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In this paper, we investigate the tunability of Se reduction products (Se0(s)vs.H2Se(g)) during the photocatalytic reduction of selenate over TiO2, using formic acid as an electron hole scavenger, in synthetic mine-impacted brines (SMIB). Photocatalytic reduction can effectively remove Se from SMIB to <2 μg L−1from an initial Se concentration of >3300 μg L−1in under 10 × 1019photons cm−2. An increase in solution temperature led to a marked increase in selenate removal kinetics and an increase in selectivity towards H2Se(g), while increasing the concentration of formic acid led to an increase in selenate removal kinetics and a decrease in the selectivity towards H2Se(g). A bivariate response surface analysis was used to elucidate the mechanism behind the production of >99% gaseous H2Se or >85% solid Se0, under varying reaction conditions. Finally, a two-pronged electron transfer model is proposed to explain the selectivity towards Se0(s)vs.H2Se(g)under varying conditions: (i) Se0(s)is produced through direct reduction of selenate by TiO2conduction band electrons and (ii) H2Se gas is produced through electrons transferred into Se0, followed by an autocatalytic reduction of Se0to H2Se or through a direct reduction by CO2−.

To determine the ability of semiconductors templated by α-helical polypeptides to form higher order structures and the charge carrier properties of the supramolecular assemblies, l-lysine was functionalized with a sexithiophene organic semiconductor unit via iterative Suzuki coupling and the click reaction. The resultant amino acid was incorporated into a homopolypeptide by ring-opening polymerization of an amino acid N-carboxyanhydride. Spectroscopic investigation of the polypeptide revealed that it adopted an α-helical secondary structure in organic solvents that underwent hierarchical self-assembly to form higher order structures. In cyclohexane, the polymer formed organogels at 2% (w/v). Organic photovoltaic and organic field effect transistor devices were fabricated by deposition of the PCBM blended active layer from chlorobenzene at concentrations shown to induce self-assembly of the polymer. Compared with control compounds, these devices showed significantly greater hole mobility, short circuit current, and efficiency. This work establishes the potential of this previously unreported bioinspired motif to increase device performance.