Deciphering the reaction mechanisms of photothermal hydrogen production using H/D kinetic isotope effect

Hakim, Sara El; Chave, Tony; Nikitenko, Sergey I.

doi:10.1039/d2cy01185a

Cited by 4 publications

(7 citation statements)

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“…over a Ti@TiO2 core-shell photocatalyst is mainly attributed to the electron-hole-mediated splitting of the O-H bond from glycerol [9]. On the other hand, the dynamics of intermediates at the catalyst surface could also contribute to the overall reaction kinetics through the entropy of activation.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, these values are comparable with the E a measured previously for reforming glycerol with the same catalyst [19], which implies a similarity in the reaction mechanism for these sacrificial reagents. Earlier studies have noticed that the photothermal effect during the photolysis of glycerol with Ti@TiO 2 NPs is attributed to the thermally induced transfer of photogenerated, shallowly trapped electron holes to highly reactive free holes, h + , at the surface of TiO 2 [9]. Further electronhole-mediated cleavage of the O-H bond from glycerol could lead to H 2 formation.…”

Section: Resultsmentioning

confidence: 99%

“…On the basis of the above results, it is evident that a rather low Ea value for t-Bu in comparison with 1-BuOH/2-BuOH isomers (Table 1) reflects the significant influe of C-C bond scission on the photothermal effect with t-BuOH. As aforementioned, photothermal reforming of primary and secondary alcohols in the presence of TiO2-ba photocatalysts deals with the mobility of photogenerated h + [9,27,28]. In the system w t-BuOH, there are two possible reaction pathways for t-BuOH photoconversion: h + On the basis of the above results, it is evident that a rather low E a value for t-BuOH in comparison with 1-BuOH/2-BuOH isomers (Table 1) reflects the significant influence of C-C bond scission on the photothermal effect with t-BuOH.…”

Section: Resultsmentioning

confidence: 99%

“…In the system w t-BuOH, there are two possible reaction pathways for t-BuOH photoconversion: h + On the basis of the above results, it is evident that a rather low E a value for t-BuOH in comparison with 1-BuOH/2-BuOH isomers (Table 1) reflects the significant influence of C-C bond scission on the photothermal effect with t-BuOH. As aforementioned, the photothermal reforming of primary and secondary alcohols in the presence of TiO 2 -based photocatalysts deals with the mobility of photogenerated h + [9,27,28]. In the system with t-BuOH, there are two possible reaction pathways for t-BuOH photoconversion: h + -mediated O-H bond cleavage similar to that with 1-BuOH/2-BuOH isomers (Reactions 5,6), and [16]:…”

Section: Resultsmentioning

confidence: 99%

“…However, the data about dominating photothermal mechanisms during H 2 production are still scarce in the literature. Recent studies of the H/D kinetic isotope effect revealed that the photothermal effect in the process of reforming aqueous glycerol over a Ti@TiO 2 core-shell photocatalyst is mainly attributed to the electron-hole-mediated splitting of the O-H bond from glycerol [9]. On the other hand, the dynamics of intermediates at the catalyst surface could also contribute to the overall reaction kinetics through the entropy of activation.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Butanol Isomerization on Photothermal Hydrogen Production over Ti@TiO2 Core-Shell Nanoparticles

