Nanostructured alpha-Fe2O3 thin films for photoelectrochemical hydrogen generation

We acknowledge PMI2 connect program of the British Council for partly funding the present work

Nanostructured ZnO Thin Films for Optical, Electrical, and Photoelectrochemical Applications from a New Zn Complex

New hexanuclear zinc complex, Zn₆(OAc)₈(μ-O)₂(dmae)₄ (<b>1</b>) (OAc = acetato, dmae = <i>N,N</i>-dimethyl aminoethanolato) has been synthesized and characterized by its melting point, elemental analysis, Fourier transform infrared spectroscopy, atmospheric-pressure chemical-ionization mass spectrometry, thermal gravimetric analysis, and single crystal X-ray analysis. The complex (<b>1</b>) crystallizes in the monoclinic space group <i>C</i>2/<i>c</i>. The high solubility of complex (<b>1</b>) in organic solvents such as alcohol, THF, and toluene and low decomposition temperature as compared to Zn­(OAc)₂ make it a promising single source candidate for the deposition of nanostructured ZnO thin films by aerosol-assisted chemical vapor deposition. Films with various nanostructures, morphology, and crystallographic orientation have been deposited by controlling the deposition temperature. The deposited films have been characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. The optical characterization of ZnO films deposited on the FTO substrate show a direct band gap of 3.31 eV, and the photoelectrochemical study revealed that the photocurrent onset is at about −0.32 V, whereas no photocurrent saturation was observed. The <i>I</i>–<i>V</i> measurements designated the deposited films as ohmic semiconductors

Photoelectrochemical and photoresponsive properties of Bi2S3 nanotube and nanoparticle thin films

Bi2S3 nanotubes and nanoparticle in the form of thin films were deposited on fluorine doped SnO2 (FTO) coated conducting glass substrates by Aerosol Assisted Chemical Vapor Deposition (AACVD) using tris-(N,N-diethyldithiocarbamato)bismuth(III), [Bi(S2CN(C2H5)2)3]2 (1) as a precursor. Thin films were deposited from solutions of (1) in either chloroform, dichloromethane, or a 1:1 mixture of chloroform and toluene at temperature between 350 to 450 °C and characterized by X-ray diffraction (XRD), UV−vis spectroscopy, field emission gun scanning electron microscopy (FEGSEM), and energy dispersive X-ray (EDX) analysis. FEGSEM images of films deposited from chloroform or dichloromethane exhibit well-defined and evenly distributed nanotubes with an average internal diameter of 40 nm. Films deposited from chloroform/toluene, on the other hand, have compact nanostuctured morphology. Bandgaps of 1.85 and 1.8 eV were estimated for nanotubes and nanoparticles, respectively, by extrapolating the linear part of the Tauc plot recorded for the films. The n-type Bi2S3 thin films display a reasonable photoactivity under illumination and are thus promising candidates for photoelectrochemical applications. The photoelectrochemical characteristics recorded under AM 1.5 illumination indicated photocurrent density of 1.9 mA/cm2 and 1.0 mA/cm2 at 0.23 V versus Ag/AgCl/3 M KCl for the films deposited from chloroform and chloroform/toluene, respectively. The photocurrent is among the highest reported for any Bi2S3 photoelectrode to date. Repeated illumination cycles show that the Bi2S3 thin films display a reasonable photosensitivity and response indicating their potential to be used in photodetector and optoelectronic nanodevice applications

New insights into water splitting at mesoporous alpha-Fe2O3 films: a study by modulated transmittance and impedance spectroscopies

Thin mesoporous films of α-Fe2O3 have been prepared on conducting glass substrates using layer-by-layer self-assembly of ca. 4 nm hydrous oxide nanoparticles followed by calcining. The electrodes were used to study the oxygen evolution reaction (OER) in the dark and under illumination using in situ potential-modulated absorption spectroscopy (PMAS) and light-modulated absorption spectroscopy (LMAS) combined with impedance spectroscopy. Formation of surface-bound higher-valent iron species (or “surface trapped holes”) was deduced from the PMAS spectra measured in the OER onset region. Similar LMAS spectra were obtained at more negative potentials in the onset region of photoelectrochemical OER, indicating involvement of the same intermediates. The impedance response of the mesoporous α-Fe2O3 electrodes exhibits characteristic transmission line behavior that is attributed to slow hopping of holes, probably between surface iron species. Frequency-resolved PMAS and LMAS measurements revealed slow relaxation behavior that can be related to the impedance response and that indicates that the lifetime of the intermediates (or trapped holes) involved in the OER is remarkably long

