# van der Waals heterostructure for photocatalysis: Graphitic carbon nitride and Janus transition-metal dichalcogenides

## TL;DR

This study explores a van der Waals heterostructure combining Janus transition-metal dichalcogenides and graphitic carbon nitride, revealing promising electronic, optical, and excitonic properties for efficient solar-driven water splitting.

## Contribution

It introduces a novel heterostructure design and first-principles analysis demonstrating enhanced photocatalytic features for renewable energy applications.

## Key findings

- Effective charge separation due to internal electric field.
- Broad optical absorption in visible and UV spectrum.
- Lower exciton binding energy indicating efficient charge separation.

## Abstract

Converting solar energy into chemical energy by splitting water is a promising means to generate a sustainable and renewable solution without detrimental environmental impact. The two-dimensional semiconductors serve as potential catalysts in this regard, and here we combine Janus transition-metal dichalcogenides (MoXY, X/Y = S, Se, Te) and graphitic carbon nitride in a van der Waals heterostructure. Within the first-principles calculations, we investigate the electronic, optical and excitonic properties that determine the photocatalytic activity. Due to the internal electric field, the photogenerated electrons and holes are separated in the MoXY layers, and also generates high overpotentials for the redox reactions. The high optical absorptions span throughout the entire visible and near ultraviolet regime in these heterostructure nanocomposites. Further, the lower exciton binding, calculated within the two-dimensional hydrogenic model, indicates efficient charge separation. Enormous tunability of photocatalytic properties in such heterostructures should attract considerable theoretical and experimental attention in future.