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CO2 electroreduction powered by renewable electricity represents a promising method to enclose anthropogenic carbon cycle. Current catalysts display high selectivity toward the desired product only over a narrow potential window due primarily to unoptimized intermediate binding. Here, we report a functional ligand modification strategy in which palladium nanoparticles are encapsulated inside metal–organic frameworks with 2,2′-bipyridine organic linkers to tune intermediate binding and thus to sustain a highly selective CO2-to-CO conversion over widened potential window. The catalyst exhibits CO faradaic efficiency in excess of 80% over a potential window from −0.3 to −1.2 V and reaches the maxima of 98.2% at −0.8 V. Mechanistic studies show that the 2,2′-bipyridine on Pd surface reduces the binding strength of both *H and *CO, a too strong binding of which leads to competing formate production and CO poison, respectively, and thus enhances the selectivity and stability of CO product.

Black phosphorus has been reported as a remarkable 2D material due to its unique electrical, optical, and thermal properties, leading to promising device applications in optics, thermoelectricity, ...

Recently, halide solid-state electrolytes (SSEs) have been reported to exhibit high ionic conductivity and good compatibility with cathode materials. However, the air stability of halide-based elec...

Black phosphorus (BP) has recently attracted intense research interest due to its unique thickness-dependent and anisotropic electronic and photonic properties, and has shown promising potential in nanophotonic, nanoelectronics and energy storage applications. However, the application of BP in practical devices is hindered by its high commercial cost. To further reduce the cost and accelerate the development of BP, a highly efficient preparation strategy for low-cost BP must be found. Herein, we report such a method via a modified chemical vapor transport (CVT) method by replacing high-purity red phosphorus (RP) with a low-purity precursor counterpart. We show that this method can drastically reduce the cost of manufacturing by several orders of magnitude. Furthermore, the BP produced using low-cost RP shows nearly the same crystal quality, high purity, local chemical structure, and electronic properties, compared with those of the high-cost BP prepared by the traditional CVT method. Most importantly, exfoliated phosphorene nanosheets prepared from the low-cost BP exhibit promising hydrogen evolution reaction (HER) activity. Owing to the high quality and high conversion efficiency, the low-cost BP holds promising potential in future scientific research and industrial applications.

All-solid-state lithium sulfur batteries (ASSLSBs) are considered promising candidates for next-generation energy-storage systems due to their enhanced safety and high theoretical energy density. However, usually both solid-state electrolyte (SSE) and conductive carbon need to be incorporated into the cathode composite to provide Li+/electron pathways, leading to the reduced energy density and inevitable SSE decomposition. Moreover, the real electrochemical behavior of S or Li2S cathodes can not be reflected due to the partially overlapped redox reaction of SSE. Herein, a series of unique P4S10+n cathodes for high-performance ASSLSBs that totally do not need any extra SSE additives are reported. Synchrotron-based X-ray absorption near edge structure coupled with other analyses confirmed that ionic conductive Li3PS4 together with Li4P2S6 components can be electrochemically self-generated during lithiation process and partially maintained to provide fast Li+ transport pathways within the cathode layer. This is further evidenced by a 30–43-fold higher reversible capacity for P4S10+n/C cathodes compared to a S/C cathode. Bulk-type ASSLSBs based on the P4S34/C cathode show a highly reversible capacity of 883 ​mAh g−1 and stable cycling performance over 180 cycles with a high active material content of 70 ​wt%. The present study provides a promising approach for generating ionic conductive components from the electrode itself to facilitate Li+ migration within electrodes in ASSLSBs.

