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In this work, we report the growth process of pristine and cobalt (2%, 4%, 6% and 8%) doped TiO2 thin films on LaAlO3(100) substrate by molecular beam epitaxy (MBE) technique. The microstructural, magnetic, optical, photoconductivity and photocatalytic activity of the films were explored. Reflection high-energy electron diffraction (RHEED) confirms successful growth of single phase anatase TiO2 thin film and effects of cobalt (Co) doping on crystal phase depending on the growth conditions and correlating changes in their physical properties. X-ray diffraction and X-ray photoelectron spectroscopy (XPS) establish highly pure crystalline nature and oxidation state of the elements. Magnetic measurements show room temperature ferromagnetism in all the thin films and suggest that growth conditions, oxygen vacancies and bound magnetic polaron (BMP) model account for the magnetic properties. The optical properties exhibit a red shift response associated with narrowing bandgap that influence photocatalytic activity. The 8% cobalt doped TiO2 film has shown 91% degradation with methylene blue and 88% degradation with Azo dye in 70 min under visible light irradiation exhibiting excellent photocatalytic performance. The photoconductivity measurements have confirmed photosensitive nature of TiO2 and 8% Co doped TiO2. Therefore, these opto-magnetic properties can be tuned for the applicability of future spintronic and optical devices.

CeO2 with four different morphologies (sphere, rod, octahedron, cube) are used as the supports to synthesize the CuCe catalysts for the CO preferential oxidation in the H2-rich gas and characterized by various techniques (TEM, HR-TEM, SEM, XRD, N2 physisorption, XPS, Raman spectra, CO-TPD, CO-DRIFTS, O2-TPD, CO pulses, H2-TPR) to obtain an insight into the impact of the CeO2 morphology on the surface structure, composition and redox properties, especially the active species. The four supports expose {111}, {110} and {100} planes, and sphere-shape CeO2 has a higher ratio of {111}, which can form more reductive copper species and active oxygen species. And the catalytic performance followed by this order: spheres (28.5 kJ/mol) > rods (31.0 kJ/mol) > octahedrons (34.1 kJ/mol) > cubes (40.3 kJ/mol). By further analysis of the characterization results, a series of structure-activity relationships are established to confirm that the active oxygen species is the decisive factor of preferential oxidation of CO in the H2-rich stream.

The effect of P addition on the catalytic performance of La/HZSM-5 in methyl mercaptan abatement was investigated in the present work. It was shown that the addition of phosphorus could decrease the amounts of strong acid sites over the P-doped 13%La/HZSM-5 samples, but expected coke resistance ability was not obtained. To our surprise, P-doped 13%La/HZSM-5 samples exhibited decreased activity and stability for methyl mercaptan abatement. Moreover, the 13%La/HZSM-5 supported P catalysts were prepared and characterized by NH3-TPD, FT-IR, XRD and XPS, and it was found that the introduction of P species into La/HZSM-5 catalyst provokes a reaction with La2O3 and La2Ox(CO3)y species, which were reported to be active sites for methyl mercaptan conversion. As a result, P addition generated some inactive species such as AlPO4, Al(PO3)3, LaPO4 and La(PO3)3 species, causing the deactivation of the catalyst. These results conversely proved the necessary presence of active La2O3 and La2Ox(CO3)y species in the La/HZSM-5 catalyst for eliminating CH3SH.

Adsorption behavior of thiadiazole derivatives, 2,5-bis(ethyldisulfanyl)-1,3,4-thiadiazole (DTA), dimercapto-1,3,4-thiadiazole (DMDT) as anticorrosion additives at copper oxide surface were studied by first-principles calculations, weight loss, electrochemical and surface characterization techniques. The adsorption energies calculated by density functional theory (DFT) were less than 0.3 eV, DTA and DMDT physically adsorbed on the copper surface and cannot replace the oxygen atom at the top site of the Cu O slab models. The predicted physically interaction of the corrosion inhibitor on the copper surface, which was basically consistent with the results of XPS analysis and surface microtopography. It was shown that in the presence of DTA and DMDT adsorbed on copper surface depress the reaction rate of anodic dissolution and cathodic hydrogen evolution and obey Langmuir isotherm. Surface findings indicated the inhibitor film formed at copper surface can block corrosion and improve hydrophobicity.

The long-lasting chrome-free, corrosion-resistant surface treatment of aluminum is of crucial importance. In our work, we prepared an intrinsic self-repairing and self-antibacterial film of single step in-situ grown inorganic lithium (Li), aluminum (Al)-containing layered double hydroxides film modified by 2-guanidinosuccinic acid (denoted as GLDHs) on the surface of 6 N01-T5 Al alloy by a facile method with enhanced corrosion protection performance. A series of electrochemical tests and neutral salt tests (NSS) showed that the corrosion resistance performance of GLDHs was significantly improved as compared with blank LiAl-LDH film. Interestingly, an artificial defect in the GLDHs film exhibited remarkable performances of self-repairing. After immersion in 3.5 wt% NaCl solution for certain time, new LiAl-LDH film at the Al alloy surface were formed, which was characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma emission spectrometer (ICP), elemental analyzer, polarization curves, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). A self-repairing mechanism was proposed and discussed. Furthermore, GLDHs also exhibited excellent self-antibacterial activity toward Escherichia coli and Bacillus subtilis. The high self-antibacterial performance of GLDHs film could attribute to the modified 2-guanidinosuccinic acid. Our full demonstration of the multifunctional GLDHs film is considerably beneficial to the researchers to further understand its potential for the practical application in the field of corrosion protection of aluminum and aluminum alloy.

By utilizing the convenient physical vapor deposition procedure, a simple and low-cost synthesis route is developed to fabricate high-quality orthorhombic MoO3 crystals with single crystallinity and significant size (bigger than 10 mm × 10 mm2). A combined characterization techniques of atomic force microscopy, X-ray photoelectron spectroscopy, synchrotron-based X-ray diffraction and Raman spectroscopy confirm the high quality of α-MoO3 crystal from the point view of both electronic and physical structures. Compared to previous reports in literature, we demonstrate herein a rather simplified one-step approach with only the MoO3 powder needed. In the end, corresponding electrochromic performance has also been tested which reveals high transmittance and remarkable optical properties which may broadens the potential applications of MoO3 single crystal in nanosensors, nanoelectronics and so on.

