Vacuum-annealing induces sub-surface redox-states in surfactant-structured α-Fe2O3 photoanodes prepared by ink-jet printing

Abstract

Transparent nano-structured hematite (α-Fe2O3) films of approximately 550 nm thickness on tin-doped indium oxide (ITO) have been obtained conveniently by ink-jet printing of a Fe(NO3)3 / Brij® O10 precursor ink and subsequent annealing at 500 °C in air. When illuminated with a blue LED ( = 455 nm, ca. 100 mW cm -2 ), the hematite films exhibited photocurrents of up to 70 A cm -2 at 0.4 V vs. SCE in 0.1 M NaOH electrolyte. Thermal annealing in vacuum at 500 °C for 2 h increased photocurrents more than three times to 230 A cm -2 in agreement with previous literature reports for pure hematite materials.These results suggest that a simple ink-jetting process with surfactants is viable. The effects of vacuum-annealing on the photoelectrical properties of α-Fe2O3 films are discussed in terms of a sub-surface state templating hypothesis based on data gathered from phototransients, field emission scanning electron microscopy, X-ray photoelectron spectroscopy analysis, X-ray diffraction, photocurrent spectra, and cyclic voltammetry.

Tin and Oxygen-Vacancy Co-doping into Hematite Photoanode for Improved Photoelectrochemical Performances

“…Then, it was found that it could be used as active site to improve the PEC performance. Oxygen vacancy appears in the special conditions like rapid thermal process (RTP) [28], which can bring about oxygen separation from the metaloxidation lattice [29]. Currently, oxygen vacancies are regarded as intrinsic defects and positive charges because of the strong electronegativity of oxygen.…”

Synthesis, characterization, physical and thermodynamic properties of a novel anionic surfactant derived fromSapindus laurifolius

“…Because of their behavioural characteristic of reducing surface tension at the water-air and oil-water interfaces, they are used widely in various industries as occulating and wetting agents, adhesives, inks, emulsiers and de-emulsiers and in the oil and gas industries. [1][2][3][4] However, most of the commercial synthetic surfactants have signicant detrimental effects on the environment, which has driven researchers to synthesize natural surfactants from renewable resources. [5][6][7] The focus on an eco-friendly environment concerns the use of surfactants and creates interest to develop a natural surfactant against commercial non-biodegradable surfactant.…”

Residual Energy Harvesting from Light Transients Using Hematite as an Intrinsic Photocapacitor in a Symmetrical Cell

“…The anodic spike arises from charge separation and rapid electron diffusion toward/into the FTO−hematite interface. 27,28 The fast decay following the anodic spike is usually associated with slow oxygen evolution kinetics and the presence of surface traps (pseudocapacitance). Trap concentrations can be enhanced due to defects on the surface or in the crystal structure often associated with a low degree of crystallinity and purity of the hematite film.…”