| Nowadays, the world is facing serious energy and environmental problems. Photocatalysis can promote reaction occuring at room temperature and use solar energy to drive the reaction. These unique properties make it possible to purify environment and produce clean energy. Air and water pollution are the main problems affecting human life and social progress, and hydrogen energy has been regarded as the most promising alternative energy resource in 21 st century. However, Ti O2 has the intrinsic drawbacks such as narrow absorption spectra, low utilization of solar light and the high recombination rate of photo-induced electrons and holes, thus severely limiting their practical application. Herein, multiple strategies have been developed toward solving those problems, such as building stable and efficient photocatalysts, designing novel photoelectric catalytic reactor, and achieving synergistic effects by combining photocatalysis and electrochemical techniques. The detailed research results are as follows:1. Synergistic integration of visible light photocatalysis and base-cocatalysis on CdS/Na2Ti3O7 composites for highly efficient NOx removalA visible-light driven CdS/Na2Ti3O7 efficient nanocomposite was synthesized by combining continuous phase sodium titanate nanosheets（Na2Ti3O7） with dispersed phase Cd S nanoparticles under mild hydrothermal conditions. TEM, EIS, NO-abs, CO2-TPD characterizations indicated the surface structure, electrochemical properties, adsorption properties, alkali catalytically active sites of the as-prepared composites, which gained an insight into the catalytic mechanism. The results showed that CdS/Na2Ti3O7 nanocomposites exhibited excellent photocatalytic activity in the oxidative reaction of NOx removal. This was because Na2Ti3O7 with unique twodimensional structure provided electronic transmission channels to avoid the combination of photo-generated holes and electrons, on the other hand, Na2Ti3O7 provideed basic active sites where can adsorp NO3- product on the catalyst surface to prevent the deactivation, and thereby these properities contributed to the enhancement of the catalytic activity and stability.2. Photoelectrocatalytic oxidation of NO: A novel reactor using an unconventional gas-phase photoelectrode driven by an electrochemical cellThe success in constructing a novel PEC reactor driven by an electrochemical cell, combined with an untraditional gas-phase photoelectrode, has enabled us to make systematic studies on working mechanisms of hydroxyl radicals and photo-generated holes in the PEC process for NO removal, which are very important information for air purification technologies. The studies have revealed that PEC is more effective than PC by using Ti O2-nanorods arrays/FTO as probe electrode with low bias voltage. Importantly, all the results have been explained on the basis of our proposed new mechanism that NO can be directly oxidized by VB holes, meanwhile the indirect NO oxidation by hydroxyl radicals can also be initiated at the presence of residue water. This work highlighted the potential application of PEC involving new gas-phase electrode in the field of photocatalytic environmental cleaning and energy conversion.3. A novel PEC reactor realizing multifunctional reactions all in one: simultaneously photoelectrocatalytic gaseous NOx removal and liquid MO pollutants removal together with photocatalytic H2 productionOn the basis of the PEC reactor for gas-phase pollutants removal, we designed a new PEC reactor which can realize multifuntioncal reactions involving two reaction phases, including simultaneously photoelectrocatalytic removal of liquid and gaseous pollutants（MO and NO） and photocatalytic H2 production. BiOBr nanosheets array films were synthesized by a microwave alcohol-thermal method, and the synthesis conditions were optimized, such as ratio of the solvents, temperature, heating rate etc. The surface structure, composition and electrical chemical and optical properties were studied by SEM, TEM, XRD, PC, UV-vis. In this novel reactor, BiOBr NSs were used as gas-phase anode and Ti O2 NTs were applied as liquid-phase anode and Pt sheet as the cathode. Such design achieved photoelectrocatalytic removal of gas/liquid phase pollutants（NO/MO） and hydrogen production simultaneously. |
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