In this paper, we have investigated the effects of yttrium (Y) doping on the electrical performance and stability of ZnO thin film transistors (TFTs). Here, Y-doped ZnO TFTs were fabricated by using radio frequency magnetron sputtering at 150 °C. As a result, the 1% Y-doped ZnO TFT exhibits a small threshold voltage shifts of 2.5 V under positive bias stress and −2.8 V under negative bias stress as well as desirable device performance with field effect mobility of 9.8 cm2/V s, a subthreshold swing of 320 mV/decade and on/off current ratio of 107, respectively. Based on the XPS analysis and electrical characterizations, the improvement in stability and electrical properties of ZnO TFTs were attributed to the appropriate Y doping concentration, which not only could control the carrier concentration and broaden the band gap of ZnO film, but also suppress the oxygen vacancy defects and passivate the trap density at the SiO2/ZnO interfaces. Consequently, the high stability and excellent electrical performances of Y-doped ZnO TFTs show great potential for use in flat panel displays.

It is therefore difficult to develop anionic imprinted polymers due to its intrinsic properties of anionic templates, which have much smaller charge size ratio, species diversity, and irregular geometry than cationic templates. Moreover, its synthesis is not suitable for traditional apolar media. Hence, well-defined recognition cavities formed by coordination are almost impossible for anion imprinted polymers. Synthesized anion imprinted polymers (IIP) by electrostatic attraction of positive and negative charges to enhance the stability of anion and functional monomer in the pre-polymerization process were proposed. Speciation of phosphate and surface potential at different pH on IIP have effect on phosphate capture were investigated. The resultant IIP has a high 78.88 mg g−1 at 35 °C while non-anion imprinted polymers (NIP) has only 33.35 mg g−1 adsorption capacity. In coexist experiments, all the selectivity coefficients (α) of IIP are greater than 1.8, and selectivity would rise with anion concentration increased. All these shows IIP possessed outstanding selectivity and specificity to phosphate. Adsorption energy E, and ΔH0 of IIP are 14.26 kJ mol−1 and 36.32 kJ mol−1, respectively. It indicated that phosphate adsorbed to IIP is ion exchange reaction. It is further verified by FTIR and XPS that recognition sites of anion imprinted polymers are N+ of AMD and P–O− in H2PO4−. They moved to imprinted cavities and form N+–O−, N H hydrogen bonded, which also contribute to adsorption.

Disodium vanillin l -aspartic acid modified LiAl-layered double hydroxide (LDH) coating was fabricated on A6N01-T5 Al alloy by the one step in-situ synthesis at relatively low temperature. The characteristics of the modified LiAl-LDH (VLDH) coating were characterized by X-ray diffractometer (XRD), Flourier transformation infrared spectrometer (FT-IR), Scanning electron microscopy (SEM), Energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and Atomic force microscopy (AFM). The results showed that vanillin l -aspartic acid anions were successfully intercalated into the interlayer of LiAl-LDH to form the smoother and more compact surface of the VLDH coating. The corrosion resistance of the VLDH coating was investigated by Scanning electron microscopy (SEM), Energy dispersive spectrometer (EDS), Elemental analyzer (EA), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. These results indicated that the VLDH coating possessed the excellent ion-exchange property and the better corrosion resistance than the unmodified LiAl-LDH (NLDH) coating in 3.5 wt% NaCl solution. The corrosion resistance mechanism of the VLDH coating was proposed in this paper.

A commercial PVDF Microfiltration (MF) membrane was surface modified via a simple coating method for improvement of the hydrophilicity and anti-fouling performance. Herein, trace amounts of tannin acid (TA) and Polyethyleneimine (PEI) were firstly used with (3-Chloropropyl)trimethoxysilan (CTS) to endow the PVDF membranes with hydrophilicity. The physicochemical property of the modified membranes was characterized by SEM, AFM, ATR-FTIR and XPS respectively, and a series of tests including water contact angle (WCA), underwater oil contact angle (OCA), pure water flux (PWF), anti-fouling experiments and so on were utilized to inspect the modified effect. Benefiting from the interactions among CTS, PEI and TA, several coating layers formed on the surface of the membranes and remarkable hydrophilicity with water contact angle of 16° was obtained, moreover, the pure water flux of this composite membranes could reach 10,782 L/m2·h.

AlN thin films grown on different face sapphire substrates by metalorganic chemical vapor deposition were studied comprehensively by a variety of techniques including high resolution X-ray diffraction (HR-XRD), X-ray photoelectron spectroscopy (XPS), Raman scattering (RS) and theoretical calculations. Our results showed that substrate orientation has a drastic effect on the initial growth of AlN. The AlN films showed dominant semipolar (101) orientation but with slightly weaker individual features. Optical reflectance measurements confirmed that AlN films grown on different surface orientation sapphire substrates at the same time possessed different film thicknesses. It was found that the surface orientation also has a major influence on the dislocation density, crystallite size, and surface oxygen incorporation. Raman line width exhibited good correlation with XPS measurements. The combined analyses led to a better understanding of the variation in the quality of the AlN films grown on different faces of sapphires.

Surface topography had been identified as a crucial property that affects osseointegration; thus, topographical modification was the most frequently adopted technique in titanium-based implant research. In this study, ethyl cellulose was employed as an additive to construct a zinc-incorporated nano-network layer onto a titanium surface by the sequential treatments of spin-coating, high-temperature calcination, and alkali heat corrosion. SEM results showed that 20 mg/mL of ethyl cellulose was optimal to fabricate a relatively flat porous coating, and the ideal nano-network structures formed by only 4 h of corrosion. Other results of XPS and ICP further proved that zinc ions were successfully incorporated into the final samples (Ti-Zn0.1, Ti-Zn0.3, and Ti-Zn0.4). Moreover, the in vitro cellular (e.g., CCK-8, ALP, mineralization) and bacterial assays presented that Ti-Zn0.3 substrates not only had the greatest proliferation and differentiation capacities for osteoblasts but also possessed relatively strong antibacterial abilities for both Escherichia coli and Staphylococcus aureus. This study provided a new way to rapidly construct the pro-osteogenesis and antibacterial nano-network structures on titanium surfaces for orthopedic application.

