In this study, a highly efficient photocatalytic H2 production system is developed by employing porphyrins as photocatalysts. Palladium and platinum tetracarboxyporphyrins (PdTCP and PtTCP) are adsorbed or coadsorbed onto TiO2 nanoparticles (NPs), which act as the electron transport medium and as a scaffold that promotes the self‐organization of the porphyrinoids. The self‐organization of PdTCP and PtTCP, forming H‐ and J‐aggregates, respectively, is the key element for H2 evolution, as in the absence of TiO2 NPs no catalytic activity is detected. Notably, J‐aggregated PtTCPs are more efficient for H2 production than H‐aggregated PdTCPs. In this approach, a single porphyrin, which self‐organizes onto TiO2 NPs, acts as the light harvester and simultaneously as the catalyst, whereas TiO2 serves as the electron transport medium. Importantly, the concurrent adsorption of PdTCP and PtTCP onto TiO2 NPs results in the most efficient catalytic system, giving a turnover number of 22,733 and 30.2 mmol(H2) g(cat)−1.

Here, the ability of a novel near‐infrared dye to noncovalently self‐assemble onto the surface of single‐walled carbon nanotubes (SWCNTs) driven by charge‐transfer interactions is demonstrated. Steady‐state, Raman, and transient absorption spectroscopies corroborate the electron donating character of the near‐infrared dye when combined with SWCNTs, in the form of fluorescence quenching of the excited state of the dye, n‐doping of SWCNTs, and reversible charge transfer, respectively. Formation of the one‐electron oxidized dye as a result of interactions with SWCNTs is supported by spectroelectrochemical measurements. The ultrafast electronic process in the near‐infrared dye, once immobilized onto SWCNTs, starts with the formation of excited states, which decay to the ground state via the intermediate population of a fully charge‐separated state, with characteristic time constants for the charge separation of 1.5 ps and charge recombination of 25 ps, as derived from the multiwavelength global analysis. Of great relevance is the fact that charge‐transfer occurs from the hot excited state of the near‐infrared dye to SWCNTs.

In the scientific race to build up photoactive electron donor-acceptor systems with increasing efficiencies,l ittle is knowna bout the interplay of their building blocks when integrated into supramolecular nanoscale arrays,p articularly in aqueous environments.Here,wedescribe an aqueous donoracceptor ensemble whose emergence as an anoscale material renders it remarkably stable and efficient. We have focused on at etracationic zinc phthalocyanine (ZnPc) featuring pyrenes, which shows an unprecedented mode of aggregation, driven by subtle cooperation between electrostatic and p-p interactions. Our studies demonstrate monocrystalline growth in solution and as ymmetry-breaking intermolecular charge transfer between adjacent ZnPcs upon photoexcitation. Immobilizing an egatively charged fullerene (C 60)a se lectron acceptor onto the monocrystalline ZnPc assemblies was found to enhance the overall stability,a nd to suppress the energy-wasting charge recombination found in the absence of C 60 .O verall, the resulting artificial photosynthetic model system exhibits ahigh degree of preorganization, which facilitates efficient charge separation and subsequent charge transport.

The investigation of molecular model systems is fundamental towards a deeper understanding of key photochemical steps in natural photosynthesis. In here, we report an entirely non-covalent triad consisting of boron...

Im Zuge der Entwicklung von effizienteren, lichtaktiven Elektronen-Donor-Akzeptor-Systemen ist wenig darüber bekannt, wie einzelneB austeine in einem supramolekularen, Nanometer großen Gerüst miteinander wechselwirken, besonders in wässrigen Umgebungen. In dieser Arbeit beschreiben wir ein wässriges Elektronen-Donor-Akzeptor-System, dessen Struktur im Nanobereiche ine herausragende Stabilitätu nd Effizienz aufweist. Unser Fokus lag auf einem tetrakationischen Zink(II)phthalocyanin (ZnPc) mit Pyren-Gruppen, das eine beispiellose Form der Aggregation aufgrund einer subtilen Kooperation von elektrostatischen und pp Wechselwirkungen aufweist. Unsere Untersuchungen zeigen ein monokristallines Wachstum in Lçsung und einen lichtinduzierten, symmetriebrechenden intermolekularen Elektronen-Transfer zwischen benachbarten ZnPcs.N ach Zugabe von einem negativ geladenen Fulleren (C 60)als Elektronenakzeptor konnte neben einer verbesserten Stabilitäta uchd ie energieverschwendende Ladungsrekombinationu nterdrückt werden, die in Abwesenheit von C 60 stattfand. Im Ganzen betrachtet bietet dieses photosynthetische Modellsystem einen hohen Grad an Vororganisation, welched ie effiziente Ladungstrennung und den anschließenden Ladungstransport begünstigt.