Spintronics seeks to functionalize antiferromagnetic materials to develop memory and logic devices operating at terahertz speed and robust against external magnetic field perturbations. To be useful, such functionality needs to be developed in thin film devices. The key functionality of long-distance spin-transport has, however, so far only been reported in bulk single crystal antiferromagnets, while in thin films, transport has so far been limited to a few nanometers. In this work, we electrically achieve a long-distance propagation of spin-information in thin films of the insulating antiferromagnet hematite. Through transport and magnetic imaging, we demonstrate a strong correlation between the efficiency of the transport of magnons, which carry spin-information, and the magnetic domain structure of the films. In thin films with large domains, magnons propagate over micrometer distances whilst they attenuate over much shorter distances in multidomain thin films. The governing factor of the attenuation is related to scattering at domain walls, and we demonstrate that we can reduce this through training by field

Photoelectrochemical water splitting uses solar power to decompose water to hydrogen and oxygen. Here we show how the photocatalytic activity of thylakoid membranes leads to overall water splitting in a bio-photo-electro-chemical (BPEC) cell via a simple process. Thylakoids extracted from spinach are introduced into a BPEC cell containing buffer solution with ferricyanide. Upon solar-simulated illumination, water oxidation takes place and electrons are shuttled by the ferri/ferrocyanide redox couple from the thylakoids to a transparent electrode serving as the anode, yielding a photocurrent density of 0.5 mA cm−2. Hydrogen evolution occurs at the cathode at a bias as low as 0.8 V. A tandem cell comprising the BPEC cell and a Si photovoltaic module achieves overall water splitting with solar to hydrogen efficiency of 0.3%. These results demonstrate the promise of combining natural photosynthetic membranes and man-made photovoltaic cells in order to convert solar power into hydrogen fuel.

Ti-doped, undoped, and Zn-doped hematite (-Fe2O3) thick (~1 m) films were found to be n-type, weak n-type, and p-type, respectively. Heterogeneous doping profiles were generated in 30 nm thick hematite stacks on F:SnO2 coated glass substrates with 25 nm thick SnO2 underlayers in order to investigate the effect of different doping profiles on photoelectrochemical performance and compare with homogenously-doped counterpart photoelectrodes. Among the homogenously-doped photoelectrodes, the Ti-doped sample displayed the highest plateau photocurrent but also the highest onset potential, whereas the Zn-doped one had the lowest onset potential and the lowest plateau photocurrent. Heterogeneouslydoped photoelectrodes displayed both high plateau photocurrent and low onset potential, with the highest performance achieved for the specimen with Ti-doped, undoped and Zn-doped layers at the bottom, center and top parts of the stack, respectively. This demonstrates the potential of heterogeneous doping to improve the performance of hematite photoelectrodes for solar water splitting. The most critical bottleneck towards the technological advancement of photoelectrochemical (PEC) cells for use in solar water splitting is the photoelectrode material, which must meet the requirements of being inexpensive, efficient, robust, and stable for water photoelectrolysis. One of the most promising materials for use as a photoanode for water splitting is hematite (-Fe2O3) due to its vast abundance, low cost, light absorption characteristics and stability in the conditions needed for water oxidation. 1 Indeed, a reported working stability of at least 1000 hours has very recently been reported. 2 But hematite photoanodes also display some prominent

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The orientation dependence on the photoelectrochemical properties of Sn-doped hematite photoanodes was studied by means of heteroepitaxial film growth. Nb-doped SnO2 (NTO) was first grown heteroepitaxially on c, a, r, and m plane single crystal sapphire substrates in three different orientations. Hematite was then grown in the (001), (110), and (100) orientations on the NTO films. The structural, morphological, optical, and photoelectrochemical properties of the photoelectrodes were studied. The hematite photoanodes possessed high crystallinity and smooth surfaces. Hole scavenger measurements made in H2O2-containing electrolyte revealed that the flux of photo-generated holes arriving at the surface was not significantly affected by orientation. Cathodic shifts in the onset potential for water photooxidation of up to 170 mV were observed for (110) and (100) oriented hematite photoanodes as compared to (001) oriented films. These results suggest that varying the orientation of heteroepitaxial thin film Sndoped hematite photoelectrodes primarily affects charge transfer into the electrolyte arising from the surface properties of the different crystal faces rather than affecting hole transport through the bulk under illumination. Electrochemical techniques were then used to probe the existence of surface states which were found to vary with both exposed crystal face as well as foreign dopant inclusion. Kelvin probe force microscopy (KPFM) measurements revealed correlation between the work function of the hematite films (measured in air) and the flat-band and onset potentials for water photo-oxidation (in alkaline aqueous solution).