Phosphorene, single- or few-layered black phosphorus, has been rediscovered as a promising two-dimensional material owing to its unique optical, thermal, and electrical properties with potential applications in optoelectronics, nanoelectronics, and energy storage. However, rapid degradation under ambient condition highly limits the practical applications of phosphorene. Solving the degradation problem demands an understanding of the oxidization process. We, for the first time, apply synchrotron-based X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge structure (XANES), and scanning transmission X-ray microscopy (STXM) for the nanoscale chemical imaging of phosphorene degradation. Through these methods, we have identified chemical details of the morphological effect and clarified thickness and proximity effects, which control the oxidization process. Furthermore, the entire oxidization process of phosphorene has also been studied by in situ XPS and XANES, showing the step-by-step oxidization process under the ambient condition. Theoretical calculations at the density functional theory level support experimental findings. This detailed study provides a better understanding of phosphorene degradation and is valuable for the development of phosphorene-based materials.

All-solid-state batteries are expected to be promising next-generation energy storage systems with increased energy density compared to the state-of-the-art Li-ion batteries. Nonetheless, the electrochemical performances of the all-solid-state batteries are currently limited by the high interfacial resistance between active electrode materials and solid-state electrolytes. In particular, elemental interdiffusion and the formation of interlayers with low ionic conductivity are known to restrict the battery performance. Herein, we apply a nondestructive variable-energy hard X-ray photoemission spectroscopy to detect the elemental chemical states at the interface between the cathode and the solid-state electrolyte, in comparison to the widely used angle-resolved (variable-angle) X-ray photoemission spectroscopy/X-ray absorption spectroscopy methods. The accuracy of variable-energy hard X-ray photoemission spectroscopy is also verified with a focused ion beam and high-resolution transmission electron microscopy. We also show the significant suppression of interdiffusion by building an artificial layer via atomic layer deposition at this interface.

CO

Lithium–sulfur batteries are regarded as the imminent energy storage device for high energy density applications. However, at practical sulfur loadings >5 mg cm−2, the cell suffers from severe capacity fade and durability. In the present work, a hybrid MoS2–WS2 heterodimensional structure is reported. The strain induced growth of transition metal dichalcogenides preferentially exposes edge sites and maximizes the geometric coverage for anchoring-diffusion-conversion of polysulfides to restrain the shuttle effect at practical S-loadings. The systematic analysis (5–50 mg cm−2 of S-loadings) reveals that the unique cathode architecture exhibits reversible S-loading tolerance up to 28 mg cm−2. A high initial areal capacity of 32 mAh cm−2 with an area specific energy density of 67 mWh cm−2 is achieved with a low electrolyte volume/S-loading ratio of 5 mL g−1. The strategy presented here can unlock high S-loading Li–S cells with extended cyclability and high energy density.

Designing efficient catalysts with high activity and selectivity is desirable and challenging for CO2 reduction reaction (CO2RR). Nickel phthalocyanine (NiPc) is a promising molecule catalyst for CO2RR. However, the pristine NiPc suffers from poor CO2 adsorption and activation due to its electron deficiency of Ni–N4 site, which leads to inferior activity and stability during CO2RR. Here, we develop a substituent-induced electronic localization strategy to improve CO2 adsorption and activation, and thus catalytic performance. Theoretic calculations and experimental results indicate that the electronic localization on the Ni site induced by electron-donating substituents (hydroxyl or amino) of NiPc greatly enhances the CO2 adsorption and activation, which is positively associated with the electron-donating abilities of substituents. Employing the optimal catalyst of amino-substituted NiPc to catalyze CO2 into CO in flow cell can achieve an ultrahigh activity and selectivity of 99.8% at the current densities up to 400 mA cm-2. This work offers a novel strategy to regulate the electronic structure of the active site by introducing substituents for highly efficient CO2RR.

