A monolithically integrated device, protected by a TiO2 stabilization layer, splits water using sunlight.

Discovery of new materials drives the deployment of new technologies.Complex technological requirements demand precisely tailored material functionalities, and materials scientists are driven to search for these new materials in compositionally complex and often non-equilibrium spaces containing three, four or more elements. The phase behavior of these highorder composition spaces is mostly unknown and unexplored. High-throughput methods can offer strategies for efficiently searching complex and multidimensional material genomes for these much needed new materials and can also suggest a processing pathway for synthesizing them. However, highthroughput structural characterization is still relatively under-developed for rapid material discovery. Here, a synchrotron X-ray diffraction and fluorescence experiment for rapid measurement of both X-ray powder patterns and compositions for an array of samples in a material library is presented. The experiment is capable of measuring more than 5000 samples per day, as demonstrated by the acquisition of high-quality powder patterns in a bismuthvanadium-iron oxide composition library. A detailed discussion of the scattering geometry and its ability to be tailored for different material systems is provided, with specific attention given to the characterization of fiber textured thin films. The described prototype facility is capable of meeting the structural characterization needs for the first generation of high-throughput material genomic searches.

The solar-driven synthesis of fuel, which is performed by coupling the oxygen evolution reaction (OER) with fuel-forming hydrogen evolution or carbon dioxide reduction reactions, is a promising strategy for generating renewable energy.1 Chemical fuels offer high energy density and facile distribution, and photoelectrochemical (PEC) cells with tandem light absorbers and liquid-semiconductor junctions are being developed into efficient solar fuels generators. 2Widespread deployment of PEC solar fuels technology is impeded by several technological challenges, most notably the development of a stable photoanode that enables efficient photoelectrocatalysis of the OER. 2,3The coupling of solar light absorption with electrocatalysts enables efficient fuel generation but also poses substantial challenges with respect to the electrochemical stability of active components, particularly in the acidic or alkaline media that yield the highest device efficiencies. 4 A corresponding challenge for solar fuels research is the discovery of OER photoelectrocatalysts that exhibit stable operation in as high of a concentration of base as possible. Traditionally, with the notable exception of a-Fe 2 O 3 , the stability of low-band gap (below 2.5 eV) metal oxides has proved problematic. 5 In particular, compound metal oxide semiconductors such as bismuth vanadate (BiVO 4 ) suffer from rapid corrosion via anodic dissolution of V species. 6 In the present work we demonstrate that V corrosion is mitigated in copper vanadates through self-passivation. A primary strategy for protection of light absorbers in aqueous electrolytes is the application of an inert, protective coating, which often lowers efficiency due to increases in electrical resistance and recombination rates.