In this paper, the carboxyl group functionalized mesoporous silica SBA-15 (SBA-15C), was firstly prepared by one-step co-condensation, then the HKUST-1 functionalized composite material (HKUST-1@SBA-15C) was synthesized in situ through the copper ions adsorbed by the carboxyl group ( COOH). The physicochemical properties of the composite material were characterized by FT-IR, TG, BET, XRD, XPS, SEM, and TEM. The results indicated that HKUST-1 had been successfully embedded into the pores of SBA-15C through the COOH groups on its surface. The stability and catalytic activity of the composite material were studied in the reduction reaction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. The catalytic performance of the composite material was not significantly reduced after 4 times reuse.

We report on the structure and reactivity of the Co-Si polycrystalline surfaces that form at room temperature (RT). Scanning tunneling microscopy (STM) was used to examine the surface morphology while X-ray photoelectron spectroscopy (XPS) was used to detect the chemical states of cobalt and silicon as a function of cobalt coverage. Moreover, XPS measurements after exposing the Co-Si(1 1 1) samples to CO gas provide information about CO adsorption and dissociation. When 5 ML, an indication that Co-rich silicides and metallic Co present. The CO adsorption capacity increases with cobalt dose up to 30 ML after which it levels off, an indication that metallic cobalt sites are dominantly exposed on the surface. Furthermore, a closed metal film is formed for 200 ML dose. Some dissociation of CO was observed during heating of the CO-covered samples for Co doses ≥30 ML.

In this study, the mechanical properties of SiCf/SiC composites with a BN/SiC multilayer interface was evaluated after oxidized at 800 °C, 1100 °C and 1400 °C for 200 h. The damage evolution of the fabricated and oxidized composites were analyzed by acoustic emission techniques. The chemical composition and structural evolution of the SiCf/SiC composites after oxidation were observed by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and energy dispersive spectroscopy. Significant temperature-dependent strength degradation of the SiCf/SiC composites was observed. The results indicated that the interfacial microstructure change caused by oxidation had a significant impact on the damage process of the composites, and two different degradation mechanisms for oxidized composites are discussed. The toughening mechanism of crack deflection and fiber pull out failed after oxidation at 800 °C. The degradation of the mechanical properties after oxidation at 1100 and 1400 °C was attributed to the hysteresis of fiber breakage caused by weak interface bonding. This work could predict the service life of SiCf/SiC composites and contribute to their early application in aerospace.

The solid reaction of lithium hydride and lithium hydroxide in lithium hydride pellet is first directly observed at normal ambient condition after 4 years storage. Layer-by-layer XPS results show that LiOH hydrolysis layer quickly forms on the LiH surface, LiOH reacts with bulk LiH to form Li2O and H2. Due to the great H2 outgassing after long time conservation, bubbling problem actually exists during the practical long-time preserving period. Using CO2 as pre-treatment gas during the LiH sample preparation process is a feasible way to prevent LiH sample from bubbling after long storage period. Moreover, Li2CO3 shows possible delay effect on the solid reaction of LiOH with LiH in this work, thus preserving LiH sample in CO2 containing atmosphere might also be an prospective way to protect the sample from further corrosion.

We report herein a means of transforming TiO2 nanotube arrays (TNAs) from an amorphous state to an anatase crystal state (denoted as ∗TNAs), and present a single-step synthetic route for preparing CdS quantum dots (CdS QDs) as well as reduced graphene oxide (rGO) through gamma-ray irradiation. The as-prepared ∗TNAs, CdS QDs, and rGO, which had all been subjected to gamma-ray irradiation, were then assembled together to produce the desired heterojunction (denoted as CdS QDs/rGO-∗TNAs). X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), ultraviolet/visible diffuse-reflectance spectroscopy (UV/Vis DRS), Fourier-transform infrared spectroscopy (FTIR), micro-Raman spectrometry (RS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) have been applied to characterize the appearance and performance of this photocatalyst. The photocatalytic activity of CdS QDs/rGO-∗TNAs towards ethylene degradation has been measured by placing it in a simulated cold-storage environment, the temperature and humidity of which were set at about 3 ± 1 °C and 75–90%, respectively. The results showed that the rate constant (K) of ethylene degradation could reach up to 1.07 × 10−3 min−1 with CdS QDs/rGO-∗TNAs, as compared to 2.30 × 10−4 min−1 with ∗TNAs and 6.25 × 10−4 min−1 with CdS QDs-∗TNAs, indicating that the constructed CdS QDs/rGO-∗TNAs constitutes a promising photocatalyst for ethylene removal in a cold storage environment.

Oxide formation on surface of nitrogen-rich uranium nitride film/particles was investigated using X-ray photoelectron spectroscopy (XPS), auger electron spectroscopy (AES), aberration-corrected transmission electron microscopy (TEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with electron energy-loss spectroscopy (EELS). XPS and AES studies indicated that the oxidized layer on UN2-x film is ternary compound uranium oxynitride (UNxOy) in 5–10 nm thickness. TEM/HAADF-STEM and EELS studies revealed the UNxOy crystallizes in the FCC CaF2-type structure with the lattice parameter close to the CaF2-type UN2-x matrix. The work can provide further information to the oxidation mechanism of uranium nitride.

An oxidized mesoporous carbon (OMC) with fluffy structure was fabricated from the mixture of petroleum asphalt and aluminum isopropoxide, and its structures were characterized by FESEM, TEM, BET, TG, XPS and FT-IR. In addition, bath absorption experiments for malachite green (MG) and lead ion (Pb2+) were carried out to explore the effects of pH, initial concentration, contact time and temperature on its absorption process. Results show that the OMC prepared has a fluffy ultrathin-wall structure with narrow pore size distribution and rich oxygen-containing groups. It exhibits excellent absorption performance for the removal of MG as well as Pb2+, as indicated by that its maximum adsorption capacity is 963.1 mg g−1 for MG and 198.6 mg g−1 for Pb2+. The absorption experimental data are all fitted well with pseudo-second-order model and Frendlich isotherm, respectively. More importantly, the OMC still maintains relatively high adsorption capacity after five cycles.

