**1. Introduction**

Graphene, a monolayer of graphite, has attracted intense interest in recent years because of its unique two-dimensional structure and excellent physical and chemical properties such as high electronic and thermal conductivity, great mechanical strength, and huge specific surface area. [1-4] However, due to its zero bandgap semiconductor characteristic and a highly transparent property in the visible spectrum, pristine graphene is severely limited in optoelectronic and photo-energy conversion applications.

Photoactive graphene in recent years bring up impressive phenomena that remarkably sustain and expand the graphene research interests. The rise of photoactive graphene in photonics and optoelectronics is evidenced by a spate of latest reports, typically photovoltaics and photoca‐

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talysts. Although there is some available literature covering various aspects of photoactive graphene,[1, 5, 6] a strategic update that reflects the newest progress, growing trends, and opening opportunities of photoactive graphene is required. This chapter pays particular attention to the development of photoactive graphene, including material preparation, the photophysical progress of excited organic molecules and graphene, as well as its applications in optoelectronics and photocatalysis.
