Developing highly active and low-cost heterogeneous catalysts toward overall electrochemical water splitting is extremely desirable but still a challenge. Herein, we report pyrite NiS2 nanosheets doped with vanadium heteroatoms as bifunctional electrode materials for both hydrogen- and oxygen-evolution reaction (HER and OER). Notably, the electronic structure reconfiguration of pyrite NiS2 is observed from typical semiconductive characteristics to metallic characteristics by engineering vanadium (V) displacement defect, which is confirmed by both experimental temperature-dependent resistivity and theoretical density functional theory calculations. Furthermore, elaborate X-ray absorption spectroscopy measurements reveal that electronic structure reconfiguration of NiS2 is rooted in electron transfer from doped V to Ni sites, consequently enabling Ni sites to gain more electrons. The metallic V-doped NiS2 nanosheets exhibit extraordinary electrocatalytic performance with overpotentials of about 290 mV for OER and about 110 mV for HER at 10 mA cm–2 with long-term stability in 1 M KOH solutions, representing one of the best non-noble-metal bifunctional electrocatalysts to date. This work provides insights into electronic structure engineering from well-designed atomic defect metal sulfide.Keywords: defect engineering; electronic structure; metallic characteristics; water splitting; X-ray absorption spectroscopy;

We demonstrate a heterostructure Ni9S8/MoS2 hybrid with tight interface synthesized via an improved hydrothermal method. As compared to pure MoS2, the increased surface area and the shorten charge transport pathway in the layered hybrid significantly promote the photocatalytic efficiency for hydrogen evolution reaction (HER). In particularly, the optimized Ni9S8/MoS2 hybrid with 20 wt % Ni9S8 exhibits the highest photocatalytic activity with HER value of 406 μmolg–1h–1, which is enhanced by 70% compared to that of pure MoS2 nanosheets (285.0 μmolg–1h–1). Moreover, the value is 4 times more than the commercial MoS2 (92.0 μmolg–1h–1), indicating the high potential of the hybrid in the catalytic fields.

Two-dimensional stable metallic 1T-MoSe2 with expanded interlayer spacing of 10.0 Å in situ grown on SWCNTs film is fabricated via a one-step solvothermal method. Combined with X-ray absorption near-edge structures, our characterization reveals that such 1T-MoSe2 and single-walled carbon nanotubes (abbreviated as 1T-MoSe2/SWCNTs) hybridized structure can provide strong electrical and chemical coupling between 1T-MoSe2 nanosheets and SWCNT film in a form of C–O–Mo bonding, which significantly benefits a high-efficiency electron/ion transport pathway and structural stability, thus directly enabling high-performance lithium storage properties. In particular, as a flexible and binder-free Li-ion anode, the 1T-MoSe2/SWCNTs electrode exhibits excellent rate capacity, which delivers a capacity of 630 mAh/g at 3000 mA/g. Meanwhile, the strong C–O–Mo bonding of 1T-MoSe2/SWCNTs accommodates volume alteration during the repeated charge/discharge process, which gives rise to 89% capacity retention and a capacity of 971 mAh/g at 300 mA/g after 100 cycles. This synthetic route of a multifunctional MoSe2/SWCNTs hybrid might be extended to fabricate other 2D layer-based flexible and light electrodes for various applications such as electronics, optics, and catalysts.Keywords: 1T-MoSe2 nanosheets; carbon nanotube; flexible electrode; layered hybrid; lithium-ion battery;

Designing advanced electrocatalysts for hydrogen evolution reaction is of far-reaching significance. Active sites and conductivity play vital roles in such a process. Herein, we demonstrate a heteronanostructure for hydrogen evolution reaction, which consists of metallic 1T-MoS2 nanopatches grown on the surface of flexible single-walled carbon nanotube (1T-MoS2/SWNT) films. The simulated deformation charge density of the interface shows that 0.924 electron can be transferred from SWNT to 1T-MoS2, which weakens the absorption energy of H atom on electron-doped 1T-MoS2, resulting in superior electrocatalytic performance. The electron doping effect via interface engineering renders this heteronanostructure material outstanding hydrogen evolution reaction (HER) activity with initial overpotential as small as approximately 40 mV, a low Tafel slope of 36 mV/dec, 108 mV for 10 mA/cm2, and excellent stability. We propose that such interface engineering could be widely used to develop new catalysts for energy conversion application.