Quantitative analysis of Ni2+/Ni3+ using X-ray photoelectron spectroscopy (XPS) is important for evaluating the crystal structure and electrochemical performance of Lithium-nickel–cobalt-manganese oxide (Li[NixMnyCoz]O2, NMC). However, quantitative analysis based on Gaussian/Lorentzian (G/L) peak fitting suffers from the challenges of reproducibility and effectiveness. In this study, the Ni2+ and Ni3+ standard samples and a series of NMC samples with different Ni doping levels were synthesized. The Ni2+/Ni3+ ratios in NMC were quantitatively analyzed by non-linear least-squares fitting (NLLSF). Two Ni 2p overall spectra of synthesized Li [Ni0.33Mn0.33Co0.33]O2(NMC111) and bulk LiNiO2 were used as the Ni2+ and Ni3+ reference standards. Compared to G/L peak fitting, the fitting parameters required no adjustment, meaning that the spectral fitting process was free from operator dependence and the reproducibility was improved. Comparison of residual standard deviation (STD) showed that the fitting quality of NLLSF was superior to that of G/L peaks fitting. Overall, these findings confirmed the reproducibility and effectiveness of the NLLSF method in XPS quantitative analysis of Ni2+/Ni3+ ratio in Li[NixMnyCoz]O2 cathode materials.

In the present work, the electrochemical behavior and semiconducting properties of a tin alloyed ferritic stainless steel in simulated concrete solution in presence of NaCl were estimated by conventional electrochemical methods such as potentiodynamic polarization, electrochemical impedance spectroscopy, and capacitance measurement (Mott-Schottky approach). The surface passive film was analyzed by X-ray photoelectron spectroscopy. The results revealed a good agreement between pitting corrosion, electrochemical behaviour, and electronic properties. The p and n-type bilayer structure passive film were observed. The increase of Sn4+ oxide species in the passive film shows no beneficial effects on the pitting corrosion. In addition, the dehydration of the passive film was further discussed.

A series of CuCo2O4 nanostructures with different morphologies were prepared by a hydrothermal method in combination with thermal treatment. The morphology, structure and composition were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. As the electrode materials for supercapacitors, CuCo2O4 nanoneedles delivered the highest specific capacitance compared with other CuCo2O4 nanostructures. Electrochemical performance measurements demonstrate that the carbon layer can improve the electrochemical stability of CuCo2O4 nanoneedles. The CuCo2O4@C electrode exhibits a high specific capacitance of 1432.4 F g−1 at a current density of 1 A g−1, with capacitance retention of 98.2% after 3000 circles. These characteristics of CuCo2O4@C composite are mainly due to the unique one dimensional needle-liked architecture and the conducting carbon, which provide a faster ion/electron transfer rate. These excellent performances of the CuCo2O4@C electrode confirmed the material as a positive electrode for hybrid supercapacitor application.

The SnO2/NiO composites were synthesized by hydrothermal followed by calcination using metal-organic framework (MOF) consisting of the ligand of p-benzene-dicarboxylic acid (PTA) and the Sn and Ni center ions as sacrificial templates. The structure and morphology of Sn/Ni-based MOF and SnO2/NiO composites were characterized by XRD, SEM, TEM, FT-IR, TG, XPS and Brunauer-Emmett-Teller analysis. Sensing experiments reveal that the SnO2/NiO composite with the molar ratio of 9:1 not only exhibits the highest response of 14.03 that is 3 times higher than pristine SnO2 to triethylamine at 70 °C, but also shows good selectivity. Such excellent performance is attributed to the MOF-driven strategy and the formation of p-n heterojunctions, because the metal ions can be highly dispersed and separated in the MOFs and can prevent the metal ions aggregation during the MOF decomposition process. The work is a novel route for synthesis of gas sensing material.

The direct methanol fuel cell is a promising energy conversion device because of the utilization of the state-of-the-art platinum (Pt) anode catalyst. In this work, novel Pt/Ni2P/CNTs catalysts were prepared by the H2 reduction method. It was found that the activity and stability of Pt for methanol oxidation reaction (MOR) could be significantly enhanced while using nickel phosphide (Ni2P) nanoparticles as co-catalyst. X-ray photoelectron spectroscopy revealed that the existence of Ni2P affected the particle size and electronic distribution of Pt obviously. Pt/CNTs catalyst, Pt/Ni2P/CNTs catalysts with different Ni2P amount were synthesized, among which Pt/6%Ni2P/CNTs catalyst exhibited the best MOR activity of 1400 mAmg−1Pt, which was almost 2.5 times of the commercial Pt/C-JM catalyst. Moreover, compared to other Pt-based catalysts, this novel Pt/Ni2P/CNTs catalyst also exhibited higher onset current density and better steady current density. The result of this work may provide positive guidance to the research on high efficiency and stability of Pt-based catalyst for direct methanol fuel cells.

Single crystalline 128°Y-cut LiNbO 3 thin films with a thickness of 670 nm are fabricated onto Si substrates by means of crystal ion slicing (CIS) technique, adhesive wafer bonding using BCB as the medium layer to alleviate the large thermal coefficient mismatch between LiNbO 3 and Si, and the X-ray diffraction pattern indicates the exfoliated thin films have good crystalline quality. The LiNbO 3 thin films are modified by low energy Ar + irradiation, and the surface roughness of the films is decreased from 8.7 nm to 3.4 nm. The sputtering of the Ar + irradiation is studied by scanning electron microscope, atomic force microscope and X-ray photoelectron spectroscopy, and the results show that an amorphous layer exists at the surface of the exfoliated film, which can be quickly removed by Ar + irradiation. A two-stage etching mechanism by Ar + irradiation is demonstrated, which not only establishes a new non-contact surface polishing method for the CIS-fabricated single crystalline thin films, but also is potentially useful to remove the residue damage layer produced during the CIS process.

Carbon fibers (CFs) were grafted with methyl acrylic via Diels-Alder reaction at the different oil bath temperature effectively creating a carboxyl functionalized surface. The effect of grafting temperature on the surface morphology and functional groups of carbon fibers were investigated by FTIR, Raman spectroscopy, XPS and SEM respectively. The results showed that the optimal grafting temperature was 80 °C, and the relative surface coverage by carboxylic acid groups increased from an initial 5.16% up to 19.30% significantly improved the chemical activity without damaging the skin and core region of the carbon fibers. Mechanical property tests indicated that the shear and tensile strength of the sample with the grafting temperature of 80 °C (CFRP-3) increased obviously by 90.3% and 78.7%, respectively, compared with the pristine carbon fibers reinforced composite. Further, the sample CFRP-3 exhibited higher and more stable friction coefficient and improved wear resistance, while the wear rate decreased 52.7%, from 10.8 × 10 −6 to 5.1 × 10 −6 mm 3 /N m. The present work shows that grafting methyl acrylic via Diels-Alder reaction could be a highly efficient and facile method to functionalize carbon fibers for advanced composites.

