Chao Wang,Xiaoyan Cai,Ying Chen,Zhengdong Cheng,Xianglong Luo,Songping Mo,Lisi Jia,Pengcheng Lin,Zhi Yang
Aiming at improving photocatalytic hydrogen production with TiO 2 , a series of TiO 2 coupled with metal oxide nanoparticles have been prepared by a sol-gel method with a fixed molar ratio in various compositions. The photocatalysts were characterized by surface and bulk techniques (XRD, FESEM, HRTEM etc.) and UV–vis DRS method was employed to understand the optical properties. The as-prepared TiO 2 coupled with metal oxide was mainly present as anatase, and the anatase grain sizes were reduced comparing to that in bare TiO 2 , as evidenced by XRD analysis. By analyzing FESEM and DLS results, aggregations of all samples occurred in both dry powder and water suspension. H 2 TPR analysis revealed H 2 reduction properties of the samples. Among those, Ag 2 O-TiO 2 presented better dispersion stability in different environmental phases. Improved adsorption of the TiO 2 for UV–vis light was confirmed. Photoreforming H 2 production was improved by the addition of those metal oxides mainly due to the promotion of heterostructure formation where the generated heterostructures could enhance the separation of electrons and holes under UV–vis light. In particular, Ag 2 O-TiO 2 among the samples exhibited the best hydrogen production activities with the maximum quantum efficiency and light-to-hydrogen energy conversion efficiency of 3.02% and 1.15‰, respectively. Considering the effect of glycerol concentration for photoreforming over Ag 2 O-TiO 2 , the obtained hydrogen evolution rate fitted a typical kind of Langmuirian catalytic behavior. Langmuir-Hinshelwood-type kinetic model was employed to calculate the corresponding reaction rate constant and glycerol adsorption constant.
Wang Chao,Zhong Weilin,Peng Suqing,Zhang Jingtao,Shu Riyang,Tian Zhipeng,Song Qingbin,Chen Ying
Pickering emulsion offers a promising platform for conducting interfacial reactions between immiscible reagents; it is particularly suitable for hydrogen production by photoreforming of non-water soluble biomass liquid and water. Herein, Pt-promoted (001)-facet-dominated anatase TiO2 nanosheets were synthesized by a hydrothermal route associated with microfluidic technology for high activity and metal dispersion, and selective surface modification was carried out for preparing Janus particles. Photoreforming hydrogen production through n-octanol and water that formed O/W microemulsion with an average diameter of 540 µm was achieved to obtain amphiphilic catalyst. The as-prepared 2D Janus-type catalysts exhibited remarkably stable emulsification performance as well as photocatalytic activity. This finding indicates that triethoxyfluorosilane had negligible impact on the catalytic performance, yet provided a remarkable benefit to large specific surface area at microemulsion interface, thereby enhancing the H2 yield up to 2003 μmol/g. The cyclic experiments indicate that the decrease in cyclic performance was more likely to be caused by the coalescence of the microemulsion rather than the decrease in catalytic activity, and the microemulsion could be easily recovered by simply hand shaking to more than 96% of the initial performance.
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