Fe(P)(NO), where P = TPP, TPC, or OEP, is reduced in three one-electron steps in nonaqueous solvents. The products of the first two waves (Fe(P)(NO)" and Fe(P)(NO)2") were stable, and the visible spectra were obtained by using OTTLE spectroelectrochemistry. The vibrational spectra of Fe(P)(NO) and its first reduction product obtained coulometrically were recorded. The porphyrin vibrations for both species were consistent with low-spin ferrous complexes. The vno and vfc-n bands could also be observed for both complexes, though i>n0 for Fe(TPP)(NO)" was quite weak. For Fe(TPP)(NO), vN0 (15N values in parentheses) was 1681 cm"1 (1647 cm"1) and vFe_N was 525 cm"1 (517 cm"1). Upon reduction, vN0 decreased to 1496 cm"1 (1475 cm"1) while vFe-N increased to 549 cm"1 (538 cm"1). These results were consistent with the addition of the electron to the half-filled d,2 + orbital, which is formed from * 0 and iron dz2 orbitals. Therefore, addition of an electron to this orbital would lead to a strengthening of the Fe-N bond and a weakening of the N-O bond. Dc polarography of Fe(TPP)(NO) and Fe(TPC)(NO) was carried out in the presence of several substituted phenols. The limiting current and half-wave potential of the first wave were unaffected by the presence of the phenols, except at high phenol concentrations. A new second wave appeared, though, in the presence of phenols, and the limiting current and half-wave potential for this wave depended strongly on the concentration and identity of the weak acid. The overall reduction appeared to involve three electrons on the polarographic time scale, to yield Fe(P)" and hydroxylamine. Further reduction to ammonia was observed on the coulometric time scale. Exhaustive electrolysis gave ammonia in nearly quantitative yield for 2-chlorophenol concentrations greater than 20 mM. No differences were observed in the polarographic behavior of Fe(TPP)(NO) and Fe(TPC)(NO), but somewhat higher concentrations of 2-chlorophenol were needed to generate ammonia coulometrically.

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Polymer solar cells (PSCs) are fabricated using a novel fi lm deposition method, the electrostatic spray (e-spray) technique. Stable atomization and uniform deposition of the polymer blend by e-spray are achieved by manipulating the solution concentration, the solvent composition, and the electric fi eld. The performance of PSCs is primarily infl uenced by the inherent fi lm morphology of the e-sprayed polymer-blend active layers, which is significantly different from that of the conventional fi lms that are formed using the spin-coating (SC) method. The intrinsically formed interfacial boundaries between the e-sprayed blend pancakes resist charge transport, which unfavorably infl uences device effi ciency. The internal series resistance ( R S ) of the PSCs that are formed using the e-spray method (e-spray-PSC) is signifi cantly reduced by a solvent vapor soaking (SVS) treatment in addition to the conventional thermodynamic nanomorphology controls. The detailed relationship between the morphologies (fi lm morphology and internal nanomorphology) and the R S is revealed using impedance spectroscopy. The performance of the e-spray-PSCs is comparable to those of the PSCs that are fabricated using the SC method under identical conditions. Therefore, the e-spray method can be used to fabricate ultralow-cost PSCs, because of the performance results combined with the intrinsic advantages that the e-spray method is simple and has a low materials loss.

The mechanistic aspects of a two-step method for the electrodeposition of a BiVO4 semiconductor (previously developed in the Rajeshwar/Tacconi laboratory) were elaborated by the combined application of voltammetry and EQCM. The electrosynthesized films were also characterized ex situ using SEM, EDX, XRD, and XPS. Stripping of pre-electrodeposited bismuth films, followed by reaction either with VO4 3− (formed by hydrolysis from the initially added VO3 − species) or with hydroxide ions, produced BiVO4 or Bi2O3 thin films in situ on the Pt electrode. The deposition potential, pH of the electrolyte, and choice of vanadium precursor were shown to be crucial variables in the composition of the electrodeposited film. When a more positive potential than 0.5 V (vs Ag/AgCl reference) was applied to the Bi-modified electrode in VO3 −-containing electrolyte, the content of Bi2O3 in the film increased instead of BiVO4. Stripping efficiency of the predeposited bismuth layer was increased at acidic electrolytes and resulted in higher BiVO4 content in electrodeposited films, whereas hydrolytic conversion of VO3 − to VO4 3− was promoted in basic electrolytes. Formation of Bi2O3 was also favored by the use of alkaline electrolytes (e.g., pH 10) for the electrodeposition. Photoelectrochemical experiments showed the electrosynthesized BiVO4 to be an n-type semiconductor, and reproducible photocurrents were obtained using a Na2SO4 supporting electrolyte.

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