfaces ; 12(42): 47425-47434, 2020 Oct 21.
Article in English | MEDLINE | ID: mdl-32975401

ABSTRACT

Lithium-ion capacitors (LICs) have emerged as attractive energy storage devices to bridge the gap between lithium-ion batteries and supercapacitors. While the distinct charge storage kinetics between the anode and the cathode is still a challenge to the widespread application of LICs, the key to improving the energy density of these devices is to widen the operating voltage window and balance the mismatch of the electrode kinetics. To this end, we propose a strategy based on electrostatic attraction by adjusting the B and N atom contents of boron carbonitride (BCN) electrode materials to alter their electronegativities and successfully prepared B-rich and N-rich BCN nanotubes (BCNNTs) via a facile solid-phase synthesis approach. The B-rich BCN (B-BCN) cathode and N-rich BCN (N-BCN) anode noticeably enhance the adsorption of anions and cations, promoting a matching degree between the anode and cathode. In particular, the rationally designed B-BCN//N-BCN LIC achieves a maximum voltage range of 4.8 V, setting a new record for LICs. Furthermore, the energy density reaches up to 200 Wh kg-1 (based on the total mass of cathodic and anodic active materials). Density functional theory calculations provided insight into the mechanism underlying our strategy of widening the voltage range. Our philosophy provides new design guidelines and alternatives for identifying and optimizing high-performance electrodes for energy storage devices.

16.
Small ; 16(13): e1906734, 2020 04.
Article in English | MEDLINE | ID: mdl-32115877

ABSTRACT

Large-size ultrathin 2D materials, with extensive applications in optics, medicine, biology, and semiconductor fields, can be prepared through an existing common physical and chemical process. However, the current exfoliation technologies still need to be improved upon with urgency. Herein, a novel and simple "ultrasonic-ball milling" strategy is reported to effectively obtain high quality and large size ultrathin 2D materials with complete lattice structure through the introduction of moderate sapphire (Al2 O3 ) abrasives in a liquid phase system. Ultimately numerous high-quality ultrathin h-BN, graphene, MoS2 , WS2 , and BCN nanosheets are obtained with large sizes ranging from 1-20 µm, small thickness of ≈1-3 nm and a high yield of over 20%. Utilizing shear and friction force synergistically, this strategy provides a new method and alternative for preparing and optimizing large size ultrathin 2D materials.


Subject(s)
Materials Science , Nanostructures , Ultrasonics , Friction , Graphite , Materials Science/methods , Nanostructures/chemistry , Shear Strength
17.
Chemistry ; 25(44): 10420-10426, 2019 Aug 06.
Article in English | MEDLINE | ID: mdl-31140645

ABSTRACT

The anisotropy of crystalline materials results in different physical and chemical properties on different facets, which warrants an in-depth investigation. Macroscopically facet-tuned, high-purity gallium nitride (GaN) single crystals were synthesised and machined, and the electrocatalytic hydrogen evolution reaction (HER) was used as the model reaction to show the differences among the facets. DFT calculations revealed that the Ga and N sites of GaN (100) had a considerably smaller ΔGH* value than those of the metal Ga site of GaN (001) or N site of GaN (00-1), thereby indicating that GaN (100) should be more catalytically active for the HER on account of its nonpolar facet. Subsequent experiments testified that the electrocatalytic performance of GaN (100) was considerably more efficient than that of other facets for both acidic and alkaline HERs. Moreover, the GaN crystal with a preferentially (100) active facet had an excellently durable alkaline electrocatalytic HER for more than 10 days. This work provides fundamental insights into the exploration of the intrinsic properties of materials and designing advanced materials for physicochemical applications.

18.
Adv Mater ; 31(10): e1806088, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30637832

ABSTRACT

The use of transition-metal oxide (TMO) as an extended-life electrochemical energy storage material remains challenging because TMO undergoes volume expansion during energy storage. In this work, a transition-metal oxynitride layer (TMON, M: Fe, Co, Ni, and V) was synthesized on TMO nanowires to address the crucial issue of volume expansion. The unique oxynitride layer possesses numerous active sites, excellent conductivity, and outstanding stability. These characteristics enhance specific capacitance and alleviate volume expansion effectively. Specifically, the specific capacity of the TMON electrode is enhanced by approximately twofold relative to that of its corresponding oxide. Notably, the capacitance of the TMON remains above 94% even after 10 000 cycles. This result indicates that the cycling performance of the TMON electrode is superior to that of its corresponding oxide. First-principles and quantitative kinetics analyses are performed to investigate the mechanism underlying the improved electrochemical performances of the TMON layers. Results demonstrate that the proposed TMON layer has attractive applications in the fields of energy storage, conversion, and beyond.

19.
ChemSusChem ; 12(9): 2008-2014, 2019 May 08.
Article in English | MEDLINE | ID: mdl-30329216

ABSTRACT

Phase engineering has been demonstrated as an efficient method for the enhancement of catalytic activity. This study concerns the phase and morphology modulation of Ni3 Se2 /NiSe nanorod arrays through a hydrothermal process. Partial phase conversion can effectively enhance the electrical conductivity and yield more active sites through atom rearrangement during phase transformation. Quite low optimal overpotentials of 166 mV for the hydrogen evolution reaction (HER) and 370 mV for the oxygen evolution reaction (OER) are obtained in a sample containing 32.4 % of NiSe phase and 67.6 % of Ni3 Se2 phase. The performance is superior to the samples with only one phase. Furthermore, a water electrolyzer was assembled by using two symmetrical NiSe/Ni foam electrodes as the anode and cathode, which can deliver 10 mA cm-2 at a low voltage of 1.61 V. More significantly, the water electrolyzer can be operated at 10 mA cm-2 over 10 h without noticeable degradation, showing extraordinary operational stability. This phase conversion control strategy provides a new way to improve the catalytic activity of NiSe and may have potential use in the design of other selenide electrocatalysts.

20.
ChemSusChem ; 11(18): 3198-3207, 2018 Sep 21.
Article in English | MEDLINE | ID: mdl-30010250

ABSTRACT

Faceted nanomaterials with highly reactive exposed facets have been the target of intense researches owing to their significantly enhanced catalytic performance. NiMoN nanowires with the (100) facet preferentially exposed were prepared by an in situ N/O exchange and the morphology tuned by using a rationally designed NiMoO4 precursor. The facet-tuned NiMoN nanowires exhibited excellent electrocatalytic activity for the hydrogen evolution reaction (HER) under both alkaline and acidic conditions that was comparable to that of noble metal platinum. DFT calculations further revealed that the catalytic activity of NiMoN nanowires towards HER on the (100) reactive facet is significantly greater than that on the (001) or (101) facets, owing to the low adsorption free energy of H* (ΔGH* ) on the (100) facet. The NiMoN nanowires also demonstrated outstanding activity towards the alkaline oxygen evolution reaction and an excellent durable activity for overall water splitting, with a cell potential as low as 1.498 V at 20 mA cm-2 . This work provides insights into improving electrocatalytic activity and developing advanced non-noble metal bifunctional electrocatalysts.

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