Non-Thermal Contribution to Ruthenium Photothermal Catalyst in Carbon Dioxide Methanation
type: CreativeWork
description: Global economic growth has been accompanied by an increase in energy consumption and the release of CO2 into the atmosphere. Photothermal catalysis offers a promising strategy for sustainable chemical transformations by combining thermal and photonic energy to accelerate reactions under mild conditions to convert greenhouses into energy sources. However, quantifying non-thermal contributions, particularly those arising from hot electrons, remains a major challenge due to limitations in temperature measurement and mechanistic ambiguity. This dissertation addresses these challenges through the development of a non-contact near-infrared (NIR) optical thermometer capable of accurately measuring catalyst surface temperature independent of emissivity. By fitting the continuous NIR emission spectrum (950–1600 nm), this technique achieves ±1 °C accuracy above 200 °C, enabling reliable distinction between thermal and non-thermal effects. Using Ru–SiO2 as a model system for CO₂ methanation, we demonstrate over 100-fold enhancement in CH4 production in blue light compared to green light. The reaction rate scales nearly linearly with light intensity and exhibits a sharp spectral cutoff near 500 nm, disappearing at longer wavelengths. This wavelength dependence suggests a non-thermal mechanism beyond simple heating. By integrating precise temperature monitoring, studying dependence on photon energy and intensities with and without external heating, this work establishes a mechanistic framework for validating non-thermal contributions in photothermal catalysis. The approach is generalizable to other catalytic systems and offers design principles for next-generation catalysts that leverage light–matter interactions to enhance selectivity, reduce activation barriers, and enable sustainable chemical transformations.
abstract: Global economic growth has been accompanied by an increase in energy consumption and the release of CO2 into the atmosphere. Photothermal catalysis offers a promising strategy for sustainable chemical transformations by combining thermal and photonic energy to accelerate reactions under mild conditions to convert greenhouses into energy sources. However, quantifying non-thermal contributions, particularly those arising from hot electrons, remains a major challenge due to limitations in temperature measurement and mechanistic ambiguity. This dissertation addresses these challenges through the development of a non-contact near-infrared (NIR) optical thermometer capable of accurately measuring catalyst surface temperature independent of emissivity. By fitting the continuous NIR emission spectrum (950–1600 nm), this technique achieves ±1 °C accuracy above 200 °C, enabling reliable distinction between thermal and non-thermal effects. Using Ru–SiO2 as a model system for CO₂ methanation, we demonstrate over 100-fold enhancement in CH4 production in blue light compared to green light. The reaction rate scales nearly linearly with light intensity and exhibits a sharp spectral cutoff near 500 nm, disappearing at longer wavelengths. This wavelength dependence suggests a non-thermal mechanism beyond simple heating. By integrating precise temperature monitoring, studying dependence on photon energy and intensities with and without external heating, this work establishes a mechanistic framework for validating non-thermal contributions in photothermal catalysis. The approach is generalizable to other catalytic systems and offers design principles for next-generation catalysts that leverage light–matter interactions to enhance selectivity, reduce activation barriers, and enable sustainable chemical transformations.
author: Chirom, Meiraba Meitei 1997-
language: English
keywords: Plasmonics, CO2 methanation, Non contact thermometry, Photothermal catalysis, Non-thermal contribution, Reaction mechanism, Ruthenium catalyst
date published: 2025-12
date modified: 2026-07-24T02:31:59Z
provider: University of Houston
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Houston

PropertyValue
property ID: Handle
value: https://hdl.handle.net/10657/20920