Preparation Of Carbon Material Modified Semiconductor Nanomaterials And Their Photocatalytic / Electrocatalytic Properties

Nowadays, water pollution and energy crisis are the two serious problems in the world that human beings need to solve. Photoelectrocatalystic technology, one of the most attractive techniques for enviormental pollution control, has been widely investigated. In the photoelectrocatalystic process, the used of the photoelectrode was benificical to generation of hydroxyl radicals(·OH) and other radicals which would destroy the organic pollutants to CO2 and H2 O. In the recent years, photoelectrocatalystic technology has been received considerable attention due to their strong oxidizability, fast oxidation rate and easily separated and reused.Due to its unique physical and chemical properties,nano-semiconductor is one of the most efficient material to deal with environment pollution. Recently, as supports in fuel cells, applications of nano-semiconductor have been reported. However, the lower catalytic activity, a poor visible light–response and the difficulty to separation and recovery of the traditional powdery photocatalyst hampers its practical application. To overcome the existing deficiencies(such as high recombination, poor visible-light activation, and low efficiency, et. al) of conventional powdery semiconductor photocatalyst materials, in this paper, a high catalytic activity, visible light–response semiconductor electrode material was fabricated, modified, and applied in organic pollutant degradation under photocatalytic or photoelectrocatalytic conditation. At the same time, the semiconductor materials as suitable supports of noble metal catalysts in the application of fuel cell were studied. The main research work in this paper is listed in the following:(1) The well–defined TiO2 nanospheres deposited on carbon cloth(CC) materials(TiO2/CC) were firstly fabricated via an in–situ deposition and calcination method. Furthermore, graphene oxide(GO) aqueous solution was directly added on the surface of TiO2/CC, then a one–step electrochemical reduction method was employed to obtain reduced graphene oxide(RGO) hybridized TiO2/CC(RGO/TiO2/CC) composites. It is interesting that the RGO/TiO2/CC composites show highly efficient visible–light photoelectrocatalytic activity toward the degradation of MB, a model pollutant employed in this work, with great stability and recyclability. Moreover, compared with electrochemical and photocatalytic processes, the efficiency of PEC process is also evidently improved, which might owing to a synergetic effect of photocatalysis and electrocatalysis in the PEC process. The investigation sheds light on developing novel, cost–effective yet highly efficient visible–light–active carbon materials-TiO2 hybrid catalysts for PEC degradation of organic pollutants.(2) Reduced graphene oxide(RGO) modified TNTs arrays by anodic oxidation in NH4 F organic electrolyte were synthesized and followed by vapor-thermal method. These graphene modified highly ordered TNTs arrays could be used as efficient photoelectrode for PEC degradation of methyl orange(MO) pollutants under visible light irradiation with great stability and cyclicity. Compared with the bare TNTs, RGO–TNTs catalysts displayed evidently enhanced PEC performance. Moreover, by comparison with electrochemical and photocatalytic process, the efficiency of PEC process was also evidently improved. This is owing to a synergetic effect of photocatalysis and electrocatalysis in the PEC process, which the recombination of generated electron–hole pair is suppressed by the external electric field. The investigation likely opens up new promise for developing novel, stable and highly efficient visible–light–driven graphene modified highly ordered TNTs–based catalysts for PEC degradation of organic pollutants.(3) In this work, we synthesized TNTs decorated with Pt nanoflowers(Pt–TNTs) and followed by modification of reduced graphene oxide nanosheets(Pt–TNTs/RGO). The ternary complex displays higher electrocatalytic performance of methanol oxidation compared to Pt nanoflowers decorated TNTs in an alkaline medium. Interestingly, the electrocatalytic activity and stability of methanol oxidation could be distinctly improved with assistance of visible light illumination. Both electro– and photo–catalytic processes for methanol oxidation contribute to the enhanced catalytic performance and stability. The present work might offer a new paradigm for developing efficient yet long–term stability catalysts for DMFCs application with assistance of visible–light illumination.(4) For the first time, a facile method to synthesize MoS2/graphene composites as supports for decorated Pt nanoclusters. It is found that well-dispersion of Pt nanoparticles with uniform size of 3.41 nm were decorated on the surface of MoS2/graphene sheets. Moreover, these nanocomposites display highly efficient electrocatalytic performance towards methanol oxidation under acid medium. Compared to commercial Pt/C species, Pt supported on the MoS2/graphene composites displays 5.65 times electrocatalytic methanol oxidation activity. The outstanding electrocatalytic performances confirm 2D MoS2/graphene as an ideal electrocatalyst support for the commercialization of fuel cells in future.