Dynamic redox chemistry overrides insulator-to-metal transition control of illuminated methane oxidation over La 1− x Sr x CoO 3− δ perovskites
Abstract
Insulator-to-metal transitions (IMTs) have emerged as a potential strategy for tuning catalyst response to illumination by modifying electronic transport behaviour. However, whether the electronic character associated with the pristine IMT remains operative under redox-active reaction environments remains unclear. In this work, La1−xSrxCoO3−δ (LSCO-x, x = 0.0–0.4) was employed as a model perovskite series that exhibits a composition-driven IMT to assess whether changes in electronic character, from insulating (x < 0.2) to metallic-like (x ≥ 0.2), influence catalyst behaviour under illumination using methane oxidation as a probe reaction. Under full-spectrum illumination, all compositions stabilised at a similar bed temperature (250 ± 5 °C) and methane conversion followed thermal-only activity trends. Illumination induced a photothermal heating effect, with both transient absorption spectroscopy and light-heat decoupling experiments suggesting no carrier-mediated contributions under the conditions tested. The behaviour is consistent with lattice oxygen participation through a Mars and van Krevelen mechanism, where reaction-induced oxygen-vacancy formation perturbs the electronic transport character associated with the pristine IMT. This dynamic defect chemistry plausibly disrupts electronic transport pathways, shifting the system into a photothermal-dominated regime irrespective of the pristine electronic transport character. Overall, the findings demonstrate that under methane oxidation conditions, a composition-driven IMT does not translate into a tuneable photo-response, highlighting that IMT-derived electronic structure transitions are a reaction environment sensitive design parameter.
Related
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BibTeX
@article{elkington2026dynamic,
title = {{Dynamic redox chemistry overrides insulator-to-metal transition control of illuminated methane oxidation over La 1− x Sr x CoO 3− δ perovskites}},
author = {Elise Elkington and Syed Hamad Ullah Shah and Yi Fen Zhu and Clement Nicollet and Michael P Nielsen and Rose Amal and Jason Scott and Emma C Lovell},
journal = {EES Catalysis},
year = {2026},
month = sep,
doi = {10.1039/d6ey00161k},
url = {https://hal.science/hal-05754421v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Dynamic redox chemistry overrides insulator-to-metal transition control of illuminated methane oxidation over La 1− x Sr x CoO 3− δ perovskites
AU - Elise Elkington
AU - Syed Hamad Ullah Shah
AU - Yi Fen Zhu
AU - Clement Nicollet
AU - Michael P Nielsen
AU - Rose Amal
AU - Jason Scott
AU - Emma C Lovell
PY - 2026
DA - 2026/09/18
JO - EES Catalysis
DO - 10.1039/d6ey00161k
UR - https://hal.science/hal-05754421v1
AB - Insulator-to-metal transitions (IMTs) have emerged as a potential strategy for tuning catalyst response to illumination by modifying electronic transport behaviour. However, whether the electronic character associated with the pristine IMT remains operative under redox-active reaction environments remains unclear. In this work, La1−xSrxCoO3−δ (LSCO-x, x = 0.0–0.4) was employed as a model perovskite series that exhibits a composition-driven IMT to assess whether changes in electronic character, from insulating (x < 0.2) to metallic-like (x ≥ 0.2), influence catalyst behaviour under illumination using methane oxidation as a probe reaction. Under full-spectrum illumination, all compositions stabilised at a similar bed temperature (250 ± 5 °C) and methane conversion followed thermal-only activity trends. Illumination induced a photothermal heating effect, with both transient absorption spectroscopy and light-heat decoupling experiments suggesting no carrier-mediated contributions under the conditions tested. The behaviour is consistent with lattice oxygen participation through a Mars and van Krevelen mechanism, where reaction-induced oxygen-vacancy formation perturbs the electronic transport character associated with the pristine IMT. This dynamic defect chemistry plausibly disrupts electronic transport pathways, shifting the system into a photothermal-dominated regime irrespective of the pristine electronic transport character. Overall, the findings demonstrate that under methane oxidation conditions, a composition-driven IMT does not translate into a tuneable photo-response, highlighting that IMT-derived electronic structure transitions are a reaction environment sensitive design parameter.
SN - 2753-801X
ER -