Photocatalysis Goes Thinner Than a Hair: Carbon Nitride Thin Films as All-in-one Technology for Photocatalysis

Abstract

Organic π-conjugated polymers are promising heterogeneous photocatalysts that involve photoredox or energy transfer processes. In such settings, the materials are usually applied in the form of a dispersion in liquid medium, which is bound to certain technological limits of applicability. Herein, we present an innovative approach using carbon nitride thin films prepared via chemical vapor deposition (CVD) at different vessel walls and using them as batch and microfluidic photoreactors. This approach allows not only to fabricate technologically relevant and reusable devices, also photophysical properties of carbon nitride, such as singlet-triplet energy gap and lifetime of triplet excited states, are improved, when the material is assembled in thin films. These morphological changes are employed to maximize performance of the materials in photocatalytic reactions, in which the carbon nitride thin films show at least one orders of magnitude higher activity per area unit compared to photocatalysis using suspended particles.<br>

A Tour‐Guide through Carbon Nitride‐Land: Structure‐ and Dimensionality‐Dependent Properties for Photo(Electro)Chemical Energy Conversion and Storage

“…[75] To date, the majority of experiments determine the electronic structure of carbon nitrides using optical spectroscopy performed on polycrystalline powder, though efforts have been made to prepare highly crystalline thin films for spectroscopic investigations. [33,76] Characterization based on powder may lead to conflicting results if sample quality is not carefully controlled. As a case in point, the UV-vis spectrum of melon shows an absorption onset at around 450 nm (2.8 eV transition) and, depending on how the sample had been prepared, a tail near the absorption onset may be visible at higher wavelengths.…”