The emergence of transition metal dichalcogenides (TMD) as an exciting class of materials with appealing potentials in electronic and optoelectronics has drawn intensive attention in the past few years. Herein, we report the fabrication of NiSe2, which has been predicted to be a promising candidate in the field of electrocatalyst, by direct selenylation of the nickel substrate after epitaxial growth of selenium on a nickel foil. With a combination of photoelectron spectroscopy (PES), X-ray diffraction (XRD), scanning electron microscopy (SEM) and density function theory (DFT) calculations, it is possible to identify the phase transition among the previously reported stable Ni-Se phases and the ultimate formation of NiSe2 species by external annealing at varying temperatures. While SEM reveals the morphology of NiSe2 film with flat terraces, XRD, XPS and DFT calculations demonstrate that NiSe2 is the relatively stable phase formed on the Ni substrate from the cohesive energy point of view. Furthermore, valence band spectra point out the nonmetallic level of these different Ni-Se compounds, agreeing well with literature reports. In the end, our report may indicate a feasible approach to synthesize the pure NiSe2 species under solution-free condition and an encouraging step forward towards non-noble electrocatalysts.

An asymmetric membrane for direct contact membrane distillation (DCMD) was first prepared with the ability to concentrate strongly acidic and alkaline solutions. The membrane was fabricated by a simple coating and non-solvent phase separation process. The successful preparation of the aramid-coated polyvinylidene fluoride (PVDF) asymmetric membrane was demonstrated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS) characterization. Furthermore, it was verified via contact angle measurements that this modified membrane had better acid and alkali resistance than the pristine PVDF membrane at an elevated temperature. During the DCMD process, the pH of the permeate side did not fluctuate significantly when solutions with different pH values were used as the feed solutions, thus also demonstrating the excellent separation efficiency of the modified PVDF membrane. Moreover, the modified PVDF membrane exhibited a higher concentration factor for acidic and alkaline solutions than the pristine membrane. Therefore, it is believed that the modified membrane has great potential for application in DCMD process with the concentration of acidic and alkaline solutions.

Titanium ions with different energies and doses were implanted into the M50 steel surface. In addition, titanium and nitrogen ion co-implantation was applied for comparison. The tribological properties and wear resistance of the implanted samples were characterized using a sliding friction tester, grazing incidence angle X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, surface profiler, Raman spectrometer, and nanoindentation tests. The results indicated that the compounds of the titanium ion–implanted samples mainly consisted of titanium and TiO2, CrN interstitial compounds formed after titanium and nitrogen ion co-implantation, thus generating an implantation layer that exhibited high nano-hardness and low wear rates. The linear contact sliding friction coefficient curves for the implantation samples were composed of an initial stage, ascent stage, and stable stage. The tribological properties effectively improved with increasing titanium ion implantation energies and doses. In addition, this beneficial effect became much more significant at a higher titanium ion dose. The titanium and nitrogen ion–co-implanted samples formed Fe2O3 and Fe3O4 tribo-oxide layers after the wear test, which were partially responsible for reducing the wear. The dominant wear mechanisms of the implanted samples were abrasive wear and oxidative wear.

Aluminum has shown promising application in reducing the high-entropy alloys’ weight and enhancing their mechanical properties. In this work, the impact of solid-solution aluminum on the corrosion behavior and film properties of FeCoCrNiAlx (x = 0.1, 0.3) high-entropy alloy in 0.5 M H2SO4 and 0.5 M HCl solutions was investigated by electrochemical measurement, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The results demonstrate that both of the high-entropy alloys exhibit an equiaxed grain structure with numerous annealing twins. FeCoCrNiAl0.3 alloy still remains the stable FCC substrate without any second phase precipitates. The increasing aluminum content can improve the corrosion resistance of FeCoCrNiAlx by simultaneously increasing Cr oxide content in the passive film and making it thicker in the H2SO4 solution. Nevertheless, the effect is negative in the HCl solution because chloride ions are inclined to combine with the Al-containing metastable ion complexes, which accelerates the dissolution of HEA.

The exploration of novel nanomaterials employed as substrate to construct glucose biosensors is still of significance in the field of clinical diagnosis. In this work, NiO/Mn 2 O 3 nanoflake arrays were synthesized by hydrothermal approach in combination with calcination process. As-prepared NiO/Mn 2 O 3 nanoflake arrays were utilized to construct electrochemical biosensors for glucose detection. NiO/Mn 2 O 3 nanoflake arrays were investigated systematically by scanning electron microscopy (SEM), X-ray diffractionmeter (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy, the formation mechanism of NiO/Mn 2 O 3 nanoflake arrays was proposed. As-prepared glucose biosensors based on NiO/Mn 2 O 3 nanoflake arrays were characterized by cyclic voltammgrams and chronoamperometry. The results indicated that glucose biosensors based on optimized NiO/Mn 2 O 3 nanoflake arrays exhibited a high sensitivity of 167.0 μA mM −1 Cm −2 and good anti-interference ability, suggesting the NiO/Mn 2 O 3 nanoflake arrays are an attractive substrate for the construction of oxidase-based biosensors.

In this work, xanthan gum (XG) was exploited as a novel dolomite depressant in the flotation separation of apatite from dolomite in sodium oleate system. The flotation performances and adsorption mechanism of XG towards apatite and dolomite were studied through flotation tests, adsorption capacity measurements, micro-heat tests, atoms density calculations and surface characterizations. Flotation results revealed that XG exhibited strong depression effect on dolomite but barely influenced the flotation of apatite. The results of zeta potential, infrared spectroscopy analysis, adsorption capacity measurements and micro-heat tests proved that XG trended to adsorb on dolomite other than apatite, which hindered the adsorption of NaOL on dolomite and rendered the surface hydrophilic. Atom density calculations indicated that the preferential adsorption of XG on dolomite was due to much more dense and active Ca sites on dolomite surface than that of apatite. XPS results suggested that XG was strongly adsorbed on dolomite surface by means of chelation between COOH or OH groups within XG and Ca sites on dolomite, while it was weakly adsorbed on apatite by hydrogen bonding between OH groups within XG and F atoms on apatite surface.

