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Unraveling H2 dissociation in CO2 hydrogenation on frustrated Lewis pair-functionalized UiO–67: DFT and nuclear quantum effects
(2025-12-04)
Yodsin, Nuttapon
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Udagawa, Taro
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Daengngern, Rathawat
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Jungsutthiwong, Siriporn
;
Tachikawa, Masanori
Understanding hydrogen (H<inf>2</inf>) activation is fundamental to developing efficient CO<inf>2</inf> hydrogenation catalysts. Thus, in this study, we examine H<inf>2</inf> dissociation and subsequent CO<inf>2</inf> hydrogenation on 12 UiO–67 frameworks functionalized with frustrated Lewis pairs (FLPs), employing both conventional density functional theory (DFT) and multicomponent DFT (MC_DFT) to account for nuclear quantum effects (NQEs). The results reveal that all FLP–MOFs lower the H<inf>2</inf> activation barrier through heterolytic cleavage, with NQEs further reducing the barriers—most notably in systems containing electron-donating groups (EDGs), where pronounced H–H bond elongation characterizes the transition state. Conversely, FLPs bearing strong electron-withdrawing groups stabilize the 2H adsorption state, rendering H<inf>2</inf> dissociation thermodynamically favorable but suppressing CO<inf>2</inf> hydrogenation owing to excessively strong hydrogen binding. Strong correlations are observed among H<inf>2</inf> dissociation energies, CO<inf>2</inf> hydrogenation activation barriers, and FLP acidity, enabling catalytic performance prediction. Incorporating NQEs enhances these correlations, providing a refined descriptor for rational catalyst screening. Overall, this study highlights the critical role of NQEs in hydrogen activation and demonstrates that EDG-functionalized FLP–MOFs are particularly promising candidates for promoting H<inf>2</inf> activation and CO<inf>2</inf> conversion.
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Unlocking efficient CO2–to–methanol conversion on frustrated Lewis pair-functionalized UiO–67: A synergistic approach using DFT and SISSO
(2025-10-01)
Yodsin, Nuttapon
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Pimbaotham, Pimjai
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Maihom, Thana
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Daengngern, Rathawat
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Tachikawa, Masanori
Metal–organic framework-based catalysts demonstrate considerable promise for converting CO<inf>2</inf> into valuable chemicals, particularly when combined with Frustrated Lewis Pairs (FLPs) to enhance H<inf>2</inf> dissociation during hydrogenation reactions. This study employs density functional theory (DFT) calculations to investigate modified UiO–67 frameworks wherein FLPs are introduced via eight different functional groups (UiO–67–X) into the organic linker to facilitate H<inf>2</inf> activation during CO<inf>2</inf> hydrogenation to methanol (CH<inf>3</inf>OH). The reaction proceeds through three stages: (i) hydrogenation of CO<inf>2</inf> to formic acid (HCOOH), (ii) conversion of HCOOH to formaldehyde (HCHO), and (iii) hydrogenation of HCHO to CH<inf>3</inf>OH. This study specifically focuses on steps (ii) and (iii), analyzing the detailed reaction mechanisms using optimized molecular structures and Gibbs free energy calculations to acquire insights into methanol formation on UiO–67–X. During HCOOH conversion to HCHO, adsorbed H<inf>2</inf> undergoes heterolytic cleavage at the FLP sites, producing a proton (H+) and a hydride (H−) for subsequent HCOOH hydrogenation and dehydration. The energy barriers identified at this stage represent key kinetic limitations hindering efficient CO<inf>2</inf>-to-methanol conversion. Similarly, HCHO conversion to CH<inf>3</inf>OH proceeds via H<inf>2</inf> dissociation, followed by concerted H+/H− transfer. Among the tested UiO–67–X catalysts, UiO–67–B(CH<inf>3</inf>)<inf>2</inf> exhibits the highest catalytic activity for CO<inf>2</inf> hydrogenation to methanol. Kinetic analyses are performed to assess reaction rates across a relevant temperature range, highlighting the notable influence of functional groups on catalytic performance. Additionally, the Sure Independence Screening and Sparsifying Operator (SISSO) machine-learning approach is used to identify optimal physical descriptors and derive a predictive model for the energetic span (δG), considerably lowering the computational cost associated with full reaction pathway calculations. Statistical validation confirms the robustness of these predictions. Overall, these findings underscore the vital role of FLP-assisted H<inf>2</inf> dissociation in promoting CO<inf>2</inf> hydrogenation to CH<inf>3</inf>OH, with UiO–67–B(CH<inf>3</inf>)<inf>2</inf> serving as a promising catalyst.