The search for new electrode materials is of paramount importance for the practical apply of lithium-ion batteries (LIBs). Herein, flower-like MoO2 microislands consist of MoO2 nanorods grown on both sides of graphene sheets were synthesized via a solvo-thermal method, followed by a simple thermal treatment in argon. Our EXAFS and ESR data suggest there oxygen-vacancies in MoO2 of the FMMGS hybrids. Besides, by tunning the ratio of glucose and CTAB, samples with different oxygen-vacancies content were synthesized. When used as anode materials for lithium-ion batteries, the oxygen-vacancy-rich FMMGS hybrids exhibited obviously higher capacity, rate capability than any nonvacancy samples. Importantly, synchrotron-radiation-based X-ray absorption near-edge structure (XANES), extended X-ray absorption fine-structure (EXAFS) and ex situ X-ray diffraction (ex situ XRD) were employed to elucidate the Li-ion insertion and extraction processes in the MoO2 electrode. Our data clearly revealed that Li2MoO4 was generated during the Li uptake/removal process, which can be attributed to the existence of abundant oxygen vacancies in MoO2 microislands. This provides us a useful insight for better understanding of dynamic cycling behavior in various Mo-based electrodes.

The role of transition-metal d and ligand p hybridization continues to be of immense interest in Li-ion battery cathode, and yet it is still poorly understood. Using combined experimental and theoretical soft X-ray absorption spectroscopic study and density functional theory calculation, we investigated the fundamental electronic structure of the high-voltage spinel LiNixMn2–xO4. An oxygen-participating charge rebalance between manganese and nickel ions was found; that is, the content of O 2p holes close to the Fermi level increases along with the increasing Ni content. Moreover, these unstable oxygen holes primarily congregate around the redox active dopants. The underlying mechanism accounting for this charge-compensated occurrence is the reverse of two bonding levels when manganese ions are oxidized from +3 to +4 states. On the basis of these new findings, we further exposed the role of oxygen in electrochemical performance. First, oxygen ions afford the charge variation together with the cations during Li insertion/deinsertion process. Second, the O 2p holes can largely screen the strong electrostatic repulsion between Mn4+ and Li+ ions to effectively enhance the rate capacity. Lastly, the excessive amount of O 2p holes is disadvantageous to the thermal stability associated with the O2 evolution. Also, we point out that O 2p holes concentration can be modified by the metal–oxygen bonding character, and the “charge-transfer energy” is a crucial point for designing high-capacity positive electrodes for Li-ion battery.

Thin, planar nanojunctions between layered 2H/1T-MoS2 and graphitic C3N4 (g-C3N4) were fabricated and 1T phase nanojunctions allowed faster photogenerated electrons across the junction interfaces to facilitate hydrogen evolution. This research represents a proof of concept for the rational fabrication of thin 1T phase interfacial junctions and the importance of the 1T phase for further improving the HER perfomance.

Designing Prussian blue with optimally exposed crystal planes and confining it in a conductive matrix are critical issues for improving its sodium storage performance, and will result in much improved sodium ion adsorption and diffusion, together with improved electron mobility. Here, we firstly illustrate through DFT simulations that the {100} lattice planes and [100] direction of the KxFeFe(CN)6 crystal are the preferred occupation sites and diffusion route for sodium ions. In addition, through coupling with RGO, KxFeFe(CN)6 electrodes exhibit better electronic conductivity. Accordingly, {100} plane-capped cubic K0.33FeFe(CN)6 wrapped in RGO was fabricated using a facile CTAB-assisted method. Due to the highly robust framework, higher specific surface area, greatly reduced number of lattice water defects and conductive RGO coating, K0.33FeFe(CN)6/RGO exhibits superior electrochemical performance in sodium-ion batteries. As a cathode, the RGO-coated K0.33FeFe(CN)6 yields an initial discharge–charge capacity of 160 mA h g−1 at a rate of 0.5C, and an excellent capacity retention of 92.2% at 0.5C and 90.1% at 10C after 1000 and 500 cycles. Furthermore, XRD, DFT simulation, XANES and EXAFS verified that the structural changes during the Na-ion insertion–extraction processes are highly reversible. All these results suggest that {100} plane-capped K0.33FeFe(CN)6/RGO has excellent potential as a cathode for sodium-ion batteries.

Two-dimensional layered structure of a single crystal is regarded as an ideal feature for physical and chemical fundamental studies. Herein, we demonstrated a high-quality (NH4)2V3O8 single crystal with a layered tetragonal structure prepared via a hydrothermal method. The lattice vibrational behavior and surface electronic state of (NH4)2V3O8 layers were systematically investigated via polarized Raman scattering spectroscopy and ultraviolet photoelectron spectroscopy (UPS), respectively. It was found that all Raman peaks of (NH4)2V3O8 could be clearly identified as four active Raman modes through parallel and perpendicular polarization configurations in the backscattering geometry for (001) crystal surface. The UPS results indicated that the valence band maximum of (NH4)2V3O8 was mainly composed of localized vanadium 3d states, which was further confirmed by the density functional theory calculations.

