Enhanced photocatalytic N2 fixation by promoting N2 adsorption with a co-catalyst

Xiang Gao; Li An; Dan Qu; Wenshuai Jiang; Yanxiao Chai; Shaorui Sun; Xingyuan Liu; Zaicheng Sun

doi:10.1016/j.scib.2019.05.009

Enhanced photocatalytic N₂ fixation by promoting N₂ adsorption with a co-catalyst

Sci Bull (Beijing). 2019 Jul 15;64(13):918-925. doi: 10.1016/j.scib.2019.05.009. Epub 2019 May 16.

Authors

Xiang Gao¹, Li An², Dan Qu³, Wenshuai Jiang², Yanxiao Chai², Shaorui Sun², Xingyuan Liu⁴, Zaicheng Sun²

Affiliations

¹ State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; University of Chinese Academy of Sciences, Beijing 100190, China.
² Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory of Green Catalysis and Separation Department of Chemistry and Chemical Engineering, School of Environmental and Energy, Beijing University of Technology, Beijing 100124, China.
³ Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory of Green Catalysis and Separation Department of Chemistry and Chemical Engineering, School of Environmental and Energy, Beijing University of Technology, Beijing 100124, China. Electronic address: danqu@bjut.edu.cn.
⁴ State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China.

PMID: 36659756
DOI: 10.1016/j.scib.2019.05.009

Abstract

Photocatalytic N₂ fixation involves a nitrogen reduction reaction on the surface of the photocatalyst to convert N₂ into ammonia. Currently, the adsorption of N₂ is the limiting step for the N₂ reduction reaction on the surface of the catalyst. Based on the concept of photocatalytic water splitting, the photocatalytic efficiency can be greatly enhanced by introducing a co-catalyst. In this report, we proposed a new strategy, namely, the loading of a NiS co-catalyst on CdS nanorods for photocatalytic N₂ fixation. Theoretical calculation results indicated that N₂ was effectively adsorbed onto the NiS/CdS surface. Temperature programmed desorption studies confirmed that the N₂ molecules preferred to adsorb onto the NiS/CdS surface. Linear sweep voltammetry results revealed that the overpotential of the N₂ reduction reaction was reduced by loading NiS. Furthermore, transient photocurrent and electrochemical impedance spectroscopy indicated that the charge separation was enhanced by introducing NiS. Photocatalytic N₂ fixation was carried out in the presence of the catalyst dispersed in water without any sacrificial agent. As a result, 1.0 wt% NiS/CdS achieved an ammonia production rate of 2.8 and 1.7 mg L^-1 for the first hour under full spectrum and visible light (λ > 420 nm), respectively. The catalyst demonstrated apparent quantum efficiencies of 0.76%, 0.39% and 0.09% at 420, 475 and 520 nm, respectively. This study provides a new method to promote the photocatalytic efficiency of N₂ fixation.

Keywords: Co-catalyst; N(2) adsorption; N(2) fixation; NiS; Photocatalyst.