Water‐Soluble Polymeric Carbon Nitride Colloidal Nanoparticles for Highly Selective Quasi‐Homogeneous Photocatalysis

Igor Krivtsov,Robert Leiter,Andrey Turchanin,Luís Mafra,Chunyu Li,Christiane Adler,Dariusz Mitoraj,Christof Neumann,Radim Beranek,Johannes Biskupek,Benjamin Dietzek,Changbin Im,Björn Kirchhoff,Marina Ilkaeva,Timo Jacob,Ute Kaiser,Mariana Sardo

doi:10.1002/ange.201913331

Abstract

AbstractHeptazine‐based polymeric carbon nitrides (PCN) are promising photocatalysts for light‐driven redox transformations. However, their activity is hampered by low surface area resulting in low concentration of accessible active sites. Herein, we report a bottom‐up preparation of PCN nanoparticles with a narrow size distribution (ca. 10±3 nm), which are fully soluble in water showing no gelation or precipitation over several months. They allow photocatalysis to be carried out under quasi‐homogeneous conditions. The superior performance of water‐soluble PCN, compared to conventional solid PCN, is shown in photocatalytic H2O2 production via reduction of oxygen accompanied by highly selective photooxidation of 4‐methoxybenzyl alcohol and benzyl alcohol or lignocellulose‐derived feedstock (ethanol, glycerol, glucose). The dissolved photocatalyst can be easily recovered and re‐dissolved by simple modulation of the ionic strength of the medium, without any loss of activity and selectivity.

Highlights

Since the discovery of the photocatalytic activity of polymeric carbon nitride (PCN),[1] numerous top-down[2]and bottom-up[3] synthetic strategies aiming to disrupt the strong hydrogen bonding and van der Waals stacking in bulkPCN have been reported
Synthesis and Characterization presence of hydroxides in the melt catalyses the condensation of melamine, reducing the synthesis temperature of Figure 1 shows a schematic representation of the synthesis poly(heptazine imide) to 330 8C
The structure of the prepared ca. 12 mmol melamine) in the synthesis yields mostly solid K-PHI-S and dried K,Na-PHI samples is confirmed insoluble potassium poly(heptazine imide) (K-PHI-S)

Summary

Introduction

Since the discovery of the photocatalytic activity of polymeric carbon nitride (PCN),[1] numerous top-down[2]and bottom-up[3] synthetic strategies aiming to disrupt the strong hydrogen bonding and van der Waals stacking in bulkPCN have been reported. Na+ ions will promote samples (Figure S9, Table S4) and indicate the redistribution formation of a hydration layer at the PHI surface which of N-containing groups for the material prepared using KOH/ improves solubility.

Results

Conclusion