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A hydrogenated Diamond-Like Carbon (DLC) film possesses an ultra-low coefficient of friction in a low-humidity environment and higher as the humidity increases. This is due to the presence of water molecules in the atmospheric environment that is physically adsorbed and forming a thick layer on the surfaces that inhibits the growth of carbonaceous transfer film. One viable solution for this problem is to dope fluorine into the hydrogenated DLC film to decrease its surface energy. Therefore, this study varies carbon tetrafluoride feed as a doping source on the hydrogenated DLC film produced via plasma-enhanced chemical vapor deposition on 304 stainless steel substrates. The film hardness, carbon hybridization, and surface hydrophobicity were evaluated using nano-indentation testing, Raman spectroscopy, and contact angle measurement respectively. The coefficient of friction was analyzed by utilizing a ball-on-disc tribometer at a controlled temperature and humidity. The findings suggest that with the increase of the fluorine, the film hardness decreased as the sp3/sp2 carbon ratio decreased because weaker C–F bonds are substituting the strong C=C bonds. The increase in fluorine was also observed to produce a more hydrophobic surface. The ball-on-disc test analysis shows that the coefficient of friction was significantly reduced as the C-F bond increased which enables the prevention of carbonaceous transfer film through the adsorption of the water molecule.

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• Fluorine-doping engineering was developed using NH 4 F and HF as precursors. • Fluorine doped Al 2 O 3 shows more oxygen vacancy defects and strong Lewis acid sites. • NF-Al 2 O 3 /O 3 system selectively degrades electron-rich pollutants with high environment tolerance. • It's feasible to reuse the dyeing & finishing wastewater after purification by NF-Al 2 O 3 /O 3 system. Manipulating the electron density of active sties to develop highly efficient catalysts is expected to be one of the most ideal approaches to facilitate overall efficiency of the heterogenous catalytic ozonation (HCO) process. In this study, we demonstrate a fluorine-doping engineering to optimize the HCO activity of aluminum oxide through an improved sol–gel method using NH 4 F (NF-Al 2 O 3) and HF (HF-Al 2 O 3) as the fluorine source. We provide evidence that the fluorine atom is successfully incorporated into crystal structure of NF-Al 2 O 3 via the formation of Al-F-Al bonds, accompany with the generation of oxygen vacancy defects, which allow for ozone molecule adsorption and activation. In contrast, the fabricated HF-Al 2 O 3 only features the presence of Al x F y ·nH 2 O instead of Al-F-Al structure probably due to the unexpected etching reaction. The introduction of fluorine atom largely decreases the local electron density of neighboring Al of NF-Al 2 O 3 catalyst evidenced by the two-fold increment in the amount of strong Lewis acid sites. Consequently, the HCO activity of NF-Al 2 O 3 catalyst is found promotion by 42.9% over pure Al 2 O 3 in terms of the degradation kinetic rate constant (k obs). The NF-Al 2 O 3 catalyst exhibits a powerful capacity to selectively catalyze ozone molecule into singlet oxygen (1O 2), rendering the HCO system with high-tolerance to coexisting water matrixes (e.g., humic acid, chlorine ions, carbonate). Moreover, NF-Al 2 O 3 initiated HCO system can effectively purify wastewaters from textile industry with high-quality enough to be reused for textile dyeing. Therefore, our study provides a novel strategy to develop effective HCO catalysts for promoting wastewater treatment and reuse. [ABSTRACT FROM AUTHOR]

Fluorine-doped tungsten oxide (WO3) plate-like films were synthesized by hydrothermal radio-frequency (RF) sputtered tungsten (W) thin films in HF solution. The crystal structure, composition and morphology of nitrogen fluorine (F) doped WO3 were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectra (DRS) techniques. The results indicate that fluorine can be doped successfully into WO3 plate-like films by hydrothermal synthesis in hydrofluoric acid (HF) solution. The F-doped WO3 samples show stronger absorption in the UV-Vis range and a red shift in the band gap transition. Incident photon to current efficiency (IPCE) measurements carried out on photoelectrochemical cell with F-doped WO3 plate-like films as anodes demonstrate a significant increase of photoresponse in the visible region compared with undoped WO3. The photocatalytic activity under visible light irradiation for newly synthesized F-doped WO3 plate-like films was investigated by degradation of methyl orange. The photocatalytic activity of F-doped WO3 plate-like films was 3-fold enhancement compared with pure WO3 samples. Fluorine-doped tungsten oxide (WO3) plate-like films were synthesized by hydrothermal RF (radio-frequency) sputtered tungsten (W) thin films in HF solution. The F-doped WO3 samples show stronger absorption in the UV-visible range and a red-shift in the bandgap transition. The photocatalytic activity of F-doped WO3 plate-like films was three-fold enhancement compared with pure WO3 samples. [ABSTRACT FROM AUTHOR]

