title: Computational screening for effective Ge1-xSix nanowire photocatalyst.
abstract: We perform a comprehensive mapping of GeSi nanowire (NW) electronic band characteristics versus the alloy composition and the diameter (up to 3 nm) using hybrid density functional theory (DFT) calculations, the cluster expansion method and Monte Carlo simulations. We reveal that stable alloy GeSi NW configurations across compositions tend to exhibit asymmetric core-shell structures, which enhance spatial separation of the band edges, making them more effective for electron-hole charge separation as compared to conventional symmetric core-shell structures. More importantly, from the composition-size map of the NW band edges, we show that GeSi NWs with diameters below 3 nm are thermodynamically capable of photocatalysing water-splitting reactions (alkaline conditions) and CO2 reduction. In particular, NWs with diameters of 2 and 3 nm possess desirable properties for efficient photo-conversion; their bandgaps (1.4 to 2.0 eV) match well with the solar spectrum.
authors.affiliation: Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore. tantl@ihpc.a-star.edu.sg ngmf@ihpc.a-star.edu.sg.
authors.forename: Teck L
authors.initials: TL
authors.lastname: Tan
authors.forename: Man-Fai
authors.initials: MF
authors.lastname: Ng