Warren, Scott C.Voitchovsky, KislonDotan, HenLeroy, Celine M.Cornuz, MaurinStellacci, FrancescoHebert, CecileRothschild, AvnerGraetzel, Michael2013-10-012013-10-012013-10-01201310.1038/Nmat3684https://infoscience.epfl.ch/handle/20.500.14299/95562WOS:000323417600022Charge transport in nanoparticle-based materials underlies many emerging energy-conversion technologies, yet assessing the impact of nanometre-scale structure on charge transport across micrometre-scale distances remains a challenge. Here we develop an approach for correlating the spatial distribution of crystalline and current-carrying domains in entire nanoparticle aggregates. We apply this approach to nanoparticle-based alpha-Fe2O3 electrodes that are of interest in solar-to-hydrogen energy conversion. In correlating structure and charge transport with nanometre resolution across micrometre-scale distances, we have identified the existence of champion nanoparticle aggregates that are most responsible for the high photoelectrochemical activity of the present electrodes. Indeed, when electrodes are fabricated with a high proportion of these champion nanostructures, the electrodes achieve the highest photocurrent of any metal oxide photoanode for photoelectrochemical water-splitting under 100 mW cm(-2) air mass 1.5 global sunlight.text::journal::journal article::research article