Ultrafine noble metal nanoparticles decorated on onion-like carbon (OLC) were successfully prepared without any reductant or surfactant. Particularly, the as-prepared Pt–OLC nanocomposite not only exhibited superior electrocatalytic activity and stability for the hydrogen evolution reaction as compared with the commercial 20% Pt/C, but also showed enhanced supercapacitor performance with a specific capacitance almost four times larger than that of OLC. Notably, the C–O functional groups on the surface of OLC will increase after the reaction because of the oxidation by O2 and chloroplatinic acid, which is very useful for the reuse of OLC and helpful for the decoration of noble metal nanoparticles on OLC. This work provides a simple and straightforward method for the facile preparation of metal composite nanocatalysts with high catalytic activity.

•Simple solid-state reaction to synthesize stable rock-salt oxides.•Ni substitution of precious Ru offers multiple electron redox.•Peroxide structure and 0-TM percolation network dramatically enhance performance.•Li1.23Ni0.155Ru0.615O2 exhibits a discharge capacity of 295.3 mAh g−1.Peroxide structure O2n− has proven to appear after electrochemical process in many lithium-excess precious metal oxides, representing extra reversible capacity. We hereby report construction of a Li-excess rock-salt oxide Li1+xNi1/2-3x/2Ru1/2+x/2O2 electrode, with cost effective and eco-friendly 3d transition metal Ni partially substituting precious 4d transition metal Ru. It can be seen that O2n− is formed in pristine Li1.23Ni0.155Ru0.615O2, and stably exists in subsequent cycles, enabling discharge capacities to 295.3 and 198 mAh g−1 at the 1st/50th cycle, respectively. Combing ex-situ X-ray absorption near edge spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, high resolution transmission electron microscopy and electrochemical characterization, we demonstrate that the excellent electrochemical performance comes from both percolation network with disordered structure and cation/anion redox couples occurring in charge-discharge process. Li-excess and substitution of common element have been demonstrated to be a breakthrough for designing novel high performance commercial cathodes in rechargeable lithium ion battery field.Download high-res image (326KB)Download full-size image

Layered transition metal disulfides are currently being widely studied for advanced energy generation and storage applications. Here we report a facile template-assisted solvothermal strategy to obtain a hierarchical nanotubular structure consisting of ultrathin MoS2 nanosheets with a metallic 1T phase. Synchrotron radiation based X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) are used to investigate the structure and electronic properties of the 1T-MoS2, which are largely different from annealed samples. Its hierarchical structure makes the obtained nanotubular 1T-MoS2 an excellent electrode material for supercapacitors, with a high specific capacitance of 328.547 F g−1 at a current density of 1 A g−1 and 243.66 F g−1 at a current density of 15 A g−1. Moreover, the material displays excellent capacitance retention, retaining 98.4% capacity after 5000 cycles at a current density of 3 A g−1. Notably, a high specific capacitance of 250 F g−1 at 1 A g−1 is also achieved in a two-electrode symmetrical cell, suggesting its great potential for new-generation supercapacitors.

We present high quality WX2 (X = S, Se) single crystals synthesized via an improved chemical vapor transport technique. Morphological and structural characteristics of the as-grown layered single crystals were analyzed using SEM, TEM, XPS, Raman spectroscopy, XRD and UV visible spectroscopy characterization techniques. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge-discharge analysis reveal the insights for WX2 single crystals to be used an as excellent material for electrochemical supercapacitors. Notably the obtained supercapacitor electrodes show excellent cycle stability and high capacitance retention of 80 and 99% for WS2 and WSe2 respectively after 20,000 cycles, suggesting their high potential in electrochemical energy storage applications.Download high-res image (315KB)Download full-size image

Developing flexible electrode is essential for new generation wearable electronics and energy devices. Combining with membrane-assisted vacuum filtration, highly flexible and stable hybridized electrodes, containing of S-doped graphene, carbon nano-onion (OLC) and Ni3S2 composite (GCNi3S2) are obtained. X-ray absorption characterizations reveal the transfer of electrons from C to Ni atoms due to the tight interface between Ni3S2 and GO/OLC, indicating the synergistic effect on fast redox reaction and ultrashort ion diffusion pathway among the hybrid electrodes. The assembled flexible symmetrical all-solid-state supercapacitor exhibits high volumetric capacitance of 55.3 F cm−3, along with an outstanding energy density of 3.63 Wh cm−3 and excellent stability of 5000 cycles with 97.2% capacitance remaining. The bending tests further confirm outstanding flexible performance in the capacitor device. Moreover, the assembled micro supercapacitor with GCNi3S2 electrode indicates the advantage of this membrane-assisted assembled strategy for easily realizing various flexible films as multitype supercapacitor's electrode which is otherwise difficult for powder-like materials.Download high-res image (303KB)Download full-size image