Alkali-activated materials (AAMs), sometimes called geopolymers, are eco-friendly cementitious materials with reduced carbon emissions when compared to ordinary Portland cement. However, the availability of most precursors used for AAM production may decline in the future because of changes in industrial sectors. Thus, new precursors must be developed. Recently there has been increased interest in synthetic glass precursors. One major concern with using synthetic glasses is ensuring that they react sufficiently under alkaline conditions. Reactivity is a necessary, although not sufficient, requirement for a suitable precursor for AAMs. This work involves the synthesis, characterization, and estimation of alkaline reactivity of Na-Mg aluminosilicate glasses. Structural characterization showed that replacing Na with Mg led to more depolymerization. Alkaline reactivity studies indicated that, as Mg replaced Na, reactivity of glasses increased at first, reached an optimal value, and then declined. This trend in reactivity could not be explained by the conventional parameters used for estimating glass reactivity: the non-bridging oxygen fraction (which predicts similar reactivity for all glasses) and optical basicity (which predicts a decrease in reactivity with an increase in Mg replacement). The reactivity of the studied glasses was found to depend on two main factors: depolymerization (as indicated by structural characterization) and optical basicity. Depolymerization dominated initially, which led to an increase in reactivity, while the effect of optical basicity dominated later, leading to a decrease in reactivity. Hence, while designing reactive synthetic glasses for alkali activation, structural study of glasses should be given due consideration in addition to the conventional factors.

Due to the inevitable chemical reactions between the nucleophilic lithium polysulfides and electrophilic carbonate solvents, conventional S cathodes are incompatible in carbonate-based electrolytes...

Numerous efforts are made to improve the reversible capacity and long-term cycling stability of Li-S cathodes. However, they are susceptible to irreversible capacity loss during cycling owing to shuttling effects and poor Li

The effect of phosphorus addition on silica-supported cobalt catalyst was investigated for Fischer-Tropsch synthesis (FTS). As shown by STEM images and chemisorption, the addition of phosphorus to cobalt of up to 1 wt% increased the dispersion of cobalt. Further addition of phosphorus (e.g., 3 and 5 wt.%), as demonstrated by TPR, pulse reoxidation, and XANES, significantly hindered the reduction of cobalt oxides. The cobalt FTS catalysts containing 0.5 and 1.0 wt% P exhibited greater stability in comparison with undoped and 3.0 wt% P containing cobalt catalysts. Analysis of XANES spectra at the P and Co K-edges, along with DRIFTS results of H 2 -activated cobalt catalysts, suggest that cobalt particles interact with PO 4 3− ions, indicating a role played by P in anchoring Co particles to the support, thus hindering the cobalt sintering rate. The initial selectivity to methane was slightly higher for 0.5%P-20%Co/SiO 2 and 1.0%P-20%Co/SiO 2 catalysts compared to the undoped catalyst, but at longer times differences were small. At higher loadings of P (3 wt.%), FT activity and selectivity were adversely and irreversibly affected.

The effect of co-fed hydrogen chloride (HCl) in syngas on the performance of iron and cobalt-based Fischer–Tropsch (FT) catalysts was investigated in our earlier studies (Ma et al. in ACS Catal 5:3124–3136, 2015; Davis et al., DOE final report, 2011; Gnanamani et al. in Catal Lett 144:1127–1133, 2014). For an iron catalyst, lower HCl concentrations (

The effect of 1.0 ppm H2S in the syngas feed on initial activity and selectivity of a 0.5%Pt–25%Co/Al2O3 catalyst was studied by comparing the catalyst performance under H2S and sulfur free conditions. The reaction tests were performed using a 1-L slurry phase reactor for 141–212 h under constant reaction conditions: 220 °C, 2.0 MPa, H2/CO = 2.0 and 6.0 Nl/g-cat/h. In the H2S poisoning test, an H2S in N2 gas mixture was added to the syngas feed (1.0 ppm) after running the Fischer–Tropsch synthesis (FTS) reaction for ca. 6.0 h; as such, the impact of H2S on the initial deactivation of the cobalt catalyst (unsteady state) was successfully assessed. The used catalysts were characterized by XANES to investigate if Co–S surface species were formed during the deactivation. The initial deactivation under 1.0 ppm H2S condition was significantly higher (by 2.0–2.4 times) than that under clean conditions. CH4 selectivity increased substantially and C5+ selectivity decreased greatly with time regardless of whether H2S was added or not; however, the addition of H2S accelerated the changes in the hydrocarbon selectivities, which were likely caused by the sharp deactivation of the catalyst in the presence of H2S. After co-feeding the sulfur for 141 h, a comparison was made at similar conversions by adjusting space velocity; the sulfur pretreated cobalt catalysts favored heavier hydrocarbons (C5+) formation and suppressed lower hydrocarbon formation. The addition of H2S to the feed increased CO2 selectivity and the secondary reaction of 1-olefins. The XANES results revealed that surface species involving Co–S bonding formed on the cobalt catalyst after exposure to H2S during FTS. This was likely the primary reason for the abnormal selectivity trends observed during and after the deactivation of the catalyst by sulfur. This study points out a possible approach to increase the selectivity to heavy hydrocarbons by properly sulfiding the cobalt catalyst prior to the FTS reaction.

