[en] Synthesizing 2D metal–organic frameworks (2D MOFs) in high yields and rational tailoring of the properties in a predictable manner for specific applications is extremely challenging. Now, a series of porphyrin-based 2D lanthanide MOFs (Ln-TCPP, Ln=Ce, Sm, Eu, Tb, Yb, TCPP=tetrakis(4-carboxyphenyl) porphyrin) with different thickness were successfully prepared in a household microwave oven. The as-prepared 2D Ln-TCPP nanosheets showed thickness-dependent photocatalytic performances towards photooxidation of 1,5-dihydroxynaphthalene (1,5-DHN) to synthesize juglone. Particularly, the Yb-TCPP displayed outstanding photodynamic activity to generate O${}_2$${}^{-<!--\; ???\; -->}$ and ${}^1$O${}_2$. This work not only provides fundamental insights into structure designing and property tailoring of 2D MOFs nanosheets, but also pave a new way to improve the photocatalytic performance. (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)