The hydrogen evolution reaction (HER) may contribute substantially to energy resources in the future through solar energy conversion. In this study, mesoporous graphitic carbon nitride (g-C3N4) layers modified by detonation nanodiamond (DND) were synthesized by condensation from urea to obtain a robust and efficient hybrid (g-C3N4–DND) photocatalyst for the HER. Our characterizations revealed that no significant structural changes occurred in g-C3N4 during the synthesis of the g-C3N4–DND hybrid. Compared with pure g-C3N4, hydrogen production increased by almost 50% when using the hybrid photocatalyst due to the synergetic effect of the enhanced charge transfer, high surface area and low recombination rate of the photogenerated charge carriers.

Vertical 1T-MoS2 nanosheets with an expanded interlayer spacing of 9.8 Å were successfully grown on a graphene surface via a one-step solvothermal method. Such unique hybridized structures provided strong electrical and chemical coupling between the vertical nanosheets and graphene layers by means of C–O–Mo bonding. The merits are very beneficial for a high-efficiency electron/ion transport pathway and structural stability. As a proof of concept, the lithium ion battery with the as-obtained hybrid's electrode exhibited excellent rate performance with a 666 mA h g−1 capacity at a high current density of 3500 mA g−1. We can extend this method to produce various metallic 1T-MX2 (M = transition metal; X = chalcogen) vertically edged on a graphene frame as one of the promising hetero-structures for several specific applications in the fields of electronics, optics and catalysis.

Here we demonstrate a ternary Cu2NiZn alloy substrate for controllably synthesizing monolayer graphene using a liquid carbon precursor cyclohexane via a facile CVD route. In contrast with elemental metal or bimetal substrates, the alloy-induced synergistic effects that provide an ideal metallic platform for much easier dehydrogenation of hydrocarbon molecules, more reasonable strength of adsorption energy of carbon monomer on surface and lower formation energies of carbon chains, largely renders the success growth of monolayer graphene with higher electrical mobility and lower defects. The growth mechanism is systemically investigated by our DFT calculations. This study provides a selective route for realizing high-quality graphene monolayer via a scalable synthetic method by using economic liquid carbon supplies and multialloy metal substrates.Keywords: alloy; chemical vapor deposition; density functional theory; graphene; growth mechanism;

A room-temperature ferromagnetic behavior was observed in a ternary layered-Cu2MoS4 nanosheet. Both the coercivity and magnetization saturation increased with a decrease in temperature. The electron paramagnetic resonance spectroscopy confirmed a high g value. Combined with atomic structural observations, our first principle calculations revealed that the ferromagnetism originated from the edged molybdenum atoms.

Layered Cu2MoS4, consisting of earth-abundant elements, is regarded as a potential catalyst for the hydrogen evolution reaction (HER). Herein, we demonstrate a Cu2O-based template strategy to synthesise hierarchical hollow nanostructures of Cu2MoS4. The characterizations reveal that the electrochemically active surface of the hollow Cu2MoS4 is largely enhanced, in contrast to the nanosheet or nanoparticle structures. As the direct outcome, the designed hierarchical hollow structures display excellent HER activities with a low overvoltage and small Tafel slope. This study may provide new inspiration for the research of other ternary sulphide materials as well as subsequently accelerating their applications in the field of catalysis.

•The wafer-size free-standing SWNTs/VO2/Mica hierarchical film were prepared.•The infraredtransmission of the film was facilely modulated by external voltage.•The energy barrier to trigger MITwas decreasedfor practical applications.Vanadium dioxide (VO2) with reversible metal-insulator transition (MIT) is a promising energy-saving material for next-generation smart windows and infrared devices. However, the specific applications are largely limited by the relatively high critical temperature as well as the non-transferable grown-substrate. Herein, we report such limitations can be overcome by directly growing VO2 on layered mica sheets and integrating with high transparent single-walled carbon nanotube (SWNT) films. The SWNTs/VO2/mica hierarchical films can be peeled-off to form a free-standing ultra-thin optical window and can further be transferred to other substrates with high flexibility and transparency. By heating the SWNTs/VO2 layer with a bias current, the MIT process of VO2 film can be facilely modulated, achieving the reversible and dynamical regulation of the infrared transmission. Furthermore, by adjusting the bias current, it is possible to change the starting local temperature and shift the initial situation close to the “phase transition boundary”, resulting in the decreased energy barrier to trigger the MIT behavior. This fascinating strategy overcomes the high critical temperature limit of VO2 and avoids the bottle-neck problem in practical applications of VO2 material, which demonstrates wide applications of this kind of device in the future.

