“The Easier the Better” Preparation of Efficient Photocatalysts—Metastable Poly(heptazine imide) Salts

Zupeng Chen, Aleksandr Savateev, Sergey Pronkin, Vasiliki Papaefthimiou, Christian Wolff, Marc Georg Willinger, Elena Willinger, Dieter Neher, Markus Antonietti, Dariya Dontsova

Research output: Contribution to journalArticlepeer-review

209 Scopus citations

Abstract

Cost-efficient, visible-light-driven hydrogen production from water is an attractive potential source of clean, sustainable fuel. Here, it is shown that thermal solid state reactions of traditional carbon nitride precursors (cyanamide, melamine) with NaCl, KCl, or CsCl are a cheap and straightforward way to prepare poly(heptazine imide) alkali metal salts, whose thermodynamic stability decreases upon the increase of the metal atom size. The chemical structure of the prepared salts is confirmed by the results of X-ray photoelectron and infrared spectroscopies, powder X-ray diffraction and electron microscopy studies, and, in the case of sodium poly(heptazine imide), additionally by atomic pair distribution function analysis and 2D powder X-ray diffraction pattern simulations. In contrast, reactions with LiCl yield thermodynamically stable poly(triazine imides). Owing to the metastability and high structural order, the obtained heptazine imide salts are found to be highly active photocatalysts in Rhodamine B and 4-chlorophenol degradation, and Pt-assisted sacrificial water reduction reactions under visible light irradiation. The measured hydrogen evolution rates are up to four times higher than those provided by a benchmark photocatalyst, mesoporous graphitic carbon nitride. Moreover, the products are able to photocatalytically reduce water with considerable reaction rates, even when glycerol is used as a sacrificial hole scavenger.

Original languageEnglish
Article number1700555
JournalAdvanced Materials
Volume29
Issue number32
DOIs
StatePublished - 25 Aug 2017
Externally publishedYes

Keywords

  • carbon nitride
  • glycerol oxidation
  • mesocrystals
  • poly(heptazine imide)
  • water reduction reactions

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