Enhanced photocataly tic activity of TiO_2 by surface fluorination in degradation of organic cationic compound

Experiments were carried out to investigate the influence of TiO2 surface fluorination on the photodegradation of a representative organic cationic compound, Methylene Blue （MB）. The eleetropositive MB shows poor adsorption on TiO2 surface; its degradation performs a HO. radical-mediated mechanism. In the F-modified system, the kinetic reaction rate enlarged more than 2.5 fold that was attributed mainly to the accumulating adsorption of MB and the increased photogenerated hole available on the F-modified TiO2 surface.

A simple photochemical method for surface fluorination using perfluoroketones

Surface fluorination of conventional polymers can give them desirable surface properties similar to the expensive and difficult-to-process fluoropolymers.However,traditional surface fluorination techniques often require toxic reagents and special equipment.Here,we report a simple and effective polymer surface fluorination method by using safe and inexpensive perfluoro-2-methyl-3-pentanone(PFMP,C_(2)F_(5)C(=O)CF(CF_(3))_(2))and UV irradiation.This method is applicable to various polymer materials,and generates nanometer-thick fluorinated layer on the outermost surface,significantly changing their surface properties without changing the surface morphology.

Stable cycling of LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)/lithium metal batteries enabled by synergistic tuning the surface stability of cathode/anode

Ni-rich layered oxides(LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2))show great potential in long-range and low-cost lithiumion batteries.However,due to the high surface sensitivity,their practical application is hindered by interfacial instability with electrolytes under high voltage for long cyclic life.Herein,by combining both firstprinciple calculations and time-of-flight secondary ion mass spectrometry(TOF-SIMS),a novel surface fluorinated reconstruction(SFR)mechanism is proposed to improve the interfacial stability under high voltage,which could effectively regulate the surface fluoride species to desensitize the LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)interface.We demonstrate here that by tuning the ratio of fluoride species,the LiNi_(0.9)Co_(0.05)Mn_(0.05)O_(2)/Li battery could achieve excellent long-term and high voltage performance(163.5 mA h g^(-1)at 0.5 C for 300 cycles under 4.4 V),while the controlled sample decayed to 125.4 mA h g^(-1)after 300 cycles.Moreover,the favorable cross-talk effect induced by SFR further facilitates the incorporation of suitable amounts of Ni ions into the construction of stable solid electrolyte interface(SEI)layer for anode surface.Therefore,the ultra-long cycling stability under high voltage can be achieved by the robust cathode/electrolyte and Li/electrolyte interfaces,which results in excellent interfacial stability after long cycling.This work provides new insights into the surface design of cathode materials and improves the stability of the electrode-electrode interface under high voltage.

Strategies for synthesizing non-bioaccumulable alternatives to PFOA and PFOS

This minireview describes the strategies for synthesis of fluorinated surfactants potentially non- bioaccumulable. Various strategies have been focused on （Ⅰ） reducing the length of the perfluorocarbon chain, （Ⅱ） introducing hereto atoms into the fluorocarbon chain, （Ⅲ） introducing branch （herein and after branch means the fluoro-carbon chain section is not straight）. In most cases, the surface tensions versus the surfactant concentrations have been assessed. These above strategies led to various highly fluorinated （perfluorinated or not perfluorinated） surfactants whose chemical changes enabled to obtain novel alternatives to perfluorooctanoic acid （PFOA） and perfluorooctane sulphonate （PFOS）.