Graphene-based materials have exhibited high potential for applications in the field of energy generation and storage because of its high surface area and porosity. Herein, we present a facile strategy to assemble graphene/carbon nanotubes into well-dispersed three-dimensional sponge and subsequently cut nano-scale pores via nickel nanoparticles for enhancing anode’s performance in lithium-ion batteries. Our characterizations reveal that the hybrid aerogels exhibit a lot of nanoscale channels and pores due to the Ni-nanocutting process, resulting in an improved specific surface area 254 m2/g in contrast with 187 m2/g for the pristine materials. The hybrid aerogels are subsequently used as anode for lithium-ion battery and exhibit a greatly improved performance after nanocutting treatment. Meanwhile, the specific capacity of supercapacitor with the Ni-cutting aerogel electrode can achieve as high as 475 F/g, which is almost 68 times than that of the pure material (7 F/g). This route may open a facile engineering way to produce porous and high performance electrode for specific electrochemical applications.

Layered tungsten disulfide (WS2) has attracted great attention because of its high potential for electrochemical energy applications. However, the semiconducting nature of WS2 with a 2H phase largely hinders its electrochemical performance due to poor electronic conductivity. In this study, we have successfully synthesized a metallic 1T-WS2 nanoribbon with stable ammonia-ion intercalation as a highly conductive electrode for high-performance supercapacitors. The specific capacitance using the metallic 1T-WS2 electrode exhibits significant enhancement upto the value of 2813 μF cm−2. This value is 12 times higher compared to semiconducting 2H-WS2. Moreover, the 1T-WS2 electrode has good stability even under high current scans, which is ascribed to the stable ammonia-ion interaction. The correlation between the 1T-WS2 structure and its electrochemical performance has also been discussed.

Na3V2(PO4)3 (NVP) has been in the spotlight as a potential candidate of next generation batteries to overcome the limitation of lithium resources on Earth. Here a thin-layer graphene-encapsulated NVP composite (NVP/G) was synthesized by self-assembly of surface modified NVP and graphene oxide and then followed by reduction to compensate for the intrinsic low electronic conductivity of NVP and strengthen its structure stability. The as-synthesized hybrid composite as a cathode for sodium-ion batteries (SIBs) exhibits excellent high specific capacity and superior rate performance with discharge capacities of 115.2 mA h g−1 at 0.2 C and 70.1 mA h g−1 at 30 C, It also shows an excellent cycling stability with about 86.0% capacity retention at 5 C after 300 cycles. Ex situ X-ray absorption spectroscopy (XAS) characterization confirmes the local geometrical environment around vanadium is highly conserved during the sodiation/desodiation process, associated with an electrochemically active V3+/V4+ redox couple. Hence the as-prepared hybrid composite can be considered as a promising cathode material for high-rate SIBs, thanks to the effect interface interaction between NVP nanoparticle sand graphene films.

Understanding the intrinsic relationship between the catalytic activity of bimetallic nanoparticles and their composition and structure is very critical to further modulate their properties and specific applications in catalysts, clean energy, and other related fields. Here we prepared new bimetallic Pt–Ru nanoparticles with different Pt/Ru molar ratios via a solvothermal method. In combination with X-ray diffraction (XRD), transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and synchrotron X-ray absorption spectroscopy (XAS) techniques, we systematically investigated the dependence of the methanol electro-oxidation activity from the obtained Pt/Ru nanoparticles with different compositions under annealing treatment. Our observations revealed that the Pt–Ru bimetallic nanoparticles have a Pt-rich core and a Ru-rich shell structure. After annealment at 500 °C, the alloying extent of the Pt–Ru nanoparticles increased, and more Pt atoms appeared on the surface. Notably, subsequent evaluations of the catalytic activity for the methanol oxidation reaction proved that the electrocatalytic performance of Pt/Ru bimetals was increased with the oxidation degree of superficial Ru atoms.

We present a controllable synthesis of ternary hierarchical hollow sphere, assembling by numerous particle-like Cu2MoS4, via a facile hydrothermal method. By adding graphene oxides (GO) in the reaction process, Cu2MoS4/reduced graphene oxide (RGO) heterostructures were obtained with enhanced photocurrent and photocatalytic performance. As demonstrated by electron microscopy observations and X-ray characterizations, considerable interfacial contact was achieved between hierarchical Cu2MoS4 hollow sphere and RGO, which could facilitate the separation of photoinduced electrons and holes within the hybrid structure. In comparison with the pure Cu2MoS4 hollow sphere, the obtained hybrid structures exhibited significantly enhanced light absorption property and the ability of suppressing the photoinduced electron–holes recombination, which led to significant enhancement in both photocurrent and efficiency of photocatalytic methyl orange (MO) degradation under visible light (λ > 420 nm) irradiation.