Sequential impregnation and calcination were used to fill the pores of a commercial alumina support with alumina. In this manner, two different pore-modified alumina supports were synthesized. To account for the diminished pore size, cobalt loadings were lowered as appropriate to ensure a similar cobalt size range (e.g., clusters 14–18 nm in diameter) and comparable extents of reduction. This was confirmed by measurements from TPR, hydrogen chemisorption/pulse reoxidation, and EXAFS/XANES spectroscopies. Catalysts were tested using a slurry phase CSTR reactor at commercially relevant FTS conditions. Selectivities were compared at both high and low levels of conversion for the catalyst series. Decreasing the pore length, as measured by PSD data, appears to lessen the adverse effect that the higher relative diffusional rate of hydrogen versus carbon monoxide has on the H2/CO surface fugacity ratio on the catalyst surface. That is, moving the cobalt particles closer to the pore mouth may prevent the H2/CO ratio from being augmented at the surface of cobalt particles due to diffusion or other factors, and inhibits excessive chain termination that would lead to higher light product selectivities. Pore filling thus results in a catalyst that is similar to an egg-shell catalyst. With increased pore filling by alumina, C1 C4 light gas selectivities decreased, in a systematic way, by as much as 33% (relative basis), and the C5+ selectivity improved by as much as 10.3% (relative basis) in comparison with the 22.4%Co/Al2O3 (IWI) reference catalyst. This greater effectiveness offers an opportunity for more environmentally benign chemical processing.

X-ray emission spectroscopy (XES), as a complementary technique to x-ray absorption spectroscopy (XAS), is powerful in the analysis of the electronic structure of the materials by probing the occupied density of states with high energy resolution. Recently, an XES spectrometer optimized for the tender x-ray region (2–5 keV) was successfully installed into an inert atmosphere glovebox, and the entire system was successfully integrated into the SXRMB (soft x-ray microcharacterization beamline) at the Canadian Light Source. Here, the technical design and the performance of the SXRMB XES-integrated glovebox station is presented. High energy resolution of ∼1 eV or better has been achieved for the spectrometer in the tender energy x-ray ranges. Capability of the station for in-situ XES and XAS measurements is demonstrated using an example of phosphorus phase transformation in phosphorus anodes for lithium-ion battery research.

