Photoelectrochemical properties of texture‐controlled nanostructured α‐Fe₂O₃ thin films prepared by AACVD

Abstract

Nanostructured α-Fe2O3 thin film electrodes were deposited by aerosol assisted chemical vapour deposition (AACVD) for photoelectrochemical (PEC) water splitting on conducting glass substrates using 0.1M methanolic solution of Fe(acac)3. The XRD analysis confirmed that the films are highly crystalline α-Fe2O3 and free from other iron oxide phases. The highly reproducible electrodes have optical bandgap of ~2.15 eV and exhibit anodic photocurrent. The current-voltage characterization of the electrodes reveals that the photocurrent density strongly dependend on films morphology and deposition temperature. The SEM analysis showed a change in the surface morphology with the change in deposition temperature. The films deposited at 450 °C have nanoporous structures which provide maximum electrode/electrolyte interface. The maximum photocurrent density of 455 μA/cm 2 was acheived at 0.25V vs. Ag/AgCl/3M KCl (~ 1.23 V vs. RHE) and IPCE of 23.6% at 350 nm for the electrode deposited at 450 °C.

Nanostructured Fe2O3 Processing via Water‐Assisted ALD and Low‐Temperature CVD from a Versatile Iron Ketoiminate Precursor

“…The photocurrent onset was detected at 0.8 V versus RHE (Figure S14, Supporting Information), which is in agreement with typically reported values . The performance of the bare iron oxide is comparable to other reports on thin iron oxide films without doping or modification by co‐catalysts . It should be noted that more advanced nanostructuring methods of the photoanode material may result in higher current densities by overcoming the problems of short diffusion length of minority charge carriers (holes) .…”

Interplay of thickness and photoelectrochemical properties in nanostructured α-Fe2 O3 thin films

“…In particular, the lateral nano‐aggregate size should approach as close as possible the hole diffusion length in hematite systems. A reduced path length decreases the probability of electron–hole recombination in the inner material regions, improving thus the ultimate PEC performances . This is indeed the case of the systems obtained with a deposition time of 10 min in the present work.…”

“…Solar water splitting in PEC cells has emerged as a clean and cost‐effective method for the sustainable production of H 2 in view of different applications . Among the different metal oxides studied as photoanodes, hematite (α‐Fe 2 O 3 ) displays promising properties for PEC water oxidation .…”

“…In particular, it has been shown that holes generated outside the depletion region undergo recombination and do not contribute to water oxidation photocurrent. By adjusting film thickness and aggregate size to the same order of magnitude as the depletion layer, recombination phenomena can be restricted and photo‐produced electrons can efficiently reach the external circuit , resulting thus in improved performances.…”

Effect of Film Thickness on Photoelectrochemical Performance of SnO2 Prepared via AACVD

“…Photoelectrochemical (PEC) water splitting is one of the most promising approaches to store clean and abundant solar energy in form of hydrogen. This technology utilizes semiconducting materials such as BiVO 4 , Fe 2 O 3 , and WO 3 as photoanode to initiate the PEC process. The performance of semiconductor in this system depends strongly on the intrinsic properties of photoanode material as well as morphological properties of the thin film including surface roughness, structure (nanoparticles, nanorods, nanosheets, and so on), and film thickness.…”