Herein, we report a bottom-up solvothermal route to synthesize a flexible, highly efficient MoS2@SWNT electrocatalyst for hydrogen evolution reactions (HER). Characterization revealed that branch-like MoS2 nanosheets containing sulfurrich sites were in situ uniformly dispersed on free-standing single-walled carbon nanotube (SWNT) film, which could expose more unsaturated sulfur atoms, allowing excellent electrical contact with active sites. The flexible catalyst exhibited excellent HER performance with a low overpotential (~150 mV at 10 mA/cm2) and small Tafel slope (41 mV/dec). To further explain the improved performance, the local electronic structure was investigated by X-ray absorption near-edge structure (XANES) analysis, proving the presence of unsaturated sulfur atoms and strong electronic coupling between MoS2 and SWNT. This study provides an in-situ synthetic route to create new multifunctional flexible hybridized catalysts and useful insights into the relationships among the catalyst microstructure, electronic structure, and properties.

Understanding the detailed reaction mechanism in the early stage of noble metal nanoparticles is very critical for controlling the final crystal’s size, morphology, and properties. Here, we report a systematic study on the initial reaction mechanism of Pt nanoparticles in methanol–water system and demonstrate an anomalous catalytic effect of H2O on the reduction of H2PtCl6 to Pt nanoparticles using a combination of UV–vis, X-ray absorption spectroscopy (XAS), liquid chromatography mass spectrometry (LCMS), and first-principles calculation methods. The observations reveal the transformation route [PtCl6]2– → [PtCl5(CH3O)]2– → [PtCl4]2– → [PtCl3(CH3O)]2– → [PtCl2]2– and finally to form Pt nanoparticles in a pure CH3OH solution. With 10 vol % water adding in the CH3OH solution, a new and distinct chemical reduction pathway is found in which the precursors change from [PtCl6]2– to [PtCl5(CH3O)(H2O)]2– to [PtCl4]2– to [PtCl3(CH3O)(H2O)]2– to [PtCl2]2– and to Pt nanoparticles. Notably, the supernumerary water molecular can significantly accelerate the rate of chemical reduction and greatly shorten the reaction time. This work not only elucidates the initial reaction mechanism of Pt nanoparticles but also highlights the pronounced influence of H2O on the reaction pathway, which will provide useful insights for understanding the formation mechanism of noble metal nanoparticles and open up a high efficient way to synthesize new functional nanomaterial.

We demonstrate ultrathin self-assembled Cu2MoS4 nanobelts synthesized by using Cu2O as the starting sacrificial template via a hydrothermal method. The nanobelts exhibit strong light absorption over a broad wavelength spectrum, suggesting their potential application as photocatalysts. The photocatalytic activity of nanobelts is evaluated by the degradation of Methyl Orange (MO) dye under visible light irradiation. Notably, the nanobelts can completely degrade 100 mL of 15 mg mL−1 MO in 20 minutes with excellent recycling and structural stability, suggesting their excellent photocatalytic performance. In comparison with a sheet-like sample, the high efficiency of the self-assembled Cu2MoS4 nanobelts is attributed to a high surface area and a unique band gap, agreeing with the nitrogen adsorption analysis and photoluminescence spectra. This study offers a self-assembled synthetic route to create new multifunctional nanoarchitectures composed of atomic layers, and thus may open a window for greatly extending potential applications in water pollution treatment, photocatalytic water-splitting, solar cells and other related fields.

Carbon layer-coated molybdenum dioxide nanoparticles exhibit strong photo-absorption in the near infrared (NIR) region with good photostability. The in vitro and in vivo experiments reveal that an excellent photothermal ablation induced from the nanoparticle agents under NIR irradiation can kill tumor cells not only at the cellular level but also in living organs.

The aim of this study is the potential use of nanodiamond to make the lightweight and strong nanocomposites. Here, effects of size and surface modification of detonation nanodiamond (DND) on mechanical performance of epoxy based nanocomposites is presented. Our characterizations reveal that the process of functionalization not only removes the non-diamond content and impurities by significantly reducing DND's size but also introduces oxygen containing functional groups on its surface. The average size of functionalized DND aggregations could be decreased from 300 to 100 nm in contrast to pristine DND, which greatly benefits its homogeneous dispersion in epoxy matrix. In addition, strong chemical bonding among functionalized DND and epoxy resin due to functional groups leads to the formation of efficient interface. These interfaces overlap at high concentrations making a network which in turn significantly enhances the tensile properties. The enhancement in Young's modulus can reach up to 2.5 times higher than that of neat epoxy whereas the enhancement in tensile strength is about 1.5 times in functionalized DND/epoxy nanocomposites.

