Photocatalytic overall water splitting holds great promise for sustainable hydrogen production. For overall water splitting performed by one-step excitation, both the hydrogen evolution and oxygen evolution reactions are hindered kinetically; hence, it is necessary to employ site-selective modification of photocatalysts with hydrogen-evolving and oxygen-evolving cocatalysts. However, critical challenges remain, including the need for cumbersome, multi-step photodeposition processes and durable blocking layers to inhibit the reverse reactions. Here we find a conductive, two-dimensional metal–organic framework to serve as a simple, multifunctional cocatalyst. We loaded this framework on SrTiO₃:Al, an overall water-splitting photocatalyst, using a one-step self-assembly method. The framework cocatalyst promoted steady photocatalysis with an apparent quantum efficiency of 31.5% at 350 nm, free from the reverse reaction even without blocking layers. We proposed the operational principles for the cocatalyst activity using spectroscopic, electrochemical and theoretical analyses. This two-dimensional metal–organic framework offers an all-in-one approach for designing efficient and practical one-step excitation overall water-splitting systems. The alternative text for this image may have been generated using AI.

Development of efficient electrocatalysts for hydrogen evolution reactions (HERs) is necessary to achieve environmentally friendly and sustainable hydrogen production. To reduce cost and to circumvent the scarcity of platinum, the most efficient catalyst for HER, it is essential to develop catalysts using ubiquitous base metals or minimal amounts of precious metals. Bis(diimino)metal (MDI) coordination nanosheets are potential HER catalysts because their electric conductivities, two‐dimensionality, and porous structures provide large surface areas and efficient mass and electron transfer. In addition, with sparse metal arrangements in their chemical structures, nanosheets can reduce the amount of metal needed. We synthesized bis(diimino)palladium coordination nanosheets (PdDI) as a coordination polymer composed of bis(diimino)palladium, with semiconducting characteristics, using gas‐liquid interfacial synthesis and electrochemical oxidation. These electrochemically synthesized PdDIs exhibit remarkable catalytic performance with overpotential reaching 10 mA cm ⁻² of 34 mV, a Tafel slope of 47 mV dec ⁻¹ , and an exchange current density of 2.1 mA cm ⁻² after appropriate activation. This performance is closely comparable to that of metallic platinum. An ex‐situ investigation of the activation process revealed that reduction of the divalent Pd center in bis(diimino)palladium produced a composite of Pd(0) species and PdDI, combining high catalytic activity with smooth electron transfer.

We developed an efficient and convenient electrochemical method to synthesize π-conjugated redox metal-complex linear polymer wires composed of azobenzene-bridged bis(terpyridine)metal (2-M, M = Fe, Ru) units covalently immobilized on glassy carbon (GC). Polymerization proceeds by electrochemical oxidation of bis(4′-(4-anilino)-2,2′:6′,2″-terpyridine)metal (1-M) in a water–acetonitrile–HClO₄ solution, affording ultralong wires up to 7400 mers (corresponding to ca. 15 μm). Both 2-Fe and 2-Ru undergo reversible redox reactions, and their redox behaviors indicate remarkably fast redox conduction. Anisotropic hetero-metal-complex polymer wires with Fe and Ru centers are constructed via stepwise electropolymerization. The cyclic voltammograms of two hetero-metal-complex polymer wires, GC/[2-Fe]–[2-Ru] (3) and GC/[2-Ru]–[2-Fe] (4), show irreversible redox reactions with opposite electron transfer characteristics, indicating redox diodelike behavior. In short, the present electrochemical method is useful to synthesize polymer wire arrays and to integrate functional molecules on carbon.

We report a novel functional bis(terpyridine)metal(II) complex coordination nanosheet (CONASH) comprising a three-armed terpyridine ligand and Ni²⁺ ion. The colourless Ni-terpyridine CONASH was synthesized by the method of interfacial coordination reaction at an interface of two immiscible liquids. The synthesized CONASH was characterized with various microscopic observations such as TEM, SEM, and AFM, and spectroscopic measurements such as XPS, IR, SEM/EDS, and UV–Vis spectroscopy. The bis(terpyridine)nickel(II) complex nanosheet demonstrated redox-activity stemming from terpyridine complexes without distinctive colour change. Thus, the bis(terpyridine)nickel(II) coordination nanosheet is a potential redox-active material with colourlessness and flexibility, necessary for future transparent electronics.

Heterostructures of two‐dimensional materials realise novel and enhanced physical phenomena, making them attractive research targets. Compared to inorganic materials, coordination nanosheets have virtually infinite combinations, leading to tunability of physical properties and are promising candidates for heterostructure fabrication. Although stacking of coordination materials into vertical heterostructures is widely reported, reports of lateral coordination material heterostructures are few. Here we show the successful fabrication of a seamless lateral heterojunction showing diode behaviour, by sequential and spatially limited immersion of a new metalladithiolene coordination nanosheet, Zn₃BHT, into aqueous Cu(II) and Fe(II) solutions. Upon immersion, the Zn centres in insulating Zn₃BHT are replaced by Cu or Fe ions, resulting in conductivity. The transmetallation is spatially confined, occurring only within the immersed area. We anticipate that our results will be a starting point towards exploring transmetallation of various two‐dimensional materials to produce lateral heterojunctions, by providing a new and facile synthetic route.