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Co/Ni-polyoxotungstate photocatalysts as precursor materials for electrocatalytic water oxidation


Güttinger, Robin; Wiprächtiger, Giann; Blacque, Olivier; Patzke, Greta R (2021). Co/Ni-polyoxotungstate photocatalysts as precursor materials for electrocatalytic water oxidation. RSC Advances, 11(19):11425-11436.

Abstract

An open-core cobalt polyoxometalate (POM) [(A-alpha-SiW9O34)Co-4(OH)(3)(CH3COO)(3)]Co8-(1) and its isostructural Co/Ni-analogue [(A-alpha-SiW9O34)Co1.5Ni2.5(OH)(3)(CH3COO)(3)]8-CoNi(2) were synthesized and investigated for their photocatalytic and electrocatalytic performance. Co(1) shows high photocatalytic O-2 yields, which are competitive with leading POM water oxidation catalysts (WOCs). Furthermore, Co(1) and CoNi(2) were employed as well-defined precursors for heterogeneous WOCs. Annealing at various temperatures afforded amorphous and crystalline CoWO4- and Co1.5Ni2.5WO4-related nanoparticles. CoWO4-related particles formed at 300 degrees C showed substantial electrocatalytic improvements and were superior to reference materials obtained from co-precipitation/annealing routes. Interestingly, no synergistic interactions between cobalt and nickel centers were observed for the mixed-metal POM precursor and the resulting tungstate catalysts. This stands in sharp contrast to a wide range of studies on various heterogeneous catalyst types which were notably improved through Co/Ni substitution. The results clearly demonstrate that readily accessible POMs are promising precursors for the convenient and low-temperature synthesis of amorphous heterogeneous water oxidation catalysts with enhanced performance compared to conventional approaches. This paves the way to tailoring polyoxometalates as molecular precursors with tuneable transition metal cores for high performance heterogeneous electrocatalysts. Our results furthermore illustrate the key influence of the synthetic history on the performance of oxide catalysts and highlight the dependence of synergistic metal interactions on the structural environment.

Abstract

An open-core cobalt polyoxometalate (POM) [(A-alpha-SiW9O34)Co-4(OH)(3)(CH3COO)(3)]Co8-(1) and its isostructural Co/Ni-analogue [(A-alpha-SiW9O34)Co1.5Ni2.5(OH)(3)(CH3COO)(3)]8-CoNi(2) were synthesized and investigated for their photocatalytic and electrocatalytic performance. Co(1) shows high photocatalytic O-2 yields, which are competitive with leading POM water oxidation catalysts (WOCs). Furthermore, Co(1) and CoNi(2) were employed as well-defined precursors for heterogeneous WOCs. Annealing at various temperatures afforded amorphous and crystalline CoWO4- and Co1.5Ni2.5WO4-related nanoparticles. CoWO4-related particles formed at 300 degrees C showed substantial electrocatalytic improvements and were superior to reference materials obtained from co-precipitation/annealing routes. Interestingly, no synergistic interactions between cobalt and nickel centers were observed for the mixed-metal POM precursor and the resulting tungstate catalysts. This stands in sharp contrast to a wide range of studies on various heterogeneous catalyst types which were notably improved through Co/Ni substitution. The results clearly demonstrate that readily accessible POMs are promising precursors for the convenient and low-temperature synthesis of amorphous heterogeneous water oxidation catalysts with enhanced performance compared to conventional approaches. This paves the way to tailoring polyoxometalates as molecular precursors with tuneable transition metal cores for high performance heterogeneous electrocatalysts. Our results furthermore illustrate the key influence of the synthetic history on the performance of oxide catalysts and highlight the dependence of synergistic metal interactions on the structural environment.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
08 Research Priority Programs > Solar Light to Chemical Energy Conversion
Dewey Decimal Classification:540 Chemistry
Scopus Subject Areas:Physical Sciences > General Chemistry
Physical Sciences > General Chemical Engineering
Uncontrolled Keywords:General Chemical Engineering, General Chemistry
Language:English
Date:1 January 2021
Deposited On:13 Jan 2022 14:13
Last Modified:27 Mar 2024 03:05
Publisher:Royal Society of Chemistry
ISSN:2046-2069
OA Status:Gold
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1039/d0ra10792a
  • Content: Published Version
  • Licence: Creative Commons: Attribution 3.0 Unported (CC BY 3.0)