Improved Photocatalytic Performance of TiO-Nitrogen-Doped Graphene Quantum Dot Composites Mediated by Heterogeneous Interactions.

Photocatalysis is typically monitored via analysis of phases in isolation and focuses on the removal of a target analyte from the solution phase. Here we analyze the photocatalytic action of a TiO-nitrogen-doped graphene quantum dot (NGQD) composite on a target analyte, phenol, using comprehensive multiphase NMR (CMP-NMR) which observes signals in solid, solution, and gel phases . Phenol preferentially interacts with the composite photocatalyst compared to pure TiO, increasing its effective concentration near the catalyst surface and its degradation rate.

TiO-NGQD composite photocatalysts with switchable photocurrent response.

A series of titanium dioxide-nitrogen doped graphene quantum dot (TiO-NGQD) composite photocatalysts were synthesized through a simple hydrothermal reaction with varied NGQD content. Through a proposed Z-Scheme heterojunction, the composites were able to achieve increased photocurrent generation and photocatalytic degradation of phenol under both full spectrum and visible only illumination. The prepared composites were able to switch from anodic to cathodic photocurrent by changing the light source from full spectrum to visible wavelengths.

A new perspective on the photocatalytic action of titanium dioxide on phenol elucidated using comprehensive multiphase NMR.

Comprehensive Multiphase NMR (CMP-NMR) is a recently developed technique capable of simultaneously observing different phases - solutions, gels, and solids - while providing the chemical specificity of traditional NMR. With this new tool, the heterogeneous photocatalysis of phenol by titanium dioxide (P25 TiO) is re-examined to gain information about the occurrence of reaction at different regions between the catalyst and the solution. It was found that the proportion of phenol in different phases changes over the course of the photodegradation period.