A Titanium‐Doped SiO_x Passivation Layer for Greatly Enhanced Performance of a Hematite‐Based Photoelectrochemical System

Abstract

This study introduces an in situ fabrication of nanoporous hematite with aT i-doped SiO x passivation layer for ah igh-performance water-splitting system. The nanoporous hematite with aT i-doped SiO x layer (Ti-(SiO x /np-Fe 2 O 3 )) has ap hotocurrent density of 2.44 mA cm À2 at 1.23 V RHE and 3.70 mA cm À2 at 1.50 V RHE .W hen ac obalt phosphate co-catalyst was applied to Ti-(SiO x /np-Fe 2 O 3 ), the photocurrent density reached 3.19 mA cm À2 at 1.23 V RHE with stability,which shows great potential of the use of the Ti-doped SiO x layer with as ynergistic effect of decreased charge recombination, the increased number of active sites,a nd the reduced hole-diffusion pathwayf rom the hematite to the electrolyte.

Quasi-Topotactic Transformation of FeOOH Nanorods to Robust Fe2O3 Porous Nanopillars Triggered with a Facile Rapid Dehydration Strategy for Efficient Photoelectrochemical Water Splitting

“…20−23 Most recently, a silica encapsulation method was introduced to retain the Fe 2 O 3 nanowire morphology even after high-temperature calcination at 800 °C. 24,25 In addition, the FeOOH nanorod precursor covered by a ZrO 2 shell can also withstand high-temperature structural collapse and produce robust Fe 2 O 3 nanotubes through analogous Kirkendall effect. 26 In this work, a facile rapid dehydration (RD) strategy is explored for quasi-topotactic transformation of FeOOH nanorods to robust Fe 2 O 3 porous nanopillars.…”

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

“…[1a,b] In particular,h ematite (a-Fe 2 O 3 )h as been extensively investigated as ac andidate for PEC water oxidation and ap otential photoanode for PEC carbon dioxide (CO 2 ) reduction owing to its photostability,s uitable band gap (ca. [5a,b,c] Extensive investigations have been done to promote the PEC activity of hematite,a nd many efforts have focused on the reduction of bulk or surface recombination (e.g., by nanostructuring, [6a-c] element doping, [7] and electrocatalyst deposition). [2] However,poor conductivity,rapid electron-hole recombination, [3] short hole diffusion lengths (2-4 nm), [4] and sluggish oxygen-evolution kinetics have greatly limited its practical application.…”

“…[2] However,poor conductivity,rapid electron-hole recombination, [3] short hole diffusion lengths (2-4 nm), [4] and sluggish oxygen-evolution kinetics have greatly limited its practical application. [5a,b,c] Extensive investigations have been done to promote the PEC activity of hematite,a nd many efforts have focused on the reduction of bulk or surface recombination (e.g., by nanostructuring, [6a-c] element doping, [7] and electrocatalyst deposition). [8a-c] However,e ven though the suppression of substrate/hematite interfacial recombination is of equal importance,t his topic has been much less intensively investigated.…”

Improving Photocatalytic Performance Using Nanopillars and Micropillars

“…Ahn et al investigated the applicability of the hematite iron oxide species in water splitting performance by synthesizing a hematite and Ti-doped SiOx passivation layer structure (Ti-SiOx/np-Fe2O3) to be compared to a simple Ti-Fe2O3 sample. The thin passivation layer of Ti-doped of amorphous SiOx was synthesized in situ by hydrothermal/annealing processes to induce nanopores and increase photoelectrochemical performance [12]. The surface area of the Ti-(SiOx/np-Fe2O3) sample increased by 2.5 times com- Ahn et al investigated the applicability of the hematite iron oxide species in water splitting performance by synthesizing a hematite and Ti-doped SiO x passivation layer struc-ture (Ti-SiO x /np-Fe 2 O 3 ) to be compared to a simple Ti-Fe 2 O 3 sample.…”

“…The surface area of the Ti-(SiOx/np-Fe2O3) sample increased by 2.5 times com- Ahn et al investigated the applicability of the hematite iron oxide species in water splitting performance by synthesizing a hematite and Ti-doped SiO x passivation layer struc-ture (Ti-SiO x /np-Fe 2 O 3 ) to be compared to a simple Ti-Fe 2 O 3 sample. The thin passivation layer of Ti-doped of amorphous SiO x was synthesized in situ by hydrothermal/annealing processes to induce nanopores and increase photoelectrochemical performance [12]. The surface area of the Ti-(SiO x /np-Fe 2 O 3 ) sample increased by 2.5 times compared to the simple Ti-Fe 2 O 3 sample.…”