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Hematite (α-Fe2O3) has emerged as a promising material for photoelectrochemical (PEC) water splitting thanks to its abundance, stability in an aqueous environment, favorable optical bandgap and position of the electronic valence band. Nevertheless, its performance as a photoanode is considerably lower than what is theoretically achievable. In particular, the high electrochemical potential usually needed to initiate water oxidation is detrimental to the prospect of using hematite for practical devices. In this review we elucidate the appealing, as well as the challenging, aspects of using hematite for PEC water splitting and focus on the recent efforts towards lowering the onset potential of water oxidation. We examine and rationalize several strategies pursued to achieve this goal involving manipulation of the hematite/electrolyte interface, as well as improving relevant properties of hematite itself. [ABSTRACT FROM AUTHOR]

Functionalization of transition metal oxides using metallic nanoparticles is an interesting route towards efficient photoelectrochemical hydrogen production via water splitting. Although an enhanced photocurrent in photoanodes upon functionalization with metallic nanostructures has been observed in several studies, to the best of our knowledge no measurements of the Faradaic efficiency (FE) of the oxygen evolution reaction (OER) have been reported for such systems. This work characterizes the FE on a model system consisting of ultra-thin films of hematite (Fe2O3) sensitized with Ti/Au nanodisks. Compared to bare hematite references, sensitized samples showed significantly enhanced photocurrents as well as O2 evolution. Experimental evidence suggests that the observed enhancement was not due to photocatalytic activity of the nanodisks. The FE has been determined to be 100%, within the experimental errors, for both sensitized and reference samples. Also, this work demonstrates that the sensitized samples were stable for at least 16 hours photocurrent testing. The concepts shown in this work are generally applicable to any situation in which a semiconductor has its water splitting performance enhanced by metallic nanostructures. [ABSTRACT FROM AUTHOR]

A novel device for nanometer-confinement of soft matter in one dimension (1D) is presented. This nanocell, with very large (up to 106:1) cell-radius to cell-height ratio, is tailored as an accessory for quartz crystal microbalance (QCM) and QCM with dissipation-monitoring (QCM-D) sensing to study internal and interfacial energy dissipation phenomena in highly confined (in 1D) soft matter and fluid films (patent pending). The cell consists of two macroscopic plates (diameter of 9 mm), a top (the “lid”) and a bottom (the QCM-D sensor), separated by appropriate spacers with heights ranging from below 100 nm up to 10 μm. The surfaces of both the lid and the bottom plate can be mechanically or/and chemically modified, prior to cell assembly, in order to tailor desired interfacial properties for the experiment. The cell is mounted on a standard QCM-D sensor, an AT-cut quartz crystal (the quartz crystal is cut at an angle of 35° from its ZX-plane), forming the bottom plate. We illustrate theoretically and experimentally, as application examples, the use of this device for studies of dynamic mass loading and internal energy dissipation processes in thin films of ethylene glycol respective thin liquid crystal films around the nematic-isotropic phase transition. [ABSTRACT FROM AUTHOR]