et al. 2022

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In this work, we reported for the first time the effect of butanol isomerization on the photothermal production of hydrogen in the presence of a noble, metal-free Ti@TiO2 core-shell photocatalyst. The experiments were performed in aqueous solutions of 1-BuOH, 2-BuOH, and t-BuOH under Xe lamp irradiation (vis/NIR: 8.4 W, UV: 0.6 W) at 35–69 °C. The increase in temperature significantly enhanced H2 formation, indicating a strong photothermal effect in the studied systems. However, in dark conditions, H2 emission was not observed even at elevated temperatures, which clearly points out the photonic origin of H2 photothermal formation. The rate of H2 production followed the order of 1-BuOH>>2-BuOH>t-BuOH in the entire range of studied temperatures. In the systems with 1-BuOH and 2-BuOH, hydrogen was the only gaseous product measured online in the outlet carrier argon using mass spectrometry. By contrast, a mixture of H2, CH4, and C2H6 was detected for t-BuOH, indicating a C–C bond scission with this isomer during photocatalytic degradation. The apparent activation energies, Ea, with 1-BuOH/2-BuOH isomers (20–21 kJ·mol−1) was found to be larger than for t-BuOH (13 kJ·mol−1). The significant difference in thermal response for 1-BuOH/2-BuOH and t-BuOH isomers was ascribed to the difference in the photocatalytic mechanisms of these species. The photothermal effect with 1-BuOH/2-BuOH isomers can be explained by the thermally induced transfer of photogenerated, shallowly trapped electron holes to highly reactive free holes at the surface of TiO2 and the further hole-mediated cleavage of the O-H bond. In the system with t-BuOH, another mechanism could also contribute to the overall process through hydrogen abstraction from the C–H bond by an intermediate •OH radical, leading to CH3• group ejection. Formation of •OH radicals during light irradiation of Ti@TiO2 nanoparticle suspension in water has been confirmed using terephthalate dosimetry. This analysis also revealed a positive temperature response of •OH radical formation.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Butanol Isomerization on Photothermal Hydrogen Production over Ti@TiO2 Core-Shell Nanoparticles

et al. 2022

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Boosting Formate Electrooxidation by Heterostructured PtPd Alloy and Oxides Nanowires

Wang,

Sun,

et al. 2024

Advanced Materials

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Direct formate fuel cells (DFFCs) receive increasing attention as promising technologies for the future energy mix and environmental sustainability, as formate can be made from carbon dioxide utilization and is carbon neutral. Herein, heterostructured PtPd alloy and oxides nanowires (PtPd‐ox NWs) with abundant defect sites are synthesized through a facile self‐template method and demonstrated high activity towards formate electrooxidation reaction (FOR). The electronic tuning arising from the heterojunction between alloy and oxides influence the work function of PtPd‐ox NWs. The sample with optimal work function reveals the favorable adsorption behavior for intermediates and strong interaction in the d−p orbital hybridization between Pt site and oxygen in formate, favoring the FOR direct pathway with a low energy barrier. Besides the thermodynamic regulation, the heterostructure can also provide sufficient hydroxyl species to facilitate the formation of carbon dioxide due to the ability of combining absorbed hydrogen and carbon monoxide at adjacent active sites, which contributes to the improvement of FOR kinetics on PtPd‐ox NW. Thus, heterostructured PtPd‐ox NWs achieve dual regulation of FOR thermodynamics and kinetics, exhibiting remarkable performance and demonstrating potential in practical systems.This article is protected by copyright. All rights reserved

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Light-to-heat conversion and photothermal hydrogen evolution over magnetic nitinol photocatalyst

Nikitenko,

El Hakim,

Le Goff

et al. 2024

International Journal of Hydrogen Energy

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Deciphering the reaction mechanisms of photothermal hydrogen production using H/D kinetic isotope effect

Abstract: H/D kinetic isotope effect has been employed to study the mechanism of the thermally assisted photocatalytic hydrogen production over noble metal-free Ti@TiO2 core-shell nanoparticles. We have found that the observed...

Cited by 4 publications

References 24 publications

Influence of Butanol Isomerization on Photothermal Hydrogen Production over Ti@TiO2 Core-Shell Nanoparticles

Influence of Butanol Isomerization on Photothermal Hydrogen Production over Ti@TiO2 Core-Shell Nanoparticles

Boosting Formate Electrooxidation by Heterostructured PtPd Alloy and Oxides Nanowires

Light-to-heat conversion and photothermal hydrogen evolution over magnetic nitinol photocatalyst

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