The sulfur limit, the relationship between the sulfur added and the surface Fe atoms lost (Fe/S), and mechanism of sulfur poisoning were studied using an iron Fischer–Tropsch synthesis (FTS) catalyst (100 Fe/5.1 Si/2.0Cu/3.0K). The FTS reaction was carried out at 230–270 °C, 1.3 MPa, H2/CO = 0.67–0.77 and 30–70% CO conversion using a 1-L slurry phase reactor. The used Fe catalysts were characterized by XRD, Mossbauer spectroscopy and XANES spectroscopy to understand the deactivation mechanism of the Fe based catalyst after adding up to 1 ppm H2S in the feed. Co-feeding of 0.1 ppm H2S in syngas for 70 h caused a very small change in the activity of the Fe catalyst, but increasing the H2S level to 0.2 ppm or above resulted in measurable deactivation of the Fe catalyst over a similar time period. The limit of sulfur level in the syngas feed (sensitivity) was determined to be 50 ppb. The added sulfur improved the selectivities of the secondary reactions of olefins and the WGS reaction even though the rates for these declined. The addition of H2S decreased CH4 selectivity and increased C5+ selectivities of the Fe catalyst. The Fe/S ratio, which can be used to define the poisoning ability of sulfur for the iron catalyst, was quantified based on the deactivation data obtained. The Fe/S ratio strongly depended on temperature and decreased remarkably with increasing temperature. At 270 °C one sulfur atom was found to eliminate ∼6 surface Fe atoms, and the ratio increased to 7.2 at 260 °C and increased further to 13.5 at 230 °C. The Fe/S relationship with increasing temperature is in good agreement with sulfur sorption theory. The changes in FTS and WGS rates of the Fe catalyst by sulfur were also studied. The decreases in rates of the two reactions were nearly the same. The results of XRD and Mossbauer spectroscopy indicated that the online addition of sulfur did not greatly alter the distributions of iron carbide and magnetite. Both data sets consistently suggest an adsorption mechanism, in line with the results of reaction testing. XANES results at the S K-edge further confirmed sulfur adsorption, and some sulfide and sulfate species, likely confined to the surface zone, were detected. In this study, the sulfur tolerances of the precipitated Fe and a supported Co catalyst were compared at an identical temperature (i.e., 230 °C), and similar M/S ratios (13.5–15.0) were obtained.

The effect of Cu, Mn and Zn addition on cobalt ferrite was investigated for Fischer–Tropsch synthesis (FTS). Oxalate co-precipitation followed by decomposition under inert conditions was used to obtain various metal containing cobalt ferrites (Co0.7M0.3Fe2O4). The carburization of cobalt ferrite in flowing CO at 270 °C and 175 psig yielded iron carbides (χ-Fe5C2 and e′-Fe2.2C) along with a bimetallic FeCo alloy. The extent of carburization was compared among Cu, Mn, and Zn doped catalysts with undoped cobalt ferrites under similar conditions. XRD and Mossbauer spectroscopy analysis of the freshly carburized samples followed by passivation revealed that carburization of cobalt ferrite did not change appreciably with addition of Cu or Mn. On the other hand, Zn was found to retard the carburization of cobalt ferrite. Analysis of the used FT catalysts suggests that Cu is less efficient over Mn and Zn in stabilizing the iron carbides (i.e., active form of iron) during FT synthesis. The FT activity remains more or less the same for the undoped, Cu and Zn containing cobalt ferrites at higher temperatures. The CO conversion of Co0.7Mn0.3Fe2.0 catalyst was much lower than the other catalysts tested. Addition of Zn or Mn to cobalt ferrite was found to promote alcohol formation, particularly at higher reaction temperatures. The water–gas shift activity of the catalysts was found to decrease in the following order, Co1.0Fe2.0 > Co0.7Mn0.3Fe2.0 > Co0.7Zn0.3Fe2.0 > Co0.7Cu0.3Fe2.0.

Olivine-type phosphates (LiMPO 4 , M = Fe, Mn, Co) are promising cathode materials for lithium-ion batteries that are generally accepted to follow first order equilibrium phase transformations. Herein, the phase transformation dynamics of sub-micro sized LiFePO 4 particles with limited rate capability at a low current density of 0.14 C was investigated. An in-situ X-ray Absorption Near Edge Structure (XANES) measurement was conducted at the Fe and P K-edge for the dynamic studies upon lithiation and delithiation. Fe K-edge XANES spectra demonstrate that not only lithium-rich intermediate phase Li x FePO 4 (x = 0.6–0.75), but also lithium-poor intermediate phase Li y FePO 4 (y = 0.1–0.25) exist during the charge and discharge, respectively. Furthermore, during charge and discharge, a fluctuation of the FePO 4 and LiFePO 4 fractions obtained by liner combination fitting around the imaginary phase fractions followed Faraday's law and the equilibrium first-order two-phase transformation versus reaction time is present, respectively. The charging and discharging process has a reversible phase transformation dynamics with symmetric structural evolution routes. P K-edge XANES spectra reveal an enrichment of PF 6 −1 anions at the surface of the electrode during charging.

