The sandwich-type polyoxometalate (POM) [(PWO)Co(HO)] was immobilized in the hexagonal channels of the Zr(IV) porphyrinic MOF-545 hybrid framework. The resulting composite was fully characterized by a panel of physicochemical techniques. Calculations allowed identifying the localization of the POM in the vicinity of the Zr clusters and porphyrin linkers constituting the MOF. The material exhibits a high photocatalytic activity and good stability for visible-light-driven water oxidation. It thus represents a rare example of an all-in-one fully noble metal-free supramolecular heterogeneous photocatalytic system, with the catalyst and the photosensitizer within the same porous solid material.

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Inspired by the metal active sites of formate dehydrogenase and CO-dehydrogenase, a nickel complex containing a NiS 4 motif with two dithiolene ligands mimicking molybdopterin has been prepared and structurally characterized. During electroreduction, it converts to a good catalyst for the reduction of CO 2 into formate as the major product, together with minor amounts of carbon monoxide and hydrogen, with reasonable overpotential requirement, good faradaic yield, and notable stability. Catalysis operates on a mercury electrode and dramatically less on a carbon electrode, as observed in the case of [Ni(cyclam)] 2+ complexes. Density functional theory (DFT) computations indicate the key role of a Ni(III)-hydride intermediate and provide insights into the different reaction pathways leading to HCOOH, CO, and H 2 . This study opens the route toward a new, yet unexplored, class of mononuclear sulfur-coordinated Ni catalysts for CO 2 reduction.

We investigate the electrochemical properties of CVD grown graphene towards the detection of various biologically prevalent analytes including l-ascorbic acid (AA), dopamine hydrochloride (DA), β-nicotinamide adenine dinucleotide (NADH), uric acid (UA) and epinephrine (EP). We find that the observed electrochemical response of the CVD-graphene towards these select analytes does not originate from the graphene, however, from various other contributions including the presence of 'graphitic islands' on the surface of the CVD-graphene which dominate its electrochemistry. In the systems studied within, it appears at best, CVD-graphene acts akin to that of an edge plane pyrolytic graphite (EPPG) electrode constructed from highly ordered pyrolytic graphite. However, in other cases, the response of the CVD-graphene is worse than that of an EPPG electrode, which is likely due to the low O/C ratio.

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A molybdenum-dithiolene-oxo complex was prepared as a model of some active sites of Mo/W-dependent enzymes. The ligand, a quinoxaline-pyran-fused dithiolene, mimics molybdopterin present in these active sites. For the first time, this type of complex was shown to be active as a catalyst for the photoreduction of protons with excellent turnover numbers (500) and good stability in aqueous/organic media and for the electroreduction of protons in acetonitrile with remarkable rate constants (1030 s(-1) at -1.3 V versus Ag/AgCl). DFT calculations provided insight into the catalytic cycle of the reaction, suggesting that the oxo ligand plays a key role in proton exchange. These results provide a basis to optimize this new class of H2 -evolving catalysts.

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We have critically compared graphene and graphene oxide as materials for utilisation as supercapacitors indicating that the former exhibits a larger capacitance over the latter which has implications for those fabricating supercapacitors.