Design and constructing of mutually independent crystal facet exposed TiO2 homojunction and improving synergistic effects for photoelectrochemical hydrogen generation and pollutant degradation

作者：Li, Mengyan; Liu, Hui^*; Song, Yanghang; Gao, Jiaojiao

来源：International Journal of Energy Research, 2018, 42(15): 4625-4641.

DOI：10.1002/er.4204

• exposed crystal facet
• homojunction
• photoelectrocatalysis
• TiO2

Constructing homojunctions of same semiconductors is an effective way to promote charge separation and thus to improve the photoelectrochemical (PEC) and photocatalytic H-2 generation performance, and specifically, crystal-facet exposed homojunction is considered as a very promising structure. Herein, a mutually independent crystal facet exposed TiO2 homojunction was fabricated through a two-step hydrothermal method with the consideration of morphology and built-in compacted bonding interaction for PEC water splitting. The as-prepared homojunction photocatalyst is composed of a similarly dendritic structure where the trunk is TiO2 nanobelts (NBs) array with exposed (101) facets, and the branch portion is ultrathin TiO2 nanosheets (NSs) with exposed (100) facets sequentially located on the side surface of TiO2 NBs. The one-dimension (1-D) TiO2 NBs provide a fast electron transfer pathway and are beneficial to the radial transmission of photo-generated carriers. And the ultrathin TiO2 NSs with a larger surface area can increase direct contact area with electrolyte, light-harvesting capability and then accelerate the water splitting process. Moreover, due to built-in compacted bonding interaction between two building blocks with mutually independent exposed facets and matched band structure, this unique homojunction structure can effectively accelerate the transmission of electrons and decrease the recombination rate of the photo-generated carriers at the interface of two building blocks, thereby increasing the separation efficiency of photo-generated carriers and simultaneously enhancing the density of photo-generated electrons and holes, which can be verified through the photocurrent responses and photoluminescence spectra of the as-prepared samples. As a result, the as-prepared TiO2 homojunction can not only increase adsorption and profoundly boost photocatalytic performance for decomposition of organic contaminants (rhodamine B), but also possess a higher PEC and photocatalytic H-2 generation performance compared with TiO2 NBs. This work offers a new idea to design and fabricate highly efficient TiO2 photocathode for hydrogen generation and degradation of organic pollutants.

• 出版日期2018-12
• 单位陕西科技大学