Photoemission spectroscopy (PES) has been used widely to study the electronic structure of valence and core levels. However, conventional PES is surface-sensitive. To probe the interface and bulk properties of materials, hard X-ray photoemission spectroscopy (HXPES) has received increasing interest in the last decade, because of the deep probing ability of photoelectrons with higher kinetic energies (2–10 keV). Recently, a HXPES system was developed at the Canadian Light Source, using the high-energy version of a R4000 electron analyzer-based spectrometer connected to a medium-energy beamline, the soft X-ray microcharacterization beamline (SXRMB). Excellent performance of the beamline and the spectrometer is demonstrated herein using Au Fermi and 4f core lines; and the controlled probing depth of HXPES at SXRMB is demonstrated by tuning the photon energy (2–9 keV) in the study of a series of SiO2/SiC multilayer samples. Combined with the high-resolution X-ray absorption spectroscopy available at the SXRMB, the HXPES offers a powerful nondestructive technique for studying bulk properties of various materials.

Three mortar samples from the Abbey of Saint John, in the Swiss village of Mustair have been investigated. Two samples were taken from Carolingian plaster and the third one from a late Gothic plaster. All three samples were embedded in a synthetic resin (Araldite 2020) to be prepared as thin sections. The samples were pre-characterized using polarized light microscopy and some standard wet chemical procedures for determining in an indirect way the various chemical compounds in the samples. These experiments indicated differences between the samples in the composition of the binder materials (hydraulic and dolomitic components for the Carolingian samples, pure dolomitic lime for the Gothic sample) as well as in the composition of the aggregates that came, however, in all cases from local river sand. Using synchrotron radiation (SR) from the Canadian Light Source the three samples were investigated using spatially resolved (∼300 × 300 μm2 resolution) SR excited X-ray fluorescence (XRF) with an excitation energy of 9 keV. For some selected elements (Ca and Fe) X-ray absorption near edge structure (XANES) spectroscopy was used as well. Ca and Fe have the highest fluorescence intensity for all investigated points (at least 26 per sample) for all three samples and thus they are besides Si the most abundant elements. There are correlations between the XRF intensities of Mg, Sr and Ca and Fe and Si indicating chemical bonds between these elements. As there is no positive correlation between the intensities of Al, Si and Ca significant contributions of calcium-silicates and calcium-aluminates as sources for hydraulic setting can be ruled out. The analysis of the Ca-K-edge XANES spectra showed that calcite is the dominant form for Ca in the samples; however for “white spots” Ca is also available in the form of vaterite and for “dark spots” in the form of hydroxyapatite. Also Fe is observed in different forms in the white and dark spots: for both types of spots valence +3 as in Fe2O3 is the dominant form; however, in white spots fits are significantly improved by adding contributions from Fe3O4 and for the dark spots by adding FeO. The above summarized observations are correct for the Carolingian samples as well as for the Gothic sample. No significant age dependent differences were observed.

A series of transition metal incorporated MCM-41 mesoporous silica is successfully synthesized by hydrothermal method, and all of them display optical absorption in ultraviolet-visible light region. Analysis results from different characterization techniques demonstrate that the transition metal ions are well dispersed in the silica framework and mainly in tetrahedral coordination. In comparison to Co and Ni incorporated MCM-41, Fe-MCM-41 shows considerable photocatalytic activity for hydrogen production, without loading any noble metal as cocatalyst. The activation for photocatalytic reaction is induced by the ligand-to-metal charge-transfer (LMCT) excitation of the monometallic centers in the framework-substituted MCM-41. Bimetal co-incorporation is found to be effective for the enhanced photocatalytic activity. For instance, Fe/Ni co-incorporated MCM-41 shows much higher photocatalytic activity for hydrogen production than either Fe or Ni incorporated MCM-41 indicating synergistic effect of co-doping with Fe and Ni. The main reason for the enhanced activity is attributed to the metal-to-metal charge–transfer (MMCT) excitation creating oxo-bridged bimetallic redox sites, which results in efficient charge separation and creation of long-lived electrons and holes to initiate redox reaction.

