Wednesday, 04 March, 2015

Electronically coupled hybrid structures by graphene oxide directed self-assembly of Cu2-xS nanocrystals

I. Kondofersky, H.K. Dunn, A. Muller, B. Mandlmeier, J.M. Feckl, D. Fattakhova-Rohlfing, C. Scheu, L.M. Peter, T. Bein -
ACS APPLIED MATERIALS & INTERFACES, DOI:10.1021/am5078667 (2015)

Nanostructuring has proven to be a successful strategy in overcoming the trade-off between light absorption and hole transport to the solid/electrolyte interface in hematite photoanodes for water splitting. The suggestion that poor electron (majority carrier) collection hinders the performance of nanostructured hematite electrodes has led to the emergence of host–guest architectures in which the absorber layer is deposited onto a transparent high-surface-area electron collector. To date, however, state of the art nanostructured hematite electrodes still outperform their host–guest counterparts, and a quantitative evaluation of the benefits of the host–guest architecture is still lacking. In this paper, we examine the impact of host–guest architectures by comparing nanostructured tin-doped hematite electrodes with hematite nanoparticle layers coated onto two types of conducting macroporous SnO₂ scaffolds. Analysis of the external quantum efficiency spectra for substrate (SI) and electrolyte side (EI) illumination reveals that the electron diffusion length in the host–guest electrodes based on an undoped SnO₂ scaffold is increased substantially relative to the nanostructured hematite electrode without a supporting scaffold. Nevertheless, electron collection is still incomplete for EI illumination. By contrast, an electron collection efficiency of 100% is achieved by fabricating the scaffold using antimony-doped SnO₂, showing that the scaffold conductivity is crucial for the device performance.

Article on journal's website