Exploiting clean energy is essential for sustainable development and sunlight‐driven photocatalytic water splitting represents one of the most promising approaches toward this goal. Metal‐organic frameworks (MOFs) are competent photocatalysts owing to their tailorable functionality, well‐defined structure, and high porosity. Yet, the introduction of the unambiguous metal‐centered active site into MOFs is still challenging since framework motifs capable of anchoring metal ions firmly are lacking. Herein, the assembly using 1,4‐dicarboxylbenzene‐2,3‐dithiol (H2dcbdt) and Zr‐Oxo clusters to give a thiol‐functionalized UiO‐66 type framework, UiO‐66‐dcbdt, is reported. The thiocatechols on the struts are allowed to capture transition metal (TM) ions to generate UiO‐66‐dcbdt‐M (M  = Fe, Ni, Cu) with unambiguous metal‐thiocatecholate moieties for photocatalytic hydrogen evolution reaction (HER). UiO‐66‐dcbdt‐Cu is found the best catalyst exhibiting an HER rate of 4.18 mmol g−1 h−1 upon irradiation with photosensitizing Ru‐polypyridyl complex. To skip the use of the external sensitizer, UiO‐66‐dcbdt‐Cu is heterojunctioned with titanium dioxide (TiO2) and achieves an HER rate of 12.63 mmol g−1 h−1 (32.3 times that of primitive TiO2). This work represents the first example of MOF assembly employing H2dcbdt as the mere linker followed by chelation with TM ions and undoubtedly fuels the rational design of MOF photocatalysts bearing well‐defined active sites.

Compared to monometallic counterparts, bimetallic two‐dimensional conjugated metal‐organic framework (2D c‐MOF) nanosheets possess preferable metal tunability and synergistic effect for performance optimization, yet rarely developed in photocatalytic hydrogen evolution to date. In this study, a feasible post‐synthetic strategy of second metal installation (SMI) is proposed and applied to construct a crystalline bimetallic 2D c‐MOF nanosheet, HTHATN‐Ni‐Pt‐NS. HTHATN‐Ni‐Pt‐NS exhibits high electrical conductivity and efficient hydrogen evolution with the rate of 47.2 mmol g−1 h−1, which is 13.5‐fold higher than that of pristine HTHATN‐Ni‐NS without PtII decoration under visible light irradiation. Experimental and theoretical analysis reveal that introduction of low amount of PtII provides catalytically active metal sites and optimizes the ΔGH* value of NiII centers, thus resulting in the enhanced performance of proton reduction. This study represents the first example of symbiotic bimetallic centers in MOF nanosheets highlighting SMI strategy as an efficient approach to construct photocatalysts.

Using sunlight to manufacture hydrogen offers promising access to renewable clean energy. For this, low‐cost photocatalyst with effective light absorption and charge transfer are crucial, as current top‐performing systems often involve precious metals like Pd and Pt. An integrated organic–inorganic photocatalyst based on the cheap metals of iron and nickel are reported, wherein the metal ions form strong metal‐sulfur bonds with the organic linker molecules (2,5‐dimercapto‐1,4‐benzenedicarboxylic acid, H4DMBD) to generate 2D coordination sheets for promoting light absorption and charge transport. The 2D sheets are further modified through ionic metal‐carboxylate moieties to allow for functional flexibility. Thus, high‐surface‐area thin nanosheets of this 2D material, with an optimized Fe/Ni ratio (0.25:1.75), and in heterojunction with CdS nanosheet, achieve a stable photocatalytic hydrogen evolution rate of 12.15 µmol mg−1 h−1. This work synergizes coordination network design and nano‐assembly as a versatile platform for catalyzing hydrogen production and other sustainable processes.