In order to solve the problem that pristine ZnO show little response to NO2 gas at room temperature, some methods have been used, e.g., introducing narrow-bandgap semiconductors and donor defects into ZnO. In this work, we adopt solution precursor plasma spray to deposit CuxO1-y@ZnO1-α hybrid coatings. Rapid heating and cooling as well as the reducing atmosphere provided by solution precursor plasma spray (SPPS) produce highly concentrated donor defects such as zinc interstitials and oxygen vacancies. X-ray photoelectron spectroscopy, photoluminescence spectroscopy and electron paramagnetic resonance confirmed that rich donor defects were present in the SPPS CuxO1-y@ZnO1-α coatings. Field emission-scanning electron microscopy images exhibited a highly porous nanostructure, and high resolution-transmission electron microscopy showed that there were large amounts of p-n heterojunctions in the nanocomposites. The light absorption of the SPPS CuxO1-y@ZnO1-α hybrids was extended up to the whole visible light region. With assistance of visible light illumination, the nanocomposites exhibited significant response to NO2 for concentrations below 1 ppm. A sensing mechanism of the CuxO1-y@ZnO1-α sensors was proposed.

In this paper, the passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solutions at different pH was evaluated by potentiodynamic measurements, electrochemical impedance spectroscopy. The composition of the passive film and surface morphology were investigated by X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), and scanning electron microscopy, respectively. The results reveal that metastable pitting susceptibility, stable pitting corrosion, and composition of the passive film are influenced by pH value. After long time immersion, a bilayer structure passive film can be formed in this environment. The appearance of molybdates on the outermost surface layer, further enhancing the stability of the passive film. Moreover, the good pitting corrosion resistance of 316L stainless steel in simulated concrete pore solution without carbonated is mainly due to the presence of high Cr/Fe ratio and molybdates ions within the passive film.

A self-healing Li-Al layered double hydroxide conversion coating (LCC) modified with aspartic acid (ALCC) was prepared on 6N01 Al alloy for corrosion protection. Scanning electron microscopy (SEM) showed that a compact thin film has been successfully formed on the alloy. X-ray diffraction (XRD) and FT-IR spectra proved that species of aspartic acid anions were successfully intercalated into LCC. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and neutral salt spray (NSS) testing showed that the resultant ALCC could provide effective corrosion protection for the Al alloy. During immersion of the ALCC-coated alloy in 3.5% NaCl solution, new film was formed in the area of artificially introduced scratch, indicating its self-healing capability. XPS results demonstrated that Cl- anions exchange partial Asp anions according to the change content of element on conversion coating. From the above results, the possible mechanism via exchange/self-assembly was proposed to illustrate the phenomenon of self-healing.

Simultaneous adsorption of Sr2+ and ReO4−, which are surrogates of 90Sr2+ and 99mTcO4−, on hexadecyl pyridinium (HDPy+)-modified montmorillonite (HDPy/Mt) was investigated. When the amount of HDPy+ corresponding to 0.92 times the cation exchange capacity (CEC) of Mt was added, the obtained composite (HDPy/Mt–0.92) showed considerable adsorption capacities for Sr2+ and ReO4−. Some HDPy+ desorbed from the Mt layer in the presence of ReO4−, providing negatively charged sites on the Mt surface for Sr2+ adsorption. The desorbed HDPy+ interacted with ReO4− and was trapped in the composite in the form of HDPy–ReO4, resulting in adsorption of ReO4−. At high initial concentrations of ReO4−, the HDPy configuration changed after adsorption because of the desorption–adsorption process, which was supported by X-ray diffraction. Based on the results of X-ray photoelectron spectroscopy, in the binary system (i.e., Sr2+ and ReO4−), Sr2+ uptake occurred in the interlayer space, while adsorption of ReO4− occurred on the external surface and probably in the interlayer space. Desorption–adsorption and ion exchange account for Sr2+ uptake, while adsorption of ReO4− was mainly attributed to desorption–adsorption. Compared with the one-adsorbate system, a synergistic effect of simultaneous adsorption of Sr2+ and ReO4− was found in the two-adsorbate system.

Electrospun LaCoO 3 and Ce(NO 3 ) 3 ·6H 2 O were used as precursors to synthesize CeO 2 /LaCoO 3 (SSI-LaCoCe) with high oxygen mobility by solid state impregnation. Besides, electrospinning and ball milling technologies were also adopted to prepare the other two La-Co-Ce oxides, which are denoted as ES-LaCoCe and BM-LaCoCe, respectively. The catalysts were evaluated for total benzene oxidation in comparison with bare electrospun LaCoO 3 and CeO 2 , and characterized by means of O 2 -TPSR, XRD, BET, TEM, H 2 -TPR, O 2 -TPD, and XPS. Relative to LaCoO 3 , an enhanced catalytic performance can be obtained for La-Co-Ce oxides. Importantly, the concentration of surface adsorbed oxygen species from the highest to the lowest is SSI-LaCoCe > BM-LaCoCe > ES-LaCoCe, which is in good agreement with the order of catalytic activity in terms of T 50 . The high oxygen mobility in SSI-LaCoCe can be connected with sufficient interaction between active LaCoO 3 and CeO 2 . On the other hand, O 2 -TPSR analysis match well with the catalytic behaviors of La-Co-Ce oxides. Moreover, the catalyst with the best performance, SSI-LaCoCe, also represents good thermal stability during the long-term continuous test.

High quality VO2 films with precisely controlled thickness were grown on p-GaN/sapphire substrates by oxide molecular beam epitaxy (O-MBE). Results indicated that a distinct reversible semiconductor-to-metal (SMT) phase transition was observed for all the samples in the temperature dependent electrical resistance measurement, and the influence of VO2 layer thickness on the SMT properties of the as-grown n-VO2/p-GaN based nitride-oxide heterostructure was investigated. Meanwhile, the clear rectifying transport characteristics originated from the n-VO2/p-GaN interface were demonstrated before and after SMT of the VO2 over layer, which were attributed to the p-n junction behavior and Schottky contact character, respectively. Moreover, the X-ray photoelectron spectroscopy (XPS) analyses confirmed the valence state of vanadium (V) in VO2 films was principally composed of V4+ with trace amount of V5+. The design and modulation of the n-VO2/p-GaN based heterostructure devices will benefit significantly from these achievements.

