Development of new materials for photocatalysis is a challenge for scientists. Quantum chemical calculations (DFT in this case) can contribute in this activity by computing several optoelectronic properties with a high reliability. Furthermore, it is now possible to tackle the challenging simulation of electrochemical reactions happening at the surface of the (co)catalyst either in a simple (but fast) way using the Computational Hydrogen Electrode or using the more complex (but closer to experimental conditions) grand canonical DFT. In other words, it is now possible to use the quantum chemistry to understand finely the photocatalysis mechanism contributing to the design of new photocatalysts. The aim of this presentation is to illustrate some successes of the DFT modelling of photocatalysis. The lecture will be divided in two parts. In the first one, we will present the design of 2D-heterojunctions for photocatalysis. We will focus on the Mo-based chalcogenides (MoO3 and MoS2). Individually, these two materials don’t have an appropriate bandgap for photocatalysis. However, we showed by DFT calculations (HSE06 level) that the MoO3/MoS2 heterostructure can lead to band levels adapted for water spiltting. We analyzed the evolution of opto-electronic properties of various 2D MoO3-xSx/MoS2 heterostructures modified by chemical and physical approaches. While the MoO3/MoS2 heterostructure is a type III heterojunction having a metallic character, we find that a partial O substitution by S in MoO3 layer leads to a type-II heterostructure probably having a Z-scheme photocatalytic mechanism. In the last part, we will present the OER mechanism on CoOOH surface obtained by the grand canonical DFT. This mechanism will be compared to the one obtained by the CHE appraoch more frequently used by the community. The comparison between the two mechanisms highlights the strenghs and weaknesses of the CHE appraoch to treat electrochemical reactions.

Optimization and understanding of photoelectrocatalysis: What we can ask from DFT

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.