The F doping effects on the electronic structure and magnetic properties of CrO 2 have been studied using the first principles projector-augmented wave potential within the GGA+ U . The F-doped CrO 2 with low F concentration keeps a high spin polarization. Due to F doping, five different Jahn–Teller structural distortions are observed for the octahedrons around five groups Cr atoms in F-doped CrO 2 , this results from the 3 d electron orbitals are asymmetrically occupied. Compared with pure CrO 2 , the decrease of spin polarization of F-doped CrO 2 is contributed by the shift of Cr IB 3 d state towards low energy region. The impurity moment by substituting F impurities for O atoms are aligned with the host moment and the total magnetic moment increase about 1 μ B by more substituting one F impurity for one O atom, indicating that magnetic moment can be controlled by F doping. For Cr 54 O 102 F 6 , Cr IIA and Cr IIB alternately arrange in a unbroken F–Cr–F zigzag chain along the 〈 111 〉 direction in the ( 1 1 ¯ 0 ) plane, but the additional magnetic moment by substituting F impurity for O does not appear to reside on the Cr ion in the vicinity of the F impurity, but is quite diffuse due to the magnetic double-exchange interaction. [ABSTRACT FROM AUTHOR]

Single-atom catalysts have attracted enormous research interest in the field of catalysis owing to their remarkable catalytic activity, excellent stability and outstanding atom utilization. Herein, a new single atom based on single Fe atoms on fluorine-doped (Fe–SAs@FNC) ultrathin carbon nanosheets was successfully synthesized by a polymer-assisted heating method. Experimental evidence showed that the resultant Fe–SAs@FNC with Fe–N 4 sites exhibits superior peroxidase-like activity, which oxidizes the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to produce a blue product in the presence of hydrogen peroxide (H 2 O 2). Based on this, an ultrasensitive and highly selective colorimetric detection method for p -phenylenediamine (PPD) in hair dyes and PPD in hair after dyeing was established, which had a wide linear range (0.2–50 μM) and low detection limit (0.07 μM). This method shows satisfactory sensitivity and selectivity. [Display omitted] • High catalytic activity Fe–SAs@FNC was synthesized by a polymer-assisted heating method. • F doping uniformly dispersed the active sites of Fe–SAs@FCN. • The peroxidase-like activity of Fe–SAs@FNC with Fe–N 4 sites is better than that of other reported Fe-based nanozymes. • There is a satisfactory linear range of 0.2–50 μM, and the limit of detection (LOD) is 0.07 μM. [ABSTRACT FROM AUTHOR]

Abstract: Fluorine-doped nanocrystalline TiO2 powders with controlled anatase–rutile phase content are synthesized by a sol–gel route using NH4F and CF3COOH as fluorine sources. The X-ray diffraction (XRD) study reveals that fluorine-doping through NH4F leads to the formation of anatase crystalline phase, whereas F-doping through CF3COOH favors the formation of rutile along with anatase phase. These results are connected to the influence of the fluorine precursor on the pH of the starting solutions. The presence of the fluorine in the powders is confirmed using X-ray photoelectron spectroscopy (XPS). The dopant in concentrations between 11 and 16at.% is found mainly in the form of metal fluoride. The measured UV–vis diffuse reflectance spectra and the calculated band gap widths using Kubelka–Munk phenomenological theory are in good agreement with the crystallographic results. The calculations reveal no change in the band gap values due to fluorine doping. The enhanced absorbance in the vis region and the red shift of the absorption edge are attributed to the presence of fluorine and the anatase/rutile phase composition of the TiO2 powders. [Copyright &y& Elsevier]

Abstract: A novel and simple method for preparing F-doped anatase TiO2 (defined as FTO) film with high photocatalytic activity was developed using titanium-n-butoxide and NH4F as TiO2 and fluorine precursors under mild condition, i.e. low temperature (lower than 373K) and ambient pressure. The prepared samples were characterized by XRD, SEM, X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectrum (DRS), photoluminescence spectrum (PL) and TG–DSC analysis. The photocatalytic activity was evaluated by decomposing X-3B under artificial solar light. The results showed that the crystallinity of TiO2 was improved by F-doping. F− ions can prevent the grain growth, and the transformation of anatase to rutile phase was also inhibited. The doped fluorine atoms existed in two chemical forms, and the ones incorporated into TiO2 lattice might take a positive role in photocatalysis. Compared with surface fluorination samples, FTO film exhibited better photocatalytic activity. The high photocatalytic activity of FTO may due to extrinsic absorption through the creation of oxygen vacancies rather than the excitation of the intrinsic absorption band of bulk TiO2. Furthermore, the FTO can be recycled with little photocatalytic activity depression. Without any further treatment besides rinsing, after 6 recycle utilization, the photocatalytic activity of FTO film was still higher than 79%. [Copyright &y& Elsevier]

Abstract: The electrocatalytic properties of PbO2 may be increased by incorporation of some ions such as F−. In this review, the preparation of fluorine-doped PbO2 in the presence of some additives of fluorine-containing compounds (F−, potassium salt of nonafluoro-1-butanesulfonic acid C4F9O3SK and Nafion®) is reported. The mechanism of electrodeposition is discussed. The amount of additives in the deposit depends on the experimental conditions: potential, current density and charge of additive species in the plating solution. The physicochemical properties of doped oxide are very different from those of undoped oxide, accounting for the different electrocatalytic activity of the materials. [Copyright &y& Elsevier]