Single crystal SrTiO 3 (STO) wafers were annealed by XeCl laser (λ = 308 nm) with different fluences of 0.4 J/cm 2 , 0.6 J/cm 2 and 0.8 J/cm 2 , respectively. Ti/Pt electrodes were sputtered on the surface of STO wafer to form co-planar capacitor-like structures of Pt/Ti/STO/Ti/Pt. Current-Voltage measurements show that the leakage current is enhanced by increasing laser fluence. Resistive switching behavior is only observed in the sample annealed by laser with relatively high fluence after an electro-forming process. The X-ray photoelectron spectroscopy measurements indicate that the amount of oxygen vacancies increases with the increase of laser fluence. This work indicates resistive switching appears when enough oxygen vacancies are generated by the laser, which form conductive filaments under an external electric field.

The magnetic core-shell Fe 3 O 4 @Alg-La particles were fabricated successfully by a simple method of electro-coextrusion, and employed as an adsorbent for separation of fluoride from aqueous solution. Main factors affecting the removal of fluoride, including pH, adsorbent dosage, initial concentration, temperature and contact time were investigated. The adsorption isotherm and adsorption kinetics were studied to understand the adsorption process in detail. The experimental data were fitted well by the non-linear Freundlich isotherm and linear pseudo-second-order model, the maximum fluoride adsorption capacity was 45.230 mg/g at pH 4, 298.15 K. Thermodynamic parameters indicated that the fluoride adsorption process was feasible and spontaneous. The presence of other anions like Cl − , SO 4 2− , HCO 3 − and PO 4 3− had almost no effect on the fluoride adsorption. The adsorbent can be easily separated from the solution by a magnet. The magnetic core-shell Fe 3 O 4 @Alg-La particles before and after fluoride adsorption were studied by SEM, FTIR, EDX and XPS, which indicated that the adsorption mechanism may be related to electrostatic attraction and Lewis acid-base interaction.

Novel visible-light driven Z-scheme Ag 2 CrO 4 /g-C 3 N 4 composites with different contents of Ag 2 CrO 4 were fabricated by a facile chemical precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and photoelectrochemical measurements. Compared with individual g-C 3 N 4 and Ag 2 CrO 4 , the Ag 2 CrO 4 /g-C 3 N 4 composites displayed much larger photocatalytic activities for the photocatalytic degradation of methyl orange (MO) solution at room temperature under visible light irradiation (λ > 420 nm). Importantly, the optimum photodegradation rate constant of the Ag 2 CrO 4 /g-C 3 N 4 composite at a theoretical weight content of 8.0% Ag 2 CrO 4 for the photodegradation of MO was 0.0068 min −1 , which was 5.7 and 4.3 times higher than that of pure g-C 3 N 4 and Ag 2 CrO 4 , respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag 2 CrO 4 /g-C 3 N 4 interface imparted through the Z-scheme electron transfer. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions were thought to dominate oxidative species of the Ag 2 CrO 4 /g-C 3 N 4 composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism was proposed. This work may be useful for the rational design of new types of Z-scheme photocatalysts and provide some illuminate insights into the Z-scheme transfer mechanism for application in energy conversion and environmental remediation.

Rechargeable aqueous zinc-ion batteries (AZIBs) are emerging as promising candidates for large-scale energy storage systems because of their low cost and high safety. However, the slow migration rate and strong electrostatic repulsion of divalent Zn2+ put forward many requirements for the properties of cathode materials. Herein, we present an aluminium pre-intercalated orthorhombic V2O5 (Al0.2V2O5) as a new cathode material for AZIBs. The analyses of GITT, ex-situ XRD, TEM and XPS indicate that the Al0.2V2O5 electrode possesses a higher Zn2+ diffusion coefficient than V2O5. And, the pre-intercalated Al3+ can stabilize the crystal structure and prevent Zn2+ from being trapped in the lattice. Because of the above advantages, Al0.2V2O5 shows much-enhanced electrochemical performance including a high capacity of 448.4 mA h g−1 at 0.1 A g−1, excellent rate capability of 143.9 mA h g−1 at 10 A g−1 and impressive long-term cycling stability with a capacity retention of 61.4% after 5000 cycles at 5 A g−1. Furthermore, the Al0.2V2O5/Zn battery can provide a high energy density of 327.1 W h kg−1 at 0.1 A g−1 and a high power density of 5491.8 W kg−1 at 10 A g−1, which shows great potential in the applications of large-scale energy storage.

Controlling nanosheet size and understanding size-dependent surface oxidation are of quite importance for the nonlinear optical properties of two-dimensional materials. Herein, size-separation of WS2 nanosheets was prepared successfully using liquid phase exfoliation and a gradient centrifugation method. We confirmed the higher surface oxidation with the decrease of nanosheet size by both high-resolution X-ray photoelectron spectroscopy and Raman spectroscopy. To investigate the effect of size-dependent surface oxidation on nonlinear optical properties in WS2, Z-scan technique equipped with 800 nm femtosecond laser was used. We observed the conversion between saturable absorption and reverse saturable absorption in WS2 dispersions as well as the decrease of saturable absorption in WS2 films due to the increase of reverse saturable absorption contribution of WO3. Energy-level model based on type II WS2/WO3 heterostructure was put forth to understand nonlinear optical absorption of the oxidized WS2. The results show that charge transportation from WS2 to WO3 increases the reverse saturable absorption contribution in WO3 while decreases the saturable absorption in WS2. The results pave the way to design desirable nonlinear optical devices by controlling size with different level of surface oxidation.

High N-content uranium nitride of UN1.85 thin films were successfully fabricated by radio frequency magnetron deposition on Si substrate, and the samples were characterized by Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS), respectively. Furthermore, the in-situ oxidation of UN1.85 was carried out under UHV condition with controlled oxygen exposure, which yields insights into the initial oxidation behavior of UN1.85. A gradual oxidation of UN1.85 is identified, where the N is displaced by O resulting in the formation of a series of uranium oxy-nitrides under various oxygen exposures. Three characteristic U4f7/2 peaks locating at 378.6 eV, 379.9 eV and 380.4 eV are corresponding to different intermediate uranium oxy-nitrides, where the higher the U4f7/2 peak, the higher O content in the intermediate uranium oxy-nitrides. The intermediate uranium oxy-nitride with U4f7/2 peak at relative lower position is further oxidized to higher energy side by the gradual displacement of N by O. The U4f7/2 peaks at 380.4 eV could be originated from the overlap of uranium oxides and uranium oxy-nitrides with the least N content among the three intermediates mentioned above. The coexistence of U4O9 and other uranium oxides in higher states UO2+x on UN1.85 oxidized surface is further identified by Raman spectroscopy, where the former is characterized with vibration signals at ~460 cm−1 and ~630 cm−1. A three-layered model is applied for the description of the oxidized UN1.85 surface, and an excellent resistance of UN1.85 against ambient corrosion is proved, where the oxidized thickness on the UN1.85 sample exposed under laboratory ambience for 18 months is similar with that oxidized with 2000 L O2 exposure under UHV condition.

