Photocatalysts for the decarboxylation conversion of C(sp³)-carboxylic acids: a review

C(sp³)-carboxylic acids are derived from a broad spectrum of sources and possess excellent biosafety. Its decarboxylation conversion provides an important route for constructing C-H, C[double bond, length as m-dash]C and C-X (X = C, O, and F) bonds. Photocatalysis provides a mild and efficient method for achieving this conversion. In this paper, the photocatalysts used in the decarboxylation of C(sp³)-carboxylic acids over the past 8 years are systematically reviewed. They are classified into four categories: organic transition metal complexes, simple transition metal salts, metal-free homogeneous photocatalysts and semiconductor material photocatalysts. The structural characteristics, catalytic principles and reaction mechanisms of various catalysts are described in detail, and the core reaction paths of different catalytic systems are analyzed. The advantages and disadvantages of various catalysts in terms of catalytic efficiency, substrate applicability, cost and recovery were compared. Finally, the key challenges in this field are pointed out, and the future development directions, such as the design of near-infrared light-responsive catalysts and the improvement of quantum efficiency, are proposed.