Hu Fengxian,Cui Entian,Liu Hongxia,Wu Jing,Dai Yong,Yu Guiyun
Series of Bi 2 MoO 6 /NiAl-LDH hetero-junction photocatalysts were synthesized by a two-step hydrothermal method with a self-assembled process. It indicated that the in-situ intercalated NiAl-LDH showed a tight contact with Bi 2 MoO 6 layers and thus exhibited the rapid transfer of photogenerated electrons on the interface. The photocatalytic performance was evaluated by the degradation of rhodamine B (RhB) under visible light irradiation. The resulted Bi 2 MoO 6 /NiAl-LDH sample showed a higher visible-light photocatalytic activity for the degradation of RhB than any single component. The optimal LDH content in Bi 2 MoO 6 /NiAl-LDH is 15% with the degradation efficiency for more than 90% during 60 min. The excessive amount of NiAl-LDH in Bi 2 MoO 6 /NiAl-LDH could reduce the light absorption efficiency of Bi 2 MoO 6 and thus affected the generation of photoinduced electron–hole pairs. The enhanced photocatalytic activity and stability of Bi 2 MoO 6 /NiAl-LDH was attributed to the synergistic effects of the introduction of narrow band-gap NiAl-LDH and the construction of layered hetero-junction. Our synthetic method of self-assembly sheets has certain guided significance for the synthesis and application of other photocatalysts.
Herein, we present the preparation of nano-TiO 2 –silicone resin composite films by double liquid phase spray deposition. The films exhibit better adhesion stability and photocatalytic activity under a hydrodynamic erosion condition than conventional nano-TiO 2 composite films. The TiO 2 layer morphology and effective TiO 2 coverage ratio (CR) were affected by the initial curing time (ICT) of the silicone resin, e.g., the increase in an ICT from 10 to 40 min resulted in a CR change from 79.1 to 98.7%. The surface morphology evolution of composite films was studied under a hydrodynamic erosion period of 4 weeks. Obtained results allowed the 4-week evolution to be divided into four stages (pitting, crack pregnant, banded stripping, and surface stripping periods), additionally revealed that the CR of all samples was remained above 65%. The photocatalytic activity of composite films before and after 4-week hydrodynamic erosion was evaluated by rhodamine B degradation experiments. The 4-week erosion only led to the decrease of the photodegradation efficiencies by less than 40% in all cases. Thus, the fabricated TiO 2 –silicone composite films demonstrated excellent durability and photocatalytic activity under the conditions of long-term hydrodynamic erosion, allowing one to conclude that this work paves the way to the fabrication of next-generation photocatalytic materials for industrial applications.
Doping has generally been served as one of the most efficient strategies for the improvement of wide band gap semiconductor photocatalysts . However, atomic arrangements of doped elements in the host crystal structure have often been overlooked, particularly during the investigation and evaluation of dopant functionality. It is known that electronic structures of a semiconductor are profoundly controlled by atomic occupancies in different crystallographic positions. Knowledge about dopant accommodations in the crystal structure and their influence towards photocatalytic performance is highly desired. Here, we investigated four compositional and structural relevant compounds CrNbO 4 , CrTaO 4 , Sr 2 CrNbO 6 and Sr 2 CrTaO 6 with the aim to study the effects of cation ordering/disordering upon their photocatalytic activity . Our results showed that ordered cations, namely Cr and Nb/Ta, are detrimental to the photocatalytic performance. Theoretical calculations indicate that cation ordering would enlarge the band gap and inhibit charge transfer between Cr and Nb/Ta. Our findings imply that ordered dopants in photocatalytic materials would severely offset the benefits of doping and might be a reason for the decreased activity at high doping levels often encountered.
Xiaoyun Chen,Dong-Hau Kuo,Dongfang Lu,Yongxuan Hou,Yen-Rong Kuo
Mesoporous TiO 2 was synthesized by a hydrolysis precipitation method with the utilization of the biological renewable resource of lignin as template and TiCl 4 as reactant. The photocatalytic activity of TiO 2 was investigated by the degradation of phenol under UV light irradiation. The microstructure, crystallinity , powder characteristic, and chemical bonding of the catalyst were analyzed. The 500 °C-calcined TiO 2 had average crystallite size of about 11.1 nm and a mesoporous structure with specific area of 165.8 m 2 /g and pore volume of 0.312 cm 3 /g. The results showed that TiO 2 synthesized with lignin template exhibited high photocatalytic activity, which can be attributed to the electronegativity and the network skeleton of lignin to uniformly distribute the TiO 2 precursor for forming TiO 2 mesoporous particles. The mechanism for the improved photodegradation of the lignin-assisted TiO 2 was proposed.
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