Chloride Ion-Induced Spatial Separation and Long Recombination Time of Photogenerated Electrons and Holes in Crystalline Carbon Nitride
Xu Cai, Wei Lin
Abstract
High Resolution Image Download MS PowerPoint Slide Poly(triazine imide)·Li + Cl – (PTI/Li + Cl – ) as one of the most reported crystalline carbon nitrides has shown exciting potential for photocatalysis. However, understanding the role of Li + /Cl – in the photoexcited charge transfer in the time and space of PTI is a challenging problem. Here, we have investigated the nonradiative charge recombination of series ion intercalated PTI systems (PTI/Li + X –, where X = F, Cl, Br, and I) by performing the ab initio nonadiabatic molecular dynamics simulations. The results indicate that the intercalated anions in PTI/Li + Cl – and PTI/Li + Br – have the potential to trap holes, separate the electrons and holes, and prolong the nonradiative electron–hole recombination. In particular, ∼70% of holes in PTI/Li + Cl – can transport among interlayers toward the {0001} planes, while most of the electrons are transferred to the {101̅0} planes, exhibiting different transport pathways and directions. Furthermore, PTI/Li + Cl – has an electron–hole recombination time as long as 136 ns, which explains its excellent optoelectronic properties. This work provides a theoretical baseline for the reported facet engineering improvement of crystalline carbon nitride for overall water splitting.