Morphology and Light‐Dependent Spatial Distribution of Spin Defects in Carbon Nitride

Abstract

Carbon nitride (CN) is a heterogeneous photocatalyst that combines good structural properties and a broad scope. The photocatalytic efficiency of CN is associated with the presence of defective and radical species. An accurate description of defective states—both at a local and extended level—is key to develop a thorough mechanistic understanding of the photophysics of CN. In turn, this will maximise the generation and usage of photogenerated charge carriers and minimise wasteful charge recombination. Here the influence of morphology and light‐excitation on the number and chemical nature of radical defects is assessed. By exploiting the magnetic dipole‐dipole coupling, the spatial distribution of native radicals in CN is derived with high precision. From the analysis an average distance in the range 1.99–2.34 nm is determined, which corresponds to pairs of radicals located approximately four tri‐s‐triazine units apart.

Novel Asymmetric Aggregation Strategy to Boost Charge Separation in Carbon Nitride Polymers for High-Performance Hydrogen Photosynthesis

“…It is widely accepted that triplet states have a long lifetime. 56,57 Thus, we can safely believe that the CT and triplet states together promote the separation and transfer of charge carriers in the aggregates. 58 The above results reveal that the SS-CNP aggregates have efficient separation and transfer of charge carriers.…”

Z-Scheme Heterojunction α-Fe2O3/Tubular g-C3N4 with C Defects for Photocatalytic Degradation of Microcystin-LR in Water: Generation and Effect of Critical Species 1O2

“…The results showed that all samples display a Lorentzian signal centrosymmetric at g = 2.0042, attributed to the local unpaired electrons belonging to sp 2 hybridized C atom in the p orbital. 36 The EPR signal, on the one hand, represented the generation of amorphous carbon nitride, 37 while on the other hand, it was used as evidence for the formation of vacancies. 38 The signal values of DCN and TDCN were sequentially enhanced compared to g-C 3 N 4 , which implied that the same type of defects was present in both samples.…”

Nitrogen‐Based Imperfections in Graphitic Carbon Nitride – New Trend for Enhancing Photocatalytic Activity?

“…For a more in-depth understanding of the measurements conducted with EPR and related techniques, we recommend consulting the following articles. [113,114] Moreover, the re-organization of the heptazine motifs might cause not only the distortion in π-π conjugation but also new appearing polar functional groups. For this purpose, Fourier transform infrared spectroscopy (FTIR) plays a crucial role since different reagents and conditions might lead to distinct defects whether cyano, amino or other types.…”

“…Nevertheless, certain pioneering studies employing pulsed dipolar and hyperfine spectroscopies have unveiled the precise positioning of two radical pairs, approximately 2 nm apart (equivalent to roughly four tri‐s‐triazine moieties). For a more in‐depth understanding of the measurements conducted with EPR and related techniques, we recommend consulting the following articles [113,114] …”