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Paper   IPM / Physic / 14662
School of Physics
  Title:   Optimization of charge transport in a Co-Pi modified hematite thin film produced by a scalable electron beam evaporation for photoelectrochemical water oxidation
  Author(s): 
1.  B. Eftekharinia
2.  A. Moshaii
3.  A. Dabirian
4.  N. Sobhkhiz
  Status:   Published
  Journal: J. Mater. Chem. A
  Vol.:  5
  Year:  2017
  Pages:   3412-3424
  Supported by:  IPM
  Abstract:
Hematite (α-Fe2O3) is an attractive candidate for photoelectrochemical (PEC) hydrogen generation by water splitting due to its low cost, earth-abundance and appropriate bandgap. However, large scale production of hematite thin films with efficient PEC performance is a challenging problem in the field. In this article, based on an electron beam evaporation method, we provide a scalable route for preparation of a Co-Pi modified hematite thin film with efficient solar water splitting properties. To our knowledge, no work has been done on photo-electrochemistry characterization of Co-Pi modified hematite films prepared based on electron beam evaporation. We show that by optimization of deposition conditions including film thickness and annealing temperature and performing the deposition in an oxygen medium, an efficient PEC performance is achieved from the produced pristine hematite photoanode. By various characterizations including XRD, EDX, SEM, transient photocurrent and I-V measurements, and impedance spectroscopy, it is shown that the efficient performance is attributed to improving crystalline structure and suppression of recombination centre originated from the defects in bulk and surface of the hematite layer. Also with deposition of different thicknesses of Co-Pi electrocatalyst on the hematite layer, the optimum structure for fast water oxidation and charge transfer kinetics across the interface of photoanode and electrolyte is obtained. The most efficient photoanode delivers up to 1.5 (mA/cm2) at the potential of 1.5 V versus reversible hydrogen electrode (RHE), which is among the large value photocurrents attained from a hematite-based photoanode, but with the advantage of large scale production capability of the proposed method of this work.

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