Photocatalytic water oxidation with iron oxide hydroxide (rust) nanoparticles

Shelton, Timothy L.; Bensema, Bronwyn L.; Brune, Nicholas K.; Wong, Christopher J.; Yeh, Max; Osterloh, Frank E.

doi:10.1117/1.jpe.7.012002

Cited by 1 publication

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the surface electronic properties of iron oxyhydroxide polymorphs differ qualitatively, 22,23 the 2.15 eV bandgap energy of 5−15 nm β-FeOOH NCs 14 is close to that of the herein reported complexes of γ-FeOOH NCs (see below), and both are similar to the 2.0 eV bandgap of hematite NCs. 24 Moreover, computational data from a recent study carried out using hybrid DFT functionals show a striking similarity between the polaronic structures of excited-state hematite and γ-FeOOH.…”

Section: ■ Introductionmentioning

confidence: 95%

“…Based on those findings, and using our recently developed deployment of polyoxometalate (POM) cluster anions as ligands for metal-oxide NCs 24,26,27 to build on the work of Osterloh et al, 14 we now report a macroanion-like POM complex of 2.6 nm γ-FeOOH NCs, 1, that not only catalyzes visible light-driven water oxidation with no need for added photosensitizers but also whose unique stability and solubility facilitate detailed kinetic and mechanistic investigation of electron scavenger-promoted oxygen evolution using the toolbox of solution-state methods typically reserved for molecular catalysis.…”

Section: ■ Introductionmentioning

confidence: 99%

“…It is now well established that mixed-metal oxyhydroxides of Fe and first-row transition metals such as Mn, Cr, Co, and Ni are dramatically more rapid and efficient electrocatalysts for water oxidation than any of the single-metal materials alone. − Moreover, detailed investigations identify Fe(III) as the active site at which O–O bond formation occurs. ,− Despite this intriguing and potentially important role of Fe, less is known about the catalytic properties of the iron oxyhydroxides, FeOOH, themselves. ,,− …”

Section: Introductionmentioning

confidence: 99%

“…Unlike hematite, however, much less is known regarding their photocatalytic properties and catalytic activities. One notable exception is Osterloh’s demonstration that in combination with NaIO 4 , dispersed 5–15 nm β-FeOOH NCs (Figure b) catalyze water oxidation upon irradiation with visible light in the absence of added photosensitizers. Despite eventual aggregation of the β-FeOOH NCs, the system was sufficiently stable to establish that rates of O 2 production increased with pH and with an increase in catalyst concentration.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Solution-State Catalysis of Visible Light-Driven Water Oxidation by Macroanion-Like Inorganic Complexes of γ-FeOOH Nanocrystals

et al. 2021

View full text Add to dashboard Cite

Recent investigations reveal that by providing active sites for O−O bond formation, Fe(III) oxyhydroxides (FeOOH) dramatically enhance the oxygen evolution activities of iron-containing abundant-earth CoO x H y and NiO x H y electrocatalysts. In contrast to α-Fe 2 O 3 (hematite), however, little detailed information is available concerning fundamental reactivities of the Fe(III) oxyhydroxides themselves. We here report a macroanion-like polyoxometalate cluster-anion complex of 2.6 nm γ-FeOOH nanocrystals, 1, that not only catalyzes visible light-driven water oxidation with no need for added photosensitizers but also whose unique stability and solubility facilitate investigation of oxygen evolution using the toolbox of solution-state methods typically reserved for molecular catalysis. The γ-FeOOH active centers of 1 are comprised of ca. 250 Fe atoms and coordinated by an average of six oxo-donor ligands, [α-PW 11 O 39 Fe III ] 4− -μ-O − , each with a formal charge of 5−, giving freely diffusing macroanion-like hexacoordinate complexes readily observed in their native, vitreous water solution state by cryogenic TEM. With a bandgap energy of 2.3 eV and valence-and conduction-band (VB and CB) energies of 2.34 and 0.04 V vs NHE, 1 catalyzes visible light-driven water oxidation by orthoperiodate {H 3 I VII O 6 } 2− at pH 8, at a rate similar to that documented for hematite nanocrystals. Kinetic data show the reaction to be one-half order in concentrations of both 1 and {H 3 I VII O 6 } 2− , indicative of a chain mechanism. A solvent kinetic isotope effect (KIE), k H /k D , of 1.32 was assigned to the rate-limiting trapping of photoexcited electrons by {H 3 I VII O 6 } 2− , which initiates a radical-chain process inhibited by added iodate [I V O 3 ] − . In contrast to the rate-determining O−O bond formation typical of metal-oxide electrocatalysts and of many molecular catalysts, chain mechanisms initiated by the rate-limiting trapping of excited-state electrons may prove a general feature of water oxidation by freely diffusing photoactive nanocrystals.

show abstract