Synergy of palladium species and hydrogenation for enhanced photocatalytic activity of {001} facets dominant TiO 2 nanos
- PDF / 711,191 Bytes
- 9 Pages / 584.957 x 782.986 pts Page_size
- 6 Downloads / 127 Views
Bing Liu, Ran Wang, and Lihong Tiana),b) Hubei Collaborative Innovation Center for Advanced Organochemical Materials and Ministry of Education Key Laboratory for the Synthesis and Applications of Organic Functional Molecules, Hubei University, Wuhan 430062, China (Received 20 April 2017; accepted 24 May 2017)
{001} facets dominant TiO2 nanosheets have attracted intensive attention in the photocatalytic field, due to their undercoordinated Ti5c centers, higher surface energy, and photocatalytic activity than those of any other low-energy facet. However, a fluorine-rich (001) surface is controversial to the photocatalytic activity of TiO2 nanocrystals. We have removed the surface F atoms bonding with Ti by hydrogenation method successfully, and found that {001} facets dominant TiO2 nanosheets without the terminated F atoms showed dramatic enhancement in the photocatalytic activity. Moreover, the clean (001) surface was more in favor of the deposition of PdO than the fluorine-rich surface, and the amorphous structure from the hydrogenation is beneficial to the reduction of PdCl42 to Pd nanoparticles. The PdO attached on {001} facets and the amorphous structure promoted the separation of charge carriers, and Pd nanoparticles transferred plasmonicinduced electrons to the conduction band of hydrogenated TiO2 under simulated solar irradiation. Thus, a significantly enhanced photocatalytic activity of Pd–H–TiO2 is achieved on degrading organic environmental pollution, due to the synergy of palladium species and hydrogenation on {001} facets exposed TiO2.
I. INTRODUCTION
Utilization of solar energy and semiconductor photocatalysis techniques are promising in solving the energy crisis and environmental pollution.1,2 Since Honda and Fujishima reported the breakthrough of photocatalytic hydrogenation evolution by TiO2 under ultraviolet (UV) light,3 thousands of papers have witnessed the development of TiO2 in the fields of photovoltaic, solar cell, CO2 reduction, photocatalytic hydrogen or oxygen production, etc.,1,2,4–6 as well as photocatalytic degradation of the environmental contaminants, due to its environmental friendliness, low cost, and its utilization of solar energy.5–7 It is known that photocatalytic reactions occurring on the surface of catalysts and TiO2 crystals with different types of exposed facets usually exhibit different physical and chemical properties. Theoretical calculations testified that the order of the average surface energy of anatase TiO2 is 0.90 J/m2 for {001} . 0.53 J/m2 for {100} . 0.44 J/m2 for {101}.8 A natural anatase crystal typically exhibits Contributing Editor: Xiaobo Chen a) Address all correspondence to this author. e-mail: [email protected] b) These authors contributed equally to this work. DOI: 10.1557/jmr.2017.232
(101), (100)/(010), and minority (001) surfaces, ascribed to the thermodynamic instability of (001) facets with the highest surface energy.9 Recently, a selective increase in the fraction of {001} facets in TiO2 crystals has been extensively reported,8–11 due to the fact th