Well-designed hierarchical F-BiVO 4 @NiFe-LDH photoanode with a core-shell heterostructure has been successfully fabricated by F− ions etching and in situ electrochemical synthesis of NiFe-LDH onto BiVO 4 film, which demonstrates enhanced photoelectrochemical water splitting and degrada antibiotic tetracycline hydrochloride. • F-BiVO4@NiFe-LDH photoanode has been successfully developed by surface/interface engineering. • The photoanode exhibits efficient performance in PEC water splitting coupled with degradation of organic pollutants. • Experimental studies and DFT calculation reveal a synergistic effect of F doping and NiFe-LDH cocatalyst. • This strategy can be extended to other photoelectrodes for solar energy conversion and wastewater treatment. Antibiotic resistance has become a global problem as indicated by the worldwide emergence of multidrug-resistant bacteria, which makes it an urgent demand to develop effective technologies for antibiotics removal from pharmaceutical wastewater. In this work, simultaneously removing antibiotic tetracycline from wastewater coupled with pure H 2 generation has been successfully achieved through PEC technique by using F-doped BiVO 4 @NiFe-LDH (F-BiVO 4 @NiFe-LDH) core-shell photoanode. The maximum photocurrent density of the F-BiVO 4 @NiFe-LDH photoanode at 1.23 V vs. RHE is about 6-fold that of the pristine BiVO 4 photoelectrode. Furthermore, the composite photoanode was effectively applied to the PEC degradation of tetracycline hydrochloride (TCH), superior to the reported results. An experimental-computational combination study reveals that the synergistic effect between F doping and NiFe-LDH simultaneously improves the light absorption, charge separation and charge injection efficiency of BiVO 4. This work presents a sunlight-driven, efficient and sustainable method for water splitting to produce hydrogen and new insights into wastewater treatment. [ABSTRACT FROM AUTHOR]

Sn-based composites have been considered as hopeful anode materials for lithium-ion batteries (LIBs), which is assigned to its high theoretical capacities, whereas the practical application has been limited by the poor stability. Herein, a novel fluorine-doped porous SnO2@C (SnO2@C–F) nanosheets has been developed by a facial balling method with the NaCl template. The porous SnO2@C–F nanosheets sample shows an outstanding electrochemical capacity (821mAhg−1 at 200mAg−1 after 100 cycles), excellent rate capacity (816.62, 684.46, 579.2, 476.08, 410.94, 361.64, 324.1 and 734.0 mAhg-1 at 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 A g−1, respectively) and long-term cycling stability (419.4 mAhg−1 even at 2.0 Ag-1 after 800 cycles). The enhanced electrochemical performance for the porous SnO 2 @C–F nanosheets is ascribed to the formed metal fluorides (Sn–F bond) and a strong electronic coupling between F-doped carbon and SnO 2 nanoparticles, while can greatly enhance the structure stability and electronic conductivity of SnO 2 anode materials. • SnO 2 @C–F nanosheets has been synthesized by balling method with assistance of NaCl. • The porous structure of SnO 2 @C–F nanosheets can facilitate lithium-ion transport. • The porous structure of SnO 2 @C–F nanosheets can withstand high stress during cycling. • SnO 2 @C–F nanosheets shows better rate capability and cycling stability. [ABSTRACT FROM AUTHOR]

• MgZnO:F films with high Mg content were synthesized by RF magnetron co-sputtering. • Structural, electrical and optical properties of the films were investigated. • F occupied O sites, decreased the resistivity without reducing optical loss. • Low resistivity and high carrier concentration were simultaneously realized. Fluorine-doped Mg 0.21 Zn 0.79 O (MZO:F) thin films were successfully deposited on glass substrates at room temperature by radio frequency (RF) magnetron co-sputtering method with Mg 0.21 Zn 0.79 O, MgF 2 , and ZnF 2 targets. Low resistivity (1.26 × 10-1 Ω⋅cm), high Hall mobility (3.55 cm2/Vs) and high carrier concentration (1.39 × 1019 cm−3) were simultaneously realized in the annealed MZO:F film. The effects of doping concentration and annealing temperature on the structural, morphological, electronic, electrical and optical properties of MZO:F films were systematically investigated in this study. XRD and XPS analysis confirmed that F atoms have entered into crystal lattices of MZO and acted as donors when they occupied O sites in the hexagonal lattice. Moreover, it was observed that both doping concentration and annealing temperature greatly affected the crystallinity, grain size, growth orientation and surface morphology of the MZO:F thin films. In addition, the optical gap changed dramatically with the F content and annealing temperature, which could be attribute to the Burstein-Moss effect accompanied by the effects of fluctuating potential arising from the randomly situated impurities. [ABSTRACT FROM AUTHOR]