Photocatalytic conversion of CO₂ into energy-rich chemicals by two-dimensional nanomaterials

In recent years two-dimensional (2D) nanomaterials have remained unique photocatalysts owing to the associated superior physical, chemical, and mechanical properties. These include larger surface-volume ratio, abundant surface defects, transparency, suitable atomic thickness, the higher ratio of uncoordinated surface atoms, numerous active sites, short transport distance in the bulk phases, stronger quantum electron confinements in the 2D, numerous rich options of host-guest species, environmentally friendly, economical, abundant in nature, and ultrathin characteristics. Also, 2D-nanomaterials offer practical ways of promoting light absorption and separation and a promising approach to transferring the photogenerated charge carriers. However, since the advent of monolayered graphene-based nanomaterials, graphitic carbon nitride-based nanomaterials, metal chalcogenide-based nanomaterials, metal oxide-based nanomaterials, and metal oxyhalide-based nanomaterials, numerous novel 2D-nanomaterials were developed for CO₂ photoreduction to energy-rich chemicals, thus the study of different 2D-photocatalysts remains the hottest topics to date. In this chapter, different 2D-nanomaterials are reviewed, the fundamental aspect of photocatalytic CO₂ reduction (CO₂R), and steps of the photocatalytic conversion of CO₂ with water on a typical semiconductor photocatalyst are also discussed. In conclusion, some shortcomings and prospects for enhancing the performance of 2D-nanomaterials and the CO₂ photoreduction are suggested to advance the field to meet reliable industrial applications.