Nanostructured ZnO Thin Films for Optical, Electrical, and Photoelectrochemical Applications from a New Zn Complex

New hexanuclear zinc complex, Zn₆(OAc)₈(μ-O)₂(dmae)₄ (<b>1</b>) (OAc = acetato, dmae = <i>N,N</i>-dimethyl aminoethanolato) has been synthesized and characterized by its melting point, elemental analysis, Fourier transform infrared spectroscopy, atmospheric-pressure chemical-ionization mass spectrometry, thermal gravimetric analysis, and single crystal X-ray analysis. The complex (<b>1</b>) crystallizes in the monoclinic space group <i>C</i>2/<i>c</i>. The high solubility of complex (<b>1</b>) in organic solvents such as alcohol, THF, and toluene and low decomposition temperature as compared to Zn­(OAc)₂ make it a promising single source candidate for the deposition of nanostructured ZnO thin films by aerosol-assisted chemical vapor deposition. Films with various nanostructures, morphology, and crystallographic orientation have been deposited by controlling the deposition temperature. The deposited films have been characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. The optical characterization of ZnO films deposited on the FTO substrate show a direct band gap of 3.31 eV, and the photoelectrochemical study revealed that the photocurrent onset is at about −0.32 V, whereas no photocurrent saturation was observed. The <i>I</i>–<i>V</i> measurements designated the deposited films as ohmic semiconductors

New Insights into Water Splitting at Mesoporous α-Fe₂O₃ Films: A Study by Modulated Transmittance and Impedance Spectroscopies

Thin mesoporous films of α-Fe₂O₃ have been prepared on conducting glass substrates using layer-by-layer self-assembly of ca. 4 nm hydrous oxide nanoparticles followed by calcining. The electrodes were used to study the oxygen evolution reaction (OER) in the dark and under illumination using in situ potential-modulated absorption spectroscopy (PMAS) and light-modulated absorption spectroscopy (LMAS) combined with impedance spectroscopy. Formation of surface-bound higher-valent iron species (or “surface trapped holes”) was deduced from the PMAS spectra measured in the OER onset region. Similar LMAS spectra were obtained at more negative potentials in the onset region of photoelectrochemical OER, indicating involvement of the same intermediates. The impedance response of the mesoporous α-Fe₂O₃ electrodes exhibits characteristic transmission line behavior that is attributed to slow hopping of holes, probably between surface iron species. Frequency-resolved PMAS and LMAS measurements revealed slow relaxation behavior that can be related to the impedance response and that indicates that the lifetime of the intermediates (or trapped holes) involved in the OER is remarkably long

Silver(I) complexes of 9-anthracenecarboxylic acid and imidazoles: synthesis, structure and antimicrobial activity

[Ag2(9-aca)2] (1) (9-acaH = 9-anthracenecarboxylic acid) reacts with a series of imidazoles to give [Ag(imidH)2.3(CH3CN)0.7](9-aca) (3), [Ag6(imidH)4(9-aca)6(MeOH)2] (4), {[Ag(1-Me-imid)2]2[Ag4(9- aca)6]} (5), {[Ag(1-Bu-imid)2]2[Ag4(9-aca)6]} (6) and [Ag(apim)](9-aca)·H2O (7) (imidH = imidazole; 1-Me-imid = 1-methylimidazole; 1-Bu-imid = 1-butylimidazole; apim = 1-(3-aminopropyl)imidazole). The mononuclear complex 3, hexanuclear 4–6, and polymeric 7, were all characterised using X-ray crystallography. While many of the complexes possess excellent in vitro antifungal and antibacterial activities they are, unanimously, more effective against fungal cells. The insect, Galleria mellonella, can survive high doses of the Ag(I) complexes administered in vivo, and a number of the complexes offer significant protection to larvae infected with a lethal dose of pathogenic Candida albicans cells