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Hydrogenation of CO2 to formic acid catalyzed by Co and Cu Single-atom catalysts supported on MOF-808: A DFT investigation
(2024-12-01)
Kusonjariyakun, Nawarat
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Santatiwongchai, Jirapat
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Meeprasert, Jittima
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Chotpatiwetchkul, Warot
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Maihom, Thana
In this work, DFT-based calculations and microkinetic modeling were employed to investigate CO<inf>2</inf> hydrogenation to formic acid using H<inf>2</inf> over Co and Cu single-atom catalysts supported on MOF-808. We investigated two pathways: one without the introduction of a second H<inf>2</inf> molecule (pathway A) and another one with it (pathway B). Pathway B, which involves introducing the second H<inf>2</inf> molecule alongside the formate intermediate from the first step, exhibits significantly lower energy barriers (three times lower) for the transformation into formic acid in the second step of CO<inf>2</inf> hydrogenation. Moreover, pathway B shifts the reaction thermodynamics from endergonic to exergonic, highlighting its kinetic and thermodynamic advantages. Notably, we observed formate intermediates with quasi-bidentate geometry alongside the prevalent bidentate chelating geometry. Cu2+-MOF-808 exhibits superior catalytic activity compared to Co2+-MOF-808, attributed to Cu's stronger preference for stabilizing the transition state in its square planar geometry through the Jahn-Teller effect, which is less effective in Co. Furthermore, our microkinetic modeling consistently confirms that Cu2+-MOF-808 outperforms Co2+-MOF-808 at lower temperatures, with the rate of formic acid production depending on the concentration of H<inf>2</inf>. The desorption of formic acid is identified as the rate-determining step of the reaction, significantly impacting overall efficiency.
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Effect of metal dispersion and support structure of Ni/silicalite-1 catalysts on non-thermal plasma (NTP) activated CO2 hydrogenation
(2020-09-05)
Chen, Huanhao
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Goodarzi, Farnoosh
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Mu, Yibing
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Chansai, Sarayute
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Mielby, Jerrik Jørgen
Non-thermal plasma (NTP) activated heterogeneous catalysis is a promising alternative to thermal catalysis for enabling many challenging reactions (e.g. catalytic CO<inf>2</inf> hydrogenation) under mild conditions. However, the mechanistic insight into the interaction between highly energetic electrons and vibrationally-exited reactive species with metal catalyst is still lacking. Here, catalytically active Ni nanoparticles supported on silicalite-1 zeolites with different configurations regarding the location of Ni active sites and support pore structures were comparably investigated using catalytic CO<inf>2</inf> hydrogenation under the thermal and NTP conditions. Experimental results revealed that the performance of the NTP-catalysis depends on the configuration of the catalysts significantly. Specifically, catalysts with Ni active sites sit on the outer surface of zeolite crystals (i.e. microporous Ni/S1 and Ni/M-S1@Shell with steam-assisted recrystallised micro-meso-porous structure) showed relatively good catalytic performance at a low applied voltage of 6.0 kV. Conversely, the encapsulated catalyst with hierarchical meso-micro-porous structure (i.e. Ni/D-S1) which has relatively small (i.e. average Ni particle sizes of 2.8±0.7 nm) and dispersed Ni nanoparticles (i.e