Superhydrophobic Fe film with hierarchical micro/nano papillae structures is prepared on C45 steel surface by one-step electrochemical method. The superhydrophobic surface was measured with a water contact angle of 160.5 ± 0.5° and a sliding angle of 2 ± 0.5°. The morphology of the fabricated surface film was characterized by field emission scanning electron microscopy (FE-SEM), and the surface structure seems like accumulated hierarchical micro-nano scaled particles. Furthermore, according to the results of Fourier transform infrared spectra (FT-IR) and X-ray photoelectron spectroscopy (XPS), the chemical composition of surface film was iron complex with organic acid. Besides, the electrochemical measurements showed that the superhydrophobic surface improved the corrosion resistance of carbon steel in 3.5 wt.% NaCl solution significantly. The superhydrophobic layer can perform as a barrier and provide a stable air–liquid interface which inhibit penetration of corrosive medium. In addition, the as-prepared steel exhibited an excellent self-cleaning ability that was not favor to the accumulation of contaminants.

The nitride surfaces of uranium were prepared by the surface glow plasma nitriding (SGPN) and plasma immersion ion implantation (PIII) methods. The initial oxidation behaviors of modified surfaces were studied by X-ray photoelectron spectroscopy (XPS). The SGPN on the uranium surface led to a single layer of uranium sesquinitride (U2N3), while the PIII on the surface resulted in a compound layer composed of U2N3 and uranium dioxide (UO2). The oxygen covered on these modified layers led to the formation of UO2 from U2N3 and U2N3 from UN. The oxidized nitrogen species were also observed on the two types of nitriding layers, with the discussion of the N–O coaction behaviors.

Hierarchical MgO microspheres assembled by numerous porous nanoplates were successfully obtained by annealing the precursors of magnesium carbonate hydroxide hydrate synthesized through a facile and cost-effective hydrothermal process at low temperature. The as-prepared products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller measurements. The fluoride removal performance of the hierarchical MgO microspheres was investigated. The adsorption isotherm could be well fitted in Freundlich model, and the adsorption capacity was over 115.5 mg/g at pH 7. The absorbent also showed high fluoride removal ability in a wide pH range of 2–10, which is favorable for practical application. The effect of co-existing anions on fluoride removal was also investigated. The result indicated that the fluoride adsorption capacity was influenced when carbonate, bicarbonate and phosphate existed above the concentration of 50 mg/g. In addition, the adsorption mechanism was investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. A novel hydroxyl and carbonate co-exchange mechanism has been proposed for the first time. It can be found that fluoride ions could replace the surface carbonates which formed by the reaction of MgO and the adsorbed CO 2 molecules, and then anchored on the MgO surface.

High quality pure phase VO2 films were deposited on p-GaN/sapphire substrates by pulsed laser deposition (PLD). A well-defined interface with dense and uniform morphology was observed in the as-grown VO2/p-GaN/sapphire heterostructure. The X-ray photoelectron spectroscopy (XPS) analyses confirmed the valence state of vanadium (V) in VO2 films was principally composed of V4+ with trace amount of V5+, no other valence state of V was detected. Meanwhile, a distinct reversible semiconductor-to-metal (SMT) phase transition with resistance change up to nearly three orders of magnitude was observed in the temperature dependent electrical resistance measurement, which was comparable to the high quality VO2 film grown directly on sapphire substrates. Our present findings will give a deeper insight into the physical mechanism behind the exotic characteristics of VO2/p-GaN heterostructure, and further motivate research in novel devices with combined functional properties of both correlated oxide and wide bandgap nitride semiconductors.

The reduction of cobalt (Co) catalyst supported on silica nanosprings for Fischer-Tropsch synthesis (FTS) has been monitored by X-ray photoelectron spectroscopy (XPS) and compared to FT catalytic activity. The cobalt is present in the starting catalyst as a Co3O4 spinel phase. A two-step reduction of Co3O4 to CoO and then to Co0 is observed, which is consistent with the results of H2-temperature programmed reduction. During the reduction the two steps occur concurrently. The deconvolution of the Co 2p core level state for the catalyst reduced at 385 °C and 1.0 × 10−6 Torr of H2 revealed signatures of Co0, CoO, and Co3O4. The reduction saturates at a Coo concentration of approximately 41% after 20 h, which correlates with the activity and lifetime of the catalyst during FTS testing. Conversely, at 680 °C and 10 Torr of H2, the catalyst is completely reduced after 10 h. The evolution of the Co d-band at the Fermi level in the valence band XPS spectrum definitively verifies the metallic phase of Co. FTS evaluation of the Co/NS catalyst reduced at 609 °C showed higher production rate (3-fold) of C6-C17 hydrocarbons than the catalyst reduced at 409 °C and is consistent with the XPS analysis.

In this work, a series of Cu 2 O–modified Bi 2 O 3 nanospheres with perfect visible-light catalytic activity were successfully synthesized via the two-step method. The obtained products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) surface area, UV–visible diffuse reflectance spectroscopy (UV–vis DRS), and X-ray photoelectron spectroscopy (XPS). In the catalysts of Cu 2 O–modified Bi 2 O 3 nanospheres, Cu 2 O was dispersed on the surface of Bi 2 O 3 nanospheres. All of Cu 2 O–modified Bi 2 O 3 nanospheres showed uniformly nanospheres with the size of 80–150 nm, and exhibited enhanced photocatalytic activity in the degradation of Rhodamine B. The higher BET surface area, the band gap narrowing, and the interfacial charge transfer effect were considered to cause the excellent photocatalysis of Cu 2 O loading Bi 2 O 3 samples. Furthermore, the possible photocatalysis mechanism was proposed.