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

Abstract

A facile rapid dehydration (RD) strategy is explored for quasi-topotactic transformation of FeOOH nanorods to robust FeO porous nanopillars, avoiding collapse, shrink, and coalescence, and compared with a conventional treatment route. Additionally, the so-called RD process is capable of generating a beneficial porous structure for photoelectrochemical water oxidation. The obtained RD-FeO photoanode exhibits a photocurrent density as high as 2.0 mA cm at 1.23 V versus reversible hydrogen electrode (RHE) and a saturated photocurrent density of 3.5 mA cm at 1.71 V versus RHE without any cocatalysts, which is about 270% improved photocurrent density over FeO with the conventional temperature-rising route (0.75 mA cm at 1.23 V vs RHE and 1.48 mA cm at 1.71 V vs RHE, respectively). The enhanced photocurrent on RD-FeO is attributed to a synergistic effect of the following factors: (i) preservation of single crystalline nanopillars decreases the charge-carrier recombination; (ii) formation of long nanopillars enhances light harvesting; and (iii) the porous structure shortens the hole transport distance from the bulk material to the electrode-electrolyte interface.

Porous Single‐Crystal‐Based Inorganic Semiconductor Photocatalysts for Energy Production and Environmental Remediation: Preparation, Modification, and Applications

“…In this way, the methods can be grouped according to the reaction type as solvothermal (hydrothermal),2,16,17 sol–gel synthesis,18 chemical vapor deposition (CVD),19 molten‐salt reaction,20,21 electrochemical22 and ion‐exchange methods 23,24. Moreover, based on the strategy to generate porosity, preparation procedures for PSCs can also be divided into hard‐templating,2,7,16,17,23,25–27 soft‐templating,28–35 and template‐free 22,36–41. For the purpose of this review, PSCs preparation procedures have been classified according to the manner employed to create porosity, so that the amazing range and variety of PSCs can be remarked.…”

“…Inset of panel I is the corresponding SAED pattern. Reproduced with permission 37. Copyright 2017, American Chemical Society.…”

“…Using a different dehydration strategy, porous hematite nanopillars on FTO substrate have been synthesized from FeOOH nanorods 37. In this route, the FeOOH was directly placed into a 250 °C furnace to induce fast dehydration, instead of the conventional slow temperature‐rising process, followed by a two‐step high temperature annealing.…”

In Situ Decorating Coordinatively Unsaturated Fe Sites for Boosting Water Oxidation Performance of TiO2 Photoanode

“…As shown in Figure b, FeOOH/TiO 2 and MIL‐100(Fe)/TiO 2 both display the relatively stable and renewable photocurrent density during several cycles with alternating light and dark. It is worth noting that the photocurrent of FeOOH/TiO 2 exhibits an obvious decay trend compared with the bare TiO 2 because FeOOH is not very stable and tends to turn into other iron oxide . The introduction of the crystal structure of MIL‐100 could effectively anchor Fe 3+ ions inside a more fixed chemical environment by carboxyl coordination, which makes its photocurrent become more stable during the light on–off process.…”

Urchin-like NiCoP coated with a carbon layer as a high-performance electrode for all-solid-state asymmetric supercapacitors

“…The increasing pores could be ascribed to the decomposition of precursors to release small molecules during the carbonization and phosphorization processes. 30,31 The pores are favorable for improving the performance of energy storage and catalysis. 32 The TEM images of NiCoP@C-ULAs and its representative area are shown in Fig.…”