Photoelectrochemical properties of butane reduced flame‐treated Zr‐doped hematite thin films

Abstract

In this research, Zr‐doped hematite thin films were prepared by a simple and highly scalable liquid phase deposition method, and their photoelectrochemical (PEC) properties were investigated. The samples were post‐heat treated using a butane reduced flame. PEC studies revealed that both Zr‐doping and flame‐treatment enhanced the performance of the hematite photoanodes. The photocurrent densities of the samples were considerably increased upon flame‐treatment, that is, about 3.5 times for a 4% Zr‐doped sample. The highest photocurrent density at 1.23 V versus reversible hydrogen electrode (RHE) was obtained, about 0.50 mA cm−2 for the 4% Zr‐doped sample, about five times higher than the undoped sample. The Mott–Schottky measurements revealed that the donor charge carrier density for the 4% Zr‐doped sample was increased fivefold upon flame‐treatment from 2.49 × 1019 to 1.38 × 1020 cm−3. The optical investigations showed that the optical band gap energy values depend on the level of Zr‐doping, and the sample with 4% Zr‐doping showed the lowest band gap energy value, about 1.82 eV. The mechanism behind the effectiveness of the flame‐treatment was investigated and attributed to the oxygen vacancy formation upon flame‐treatment. The formation of oxygen vacancies activates the donor doping, and as a result, the charge carrier density increases. In general, butane reduced flame‐treatment as a simple and effective strategy can be used as a post‐heat treatment to boost the PEC properties of hematite thin films.

A facile route for decoration of hematite photoanodes by transition metal hydroxide co‐catalysts

“…6 Numerous research has been undertaken to improve the charge separation efficiency and OER kinetics of hematite. Various strategies, including element doping, [7][8][9] heterojunction, [10][11][12] and homojunction 13,14 construction, morphological manipulation, 15,16 post-annealing, 17 annealing at reducing atmosphere, 18,19 and co-catalyst loading, [20][21][22] have been investigated to enhance the photoelectrochemical characteristics of hematite.…”

Photoelectrochemical properties of single-grain hematite films grown by electric-field-assisted liquid phase deposition

“…For this purpose, iron ions (Fe 3+ ) can be substituted with ions with higher valence, such as Ti 4+ , 9 Nb 5+ , 10 and Zr 4+ . 11 Additionally, anion doping using fluorine has been performed to improve the PEC properties of hematite films by suppressing the recombination of generated electronhole pairs. 12,13 (2) Creating oxygen vacancies: introducing oxygen vacancies can increase the charge carrier density in the bulk material and on the semiconductor/electrolyte interface, which act as electroactive sites that enhance the kinetics of the OER.…”