Facile preparation of novel nickel sulfide modified KNbO3 heterojunction composite and its enhanced performance in photocatalytic nitrogen fixation

Wenqian Zhang; Pingxing Xing; Jiayu Zhang; Lu Chen; Jieyu Yang; Xin Hu; Leihong Zhao; Ying Wu; Yiming He

doi:10.1016/j.jcis.2021.01.086

Facile preparation of novel nickel sulfide modified KNbO₃ heterojunction composite and its enhanced performance in photocatalytic nitrogen fixation

J Colloid Interface Sci. 2021 May 15:590:548-560. doi: 10.1016/j.jcis.2021.01.086. Epub 2021 Feb 1.

Authors

Wenqian Zhang¹, Pingxing Xing¹, Jiayu Zhang¹, Lu Chen², Jieyu Yang², Xin Hu¹, Leihong Zhao³, Ying Wu¹, Yiming He⁴

Affiliations

¹ Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China.
² Department of Materials Science and Engineering, Zhejiang Normal University, Jinhua 321004, China.
³ Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China. Electronic address: zhaoleihong@163.com.
⁴ Department of Materials Science and Engineering, Zhejiang Normal University, Jinhua 321004, China; Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, China. Electronic address: hym@zjnu.cn.

PMID: 33581658
DOI: 10.1016/j.jcis.2021.01.086

Abstract

This work was designed to prepare a novel NiS/KNbO₃ p-n heterojunction composite for efficient photocatalytic nitrogen fixation under simulated sunlight. The NiS/KNbO₃ photocatalyst was prepared through a two-step hydrothermal method. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses proved that NiS nanoparticles were closely decorated on the surface of KNbO₃ nanorods, to facilitate the migration of electrons between the two semiconductors. Mott-Schottky analysis indicated that the Femi level of KNbO₃ is higher than that of NiS. Thus, the electron migration from KNbO₃ to NiS occurs naturally. This migration elevates the band potential of NiS, makes NiS/KNbO₃ form a type-II photocatalyst, and generates an internal electric field in the composite. The synergetic effect of the internal electric field and the type-II band structure endows NiS/KNbO₃ with high efficiency in the spatial separation of photogenerated electron-hole pairs, verified by electrochemical impedance spectroscopy and transient photocurrent experiments. Therefore, NiS/KNbO₃ presents good efficiency in photocatalytic N₂ reduction with an NH₃ production rate of 155.6 μmol·L^-1·g^-1·h^-1, which is 1.9 and 6.8 times higher than those of KNbO₃ and NiS, respectively. UV-visible diffuse reflectance spectroscopy and N₂-adsorption experiments were also performed to investigate the effect of light absorption and surface area on the photocatalytic reaction. Nevertheless, compared with the great promotion effect in charge separation, the contribution of the two factors can be ignored.

Keywords: NiS/KNbO(3); P-n heterojunction; Photocatalytic N(2) fixation; Simulated sunlight.