1 Basic Principles of Photocatalysis<br>2 The Role of Layer Structure in Photocatalysis<br>3 Applications of Layered Photocatalysts<br>4 Layered Bismuth-Based Photocatalysts 1: BiOX (X=Cl, Br, I)<br>5 Layered Bismuth-Based Photocatalysts 2: BiXO4(X=V, P)<br>6 Layered Bismuth-Based Photocatalysts 3: Bi2XO6 (X= Mo, W)<br>7 Metal-Free Layered Photocatalysts 1: g-C3N4<br>8 Metal-Free Layered Photocatalysts 2: Covalent Organic Framework<br>9 Layered Double Hydroxides Photocatalysts<br>10 Layer-Structured Co-Catalyst for Photocatalysis 1: Graphene<br>11 Layer-Structured Co-Catalyst for Photocatalysis 2: Transition Metal Sulfide<br>12 Layer-Structured Co-Catalyst for Photocatalysis 3: MXene<br>13 Face-to-Face 2D/2D Heterojunction between Layered Photocatalysts<br>