A series of Li3V2−2/3xZnx(PO4)3/C phases were synthesized by carbon thermal reduction assisted by the ball-mill process. Scanning electron microscopy (SEM) showed that the irregular morphology of the pristine Li3V2(PO4)3/C could be transformed to spherical upon doping with a suitable amount of zinc. The structural stability of the pristine and the Zn doped Li3V2(PO4)3/C were investigated via X-ray absorption near edge structure (XANES) spectroscopy and X-ray diffraction (XRD). The results revealed that Zn doping not only improves the stability of the VO6 octahedral structures before electrochemical cycling, but also reduces the degree of irreversible expansion of the c axis and the crystal volume upon repeated cycles. Among the Li3V2−2/3xZnx(PO4)3/C (0 ≤ x ≤ 0.15) series, the sample doped with 0.05 Zn atoms per formula unit showed the best electrochemical performance. Excess Zn doping (x > 0.05) didn't result in further improvement in the electrochemical performance due to the segregation effect and the inactive nature of Zn.

We present a theoretical interpretation of the L3,2-edge XANES (X-ray Absorption Near Edge Structure) spectra of un-doped and zinc-doped As2Se3 glasses. L3,2-edge XANES of glasses with compositions, (As2Se3)100 − x(Zn)x (x = 3, 5, 7, 10) and (As2Se3)100 − y (ZnSe)y (y = 5, 20), have also been obtained experimentally. The experimental L3,2-edge spectra of As and Se are compared to the theoretically calculated spectra by two ab-initio methods: the self-consistent methods of DFT (Density Functional Theory) and RSMS (Real Space Multiple Scattering). The effect of morphology (powder vs. thin film) and the addition of Zn are also demonstrated by valence band obtained from XPS (X-ray Photoelectron Spectroscopy) spectra. The effects of the cluster size and the doping of Zn into the As2Se3 have also been simulated for the L3,2-edge XANES.

A series of Li3V(2-2/3x)Zn(x)(PO4)3/C phases were synthesized by carbon thermal reduction assisted by the ball-mill process. Scanning electron microscopy (SEM) showed that the irregular morphology of the pristine Li3V2(PO4)3/C could be transformed to spherical upon doping with a suitable amount of zinc. The structural stability of the pristine and the Zn doped Li3V2(PO4)3/C were investigated via X-ray absorption near edge structure (XANES) spectroscopy and X-ray diffraction (XRD). The results revealed that Zn doping not only improves the stability of the VO6 octahedral structures before electrochemical cycling, but also reduces the degree of irreversible expansion of the c axis and the crystal volume upon repeated cycles. Among the Li3V(2-2/3x)Zn(x)(PO4)3/C (0 ≤x≤ 0.15) series, the sample doped with 0.05 Zn atoms per formula unit showed the best electrochemical performance. Excess Zn doping (x0.05) didn't result in further improvement in the electrochemical performance due to the segregation effect and the inactive nature of Zn.

Silicon 1s Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of silicon nanocrystals have been examined as a function of nanocrystal size (3-100 nm), varying surface functionalization (hydrogen or 1-pentyl termination), or embedded in oxide. The NEXAFS spectra are characterized as a function of nanocrystal size and surface functionalization. Clear spectroscopic evidence for long range order is observed silicon nanocrystals that are 5-8 nm in diameter or larger. Energy shifts in the silicon 1s NEXAFS spectra of covalently functionalized silicon nanocrystals with changing size are attributed to surface chemical shifts and not to quantum confinement effects.