The predicted extraordinary properties of carbon nanotubes (CNTs) from theoretical calculations have great potential for many applications. However, reliable experimental determination of intrinsic properties at the single-tube level is currently a matter of concern, and many challenges remain because of the unhandled and nanoscale size of individual nanotubes. Here, we demonstrated a prototype to detect the intrinsic thermal conductivity of the single-wall carbon nanotube (SWCNT) and verify the significant non-resonant optical absorption behavior on tiny nanotubes by integrating the nanotube and ice into a new core-shell design. In particular, a reversible optical visualization method based on the individual suspended ultra-long SWCNT was first developed by wrapping a nanotube with ice in the cryogenic air environment. The light-induced thermal effect on the hybrid core-shell structure was used to melt the ice shell, which subsequently acted as a temperature sensor to verify the intrinsic thermal conductivity of the core-like nanotube. More interestingly, we successfully determined for the first time the thermal response phenomenon of the tiny absorption cross section in SWCNT in the vertical-polarization configuration and the significant non-resonant absorption behavior in the parallel-polarization configuration. These investigations will provide a better understanding for the unique optical behaviors of CNT and enable the detection of intrinsic properties of various one-dimensional nanostructures such as nanotubes, nanowires, and nanoribbons.

We present a new olivine LiFePO4(LFP)@C/reduced graphene oxide(RGO) nanocomposite synthesized by a solvothermal method. In this hybrid nanocomposite, the cooperation of the LiFePO4 with a carbon coating and the reduction of the graphene oxide has been tuned to produce an effective three-dimensional (3D) conductive network. Compared with conventional LFP@C nanocomposites, the experimental results of LFP@C/RGO nanocomposites show their outstanding electrochemical performance with higher rate capability and better cycability. In particularly, no obvious capacity fading after 200 cycles at a current of 10 C is observed and a discharge capacity of 119 mAh/g can be still delivered at 20 C, pointing out that the electronic conductivity of electrode particles also contribute to achieve a high-rate performance. This study may play a key role in large power sources when applied in industrial productions, such as electric vehicles.

Olivine-type LiFe1–xMnxPO4 compounds were systematically synthesized by a solvothermal method. Synchrotron radiation X-ray absorption spectroscopy combined with first-principles calculations and energy-dispersive X-ray spectroscopy measurements show that the as-prepared LiFe1–xMnxPO4 samples contain two different phases: LiFePO4 and LiMnPO4. Actually, due to the crystal field effect, these two structures are randomly stacked and characterized by a pronounced structural distortion of the MO6 (M: Fe or Mn) octahedra. Moreover, increasing the Mn doping concentration, the distortion of the MO6 octahedra increases. Considering the size of LiMnPO4 stacks and the distortion of MO6 octahedra, the best performance occurs at the optimal Mn doping concentration. Among the different Fe/Mn ratios, the electrochemical tests show that the as-prepared LiFe0.75Mn0.25PO4 sample exhibits the best electrochemical performance. Moreover, in order to optimize electrochemical performances, data point out that the doping procedure may control the size of the LiMnPO4 stacks, but it is also necessary to control the interplay between the increase of the working voltage and the electrical conductivity of LiMnPO4 stacks.

We present the study on the structure and adsorption properties of reduced graphene oxide subjected to thermal treatment in temperature range of 1100–2000 °C under flowing argon. The morphology and composition analyses reveal that the defective carbon materials remaining after volatilization of oxygen and hydrogen rearrange into highly ordered hexagonal carbon layers during thermal treatment at 2000 °C. The surface area of the resulting carbon layers increases to a value more than fourfold over that of the starting precursor materials. These results offer useful insights to understand the thermal behavior of the carbonaceous decomposition materials.

•The near-surface dilution of trace Pd atoms is achieved to facilitate Pd-H bond cleavage.•A selective etching-deposition approach is developed to isolate trace Pd atoms in the near-surface region of Ag nanocrystals.•The electrocatalytic hydrogen evolution activity is improved about 14 times with excellent durability as compared with Pd catalysts.•The surface lattice structure is unambiguously resolved by synchrotron-radiation characterizations.•This work represents a novel strategy for high-performance and low-cost electrocatalyst design.Pd is a versatile catalyst in various hydrogen-related catalytic applications; however, it typically exhibits low activity in electrocatalytic hydrogen evolution reaction (HER) as too strong Pd-H bonding makes the electronic desorption of H adatoms (Had) hardly occur. We herein report a selective etching-deposition approach to implant trace Pd atoms in the near-surface region of Ag nanocrystals, forming a heteratomic-rich Pd-Ag structure on Ag surface. This near-surface dilution of Pd atoms can dramatically facilitate the electronic desorption of Had. As a result, this approach enhances the electrocatalytic HER activity of Pd catalysts about 14 times with excellent performance durability, approaching the high level of Pt catalysts. While enhancing the catalytic performance, this atomic implantation strategy allows the substantial reduction of material costs. This work thus represents a step toward the high-performance, low-cost catalyst design through near-surface lattice engineering.A selective etching-deposition approach has been developed to implant trace Pd atoms in the near-surface region of Ag nanocrystals. The formation of heteratomic-rich Pd-Ag structures can facilitate the electronic desorption of hydrogen adatoms to substantially enhance electrocatalytic hydrogen evolution reaction.

Designing Prussian blue with optimally exposed crystal planes and confining it in a conductive matrix are critical issues for improving its sodium storage performance, and will result in much improved sodium ion adsorption and diffusion, together with improved electron mobility. Here, we firstly illustrate through DFT simulations that the {100} lattice planes and [100] direction of the KxFeFe(CN)6 crystal are the preferred occupation sites and diffusion route for sodium ions. In addition, through coupling with RGO, KxFeFe(CN)6 electrodes exhibit better electronic conductivity. Accordingly, {100} plane-capped cubic K0.33FeFe(CN)6 wrapped in RGO was fabricated using a facile CTAB-assisted method. Due to the highly robust framework, higher specific surface area, greatly reduced number of lattice water defects and conductive RGO coating, K0.33FeFe(CN)6/RGO exhibits superior electrochemical performance in sodium-ion batteries. As a cathode, the RGO-coated K0.33FeFe(CN)6 yields an initial discharge–charge capacity of 160 mA h g−1 at a rate of 0.5C, and an excellent capacity retention of 92.2% at 0.5C and 90.1% at 10C after 1000 and 500 cycles. Furthermore, XRD, DFT simulation, XANES and EXAFS verified that the structural changes during the Na-ion insertion–extraction processes are highly reversible. All these results suggest that {100} plane-capped K0.33FeFe(CN)6/RGO has excellent potential as a cathode for sodium-ion batteries.

Two-dimensional layered structure of a single crystal is regarded as an ideal feature for physical and chemical fundamental studies. Herein, we demonstrated a high-quality (NH4)2V3O8 single crystal with a layered tetragonal structure prepared via a hydrothermal method. The lattice vibrational behavior and surface electronic state of (NH4)2V3O8 layers were systematically investigated via polarized Raman scattering spectroscopy and ultraviolet photoelectron spectroscopy (UPS), respectively. It was found that all Raman peaks of (NH4)2V3O8 could be clearly identified as four active Raman modes through parallel and perpendicular polarization configurations in the backscattering geometry for (001) crystal surface. The UPS results indicated that the valence band maximum of (NH4)2V3O8 was mainly composed of localized vanadium 3d states, which was further confirmed by the density functional theory calculations.

Thin, planar nanojunctions between layered 2H/1T-MoS2 and graphitic C3N4 (g-C3N4) were fabricated and 1T phase nanojunctions allowed faster photogenerated electrons across the junction interfaces to facilitate hydrogen evolution. This research represents a proof of concept for the rational fabrication of thin 1T phase interfacial junctions and the importance of the 1T phase for further improving the HER perfomance.

Carbon layer-coated molybdenum dioxide nanoparticles exhibit strong photo-absorption in the near infrared (NIR) region with good photostability. The in vitro and in vivo experiments reveal that an excellent photothermal ablation induced from the nanoparticle agents under NIR irradiation can kill tumor cells not only at the cellular level but also in living organs.

Layered Cu2MoS4, consisting of earth-abundant elements, is regarded as a potential catalyst for the hydrogen evolution reaction (HER). Herein, we demonstrate a Cu2O-based template strategy to synthesise hierarchical hollow nanostructures of Cu2MoS4. The characterizations reveal that the electrochemically active surface of the hollow Cu2MoS4 is largely enhanced, in contrast to the nanosheet or nanoparticle structures. As the direct outcome, the designed hierarchical hollow structures display excellent HER activities with a low overvoltage and small Tafel slope. This study may provide new inspiration for the research of other ternary sulphide materials as well as subsequently accelerating their applications in the field of catalysis.

A room-temperature ferromagnetic behavior was observed in a ternary layered-Cu2MoS4 nanosheet. Both the coercivity and magnetization saturation increased with a decrease in temperature. The electron paramagnetic resonance spectroscopy confirmed a high g value. Combined with atomic structural observations, our first principle calculations revealed that the ferromagnetism originated from the edged molybdenum atoms.