Dendritic Hematite Nanoarray Photoanode Modified with a Conformal Titanium Dioxide Interlayer for Effective Charge Collection

Abstract

This paper describes the introduction of at hin titanium dioxide interlayer that serves as passivation layer and dopant source for hematite (a-Fe 2 O 3 )nanoarrayphotoanodes. This interlayer is demonstrated to boost the photocurrent by suppressing the substrate/hematite interfacial charge recombination, and to increase the electrical conductivity by enabling Ti 4+ incorporation. The dendritic nanostructure of this photoanode with an increased solid-liquid junction area further improves the surface charge collection efficiency,g enerating ap hotocurrent of about 2.5 mA cm À2 at 1.23 Vv ersus the reversible hydrogen electrode (vs.R HE) under air mass 1.5G illumination. Aphotocurrent of approximately 3.1 mA cm À2 at 1.23 Vvs. RHE could be achieved by addition of an iron oxide hydroxide cocatalyst.

A novel CoOOH/(Ti, C)-Fe2O3 nanorod photoanode for photoelectrochemical water splitting

“…As shown in Fig. S4, the absorption edges of the as-synthesized photoanodes are in the range of 590 to 600 nm, respectively, and the band-gap energies of the samples are 1.9 to 2.0 eV, respectively, which are consistent with recent reports [20,22,23]. (Fig.…”

“…Among them, n depends on the characteristics of the optical transition in a semiconductor, i.e., direct transition (n = 1) or indirect transition (n = 4) [23]. Fe 2 O 3 pertains to indirect transition and the value of n is 4.…”

“…The J max of α-Fe 2 O 3 is more than 12 mA cm -2 , but the reported water oxidation photocurrent densities of α-Fe 2 O 3 are within the range of 1-5 mA cm −2 [20,23], due to the poor electrical conductivity [3,16,24], which results in inefficient migration rate and poor separation of photo-generated electrons and holes [25], resulting in solar energy degradation [22,23]. We believe that future enhancement of the PEC performance of α-Fe 2 O 3 photoanode will focus on improving the electrical conductivity of α-Fe 2 O 3 .…”

“…On the other hand, when the photo-generated electrons and holes are separated from the inside of α-Fe 2 O 3 , the photo-generated electrons will move to the cathode of PEC cell for hydrogen evolution reaction (HER) and the photo-generated hole will move to the surface of photoanode for oxygen evolution reaction (OER) [1,23]. However, the PEC water splitting performance of α-Fe 2 O 3 is limited because a majority of the holes are recombined when migrating to surface, leading to the poor catalytic activity of the α-Fe 2 O 3 surface for oxygen evolution [24].…”

Current progress in developing metal oxide nanoarrays-based photoanodes for photoelectrochemical water splitting

“…The key of the method is to construct the precursor arrays. The subsequent metal oxide arrays can be obtained by heat treatment or other treatment [153,154].…”