# Light‐Induced On‐Surface Reactions: Bridging Photochemistry and Surface Science

## TL;DR

This paper reviews how light-induced reactions on surfaces can create carbon-based nanomaterials, focusing on how traditional photochemistry and surface science principles interact.

## Contribution

The paper bridges traditional photochemistry with surface science to better understand on-surface photoreactions.

## Key findings

- Light-induced reactions on nonmetallic surfaces offer a new route for nanomaterial synthesis.
- Molecular preorganization significantly influences the outcome of on-surface photoreactions.
- Ultra-high vacuum conditions are critical for studying photoexcitation mechanisms on surfaces.

## Abstract

Molecular on‐surface photochemistry recently emerged as an alternative strategy to thermal reactions to synthesize low‐dimensional carbon‐based nanomaterials, particularly on nonmetallic surfaces. However, there is still limited knowledge about the crucial aspects influencing photoreactivity in the context of surface chemistry, which contrasts with the fast progress in thermally activated reactions on metal surfaces. By reviewing recent developments in the on‐surface photochemistry field, this minireview focuses on some key aspects crucial for the comprehension of photoreactions on surfaces: from the photoexcitation process to basic mechanistic aspects and intermediates characterization, including the molecular preorganization impact on the reaction evolution. To clarify these aspects, we rely upon well‐established concepts of traditional photochemistry while highlighting the role of the surface. Finally, it is concluded with considerations on the evolution of the field.

This minireview examines molecular on‐surface photochemistry as an emerging strategy for synthesizing carbon‐based nanomaterials on substrates. A special emphasis is placed on bridging traditional photochemistry principles with surface science concepts. We discuss photoexcitation mechanisms under ultra‐high vacuum conditions, reaction pathways following light activation, and the critical role of molecular preorganization in determining reaction outcomes.© 2025 WILEY‐VCH GmbH