Highly crystalline carbon nitride induced by ultralow dosage of sodium fluoride with pinning-docking mechanism

Yueyang Tan; Yayun Pu; Zhongyan Zhang; Yabin Jiang; Lei Zeng; Chao Cai; Lu Jia; Weiman Zhuang; Zongzhao Sun; Limin Huang

doi:10.1016/j.jcis.2025.01.186

Highly crystalline carbon nitride induced by ultralow dosage of sodium fluoride with pinning-docking mechanism

J Colloid Interface Sci. 2025 Jan 21:685:866-875. doi: 10.1016/j.jcis.2025.01.186. Online ahead of print.

Authors

Yueyang Tan¹, Yayun Pu², Zhongyan Zhang³, Yabin Jiang⁴, Lei Zeng⁵, Chao Cai³, Lu Jia³, Weiman Zhuang³, Zongzhao Sun⁶, Limin Huang⁷

Affiliations

¹ School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 China; Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055 China; School of Traffic and Environment, Shenzhen Institute of Information Technology, Shenzhen 518172 China.
² School of Optoelectronic Engineering, Chongqing University of Posts and Telecommunications, Chongqing 400065 China. Electronic address: puyy@cqupt.edu.cn.
³ Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055 China.
⁴ Institute of Precision Medicine, Jining Medical University, Jining 272067 China.
⁵ School of Chemical Engineering and Pharmacy, Hubei Key Lab of Novel Reactor & Green Chemical Technology, Key Laboratory of Green Chemical Engineering Process of Ministry of Education, Wuhan Institute of Technology, Wuhan 430072 China.
⁶ College of Chemistry and Chemical Engineering, Linyi University, Linyi 276000 China. Electronic address: sunzongzhao@lyu.edu.cn.
⁷ Department of Chemistry, Southern University of Science and Technology, Shenzhen 518055 China. Electronic address: huanglm@sustech.edu.cn.

PMID: 39870004
DOI: 10.1016/j.jcis.2025.01.186

Abstract

In the typical ionothermal synthesis of crystalline carbon nitride (CCN), alkali metal halides are usually used in large amounts. Here, we report a new method for synthesizing poly (heptazine imide) (PHI) using only a trace amount of NaF, which is 20 times less than the amount of NaCl typically required to achieve the PHI structure. Different from the prevailing view that salts function primarily as templates and chelating agents during polymerization, our research revealed the unique role that NaF plays in the polymerization of PHI. We propose a new formation mechanism, termed the "pinning-docking mechanism," in which fluoride (F) atoms and bidentate nitrogen atoms (N) coordinated to sodium (Na) atoms build a strong triangle configuration that synergistically promotes the formation of PHI. Calculations indicate that the highly electronegative F atom generates an effective electron flow within the N-metal-F complex, causing local electron reorganization and accordingly activating the N sites for H₂ evolution. The synergistic roles of Na and F atoms in NaF for synthesizing PHI cannot be replicated with either NaCl or NH₄F salts under low dosage conditions. The synthesized PHI structure exhibits an exceptional hydrogen evolution rate of 10.2 mmol h^-1 g_cat^-1, exceeding that of amorphous TCN₍₅₅₀₎ by 217 times. This work provides an economical method for CCN synthesis and explores the underlying role of NaF salt during polymerization, which can be valuable for designing highly crystalline carbon nitride materials.

Keywords: Crystalline carbon nitride; Hydrogen evolution; Pinning-docking mechanism; Poly (heptazine imide); Sodium fluoride.