Light-assisted rapid preparation of a Ni/g-C₃N₄ magnetic composite for robust photocatalytic H₂ evolution from water

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 4; no. 25 p.9998-10007; pp. 9998 - 10007
• Main Authors: Kong, Linggang, Dong, Yuming, Jiang, Pingping, Wang, Guangli, Zhang, Huizhen, Zhao, Na
• Format: Journal Article
• Language: English
• Published: 2016
• Subjects: carbon nitride; electrons; graphene; hydrogen; hydrogen production; magnetism; nickel; photocatalysis; photocatalysts; photoluminescence; solar radiation
• ISSN: 2050-7496
• DOI: 10.1039/c6ta03178a

The precise combination of graphitic carbon nitride (g-C₃N₄) and nickel compounds is greatly desirable for the development of robust and low-cost photocatalytic systems made of earth-abundant elements. Herein, a rapid light-assisted method is proposed to prepare effectively combined Ni/g-C₃N₄ composite photocatalysts. In this process, the Ni(0) was formed from the reduction of Ni(ii) by photogenerated electrons and was loaded on the electron outlet points of g-C₃N₄ within 30 min; the ratio of Ni/g-C₃N₄ can be adjusted by changing the amount of nickel salt added. When the loaded Ni was 7.40 wt%, a high photocatalytic H₂ production rate of 4318 μmol g⁻¹ h⁻¹ was obtained and no noticeable decrease in the photocatalytic H₂ evolution rate was observed after four runs for 48 h in an aqueous triethanolamine solution. Furthermore, the Ni/g-C₃N₄ composite photocatalyst presented the ability for sunlight-driven H₂ production of 4000 μmol g⁻¹ h⁻¹ under natural sunlight outdoors. In addition, the mechanism for the efficient and stable activity of the Ni/g-C₃N₄ hybrid photocatalyst was investigated in detail through photoelectrochemical experiments and steady-state photoluminescence spectra. It was found that Ni effectively prevented the recombination of the photogenerated electrons and holes of g-C₃N₄ and improved the H₂ evolution activity.