Au-Cu_2O COMPOSITES PHOTOCATALYSTS: LOCALIZED SURFACE PLASMON RESONANCE VS. SCHOTTKY JUNCTION

摘要

Photocatalysis and photovoltaics as an alternative green energy have made great progress in the past decade by virtue of the advancement of advanced materials. However, the low charge-separation efficiency of photogenerated electron/hole pairs and poor visible-light absorption still severely constrain their further development especially toward commercial production. In view of these scientific problems, strategies such as adopting surface plasmon resonance (SPR) enhancements, building up multijunctions at nanoscale, developing new materials/systems, etc., have been keenly developed. Among those, plasmonic photocatalysts have emerged as a new kind of photocatalysts because of the enhancement effect mediated by propagating SPR or localized SPR (LSPR). Herein, we initiate a strategy to distinguishing and tuning the LSPR and Schottky effects using a simple composite photocatalyst Au/Cu_2O. In this paper, we have designed a simple method for identifying the LSPR and Schottky effects. Insulating self assembled monolayers (SAMs) between Au nanocrystals and cuprous oxide were introduced. Cysteine (cys) and mercaptoundecanoic acid (MUA) SAMs as linkers with different chain lengths were used respectively for making Au-cys-Cu_2O and Au-MUA-Cu_2O cubic composites. Both visible-light (λ ＞ 420nm) and UV-light (ca. λ = 254 nm) sources were applied to differentiate the two effects, i.e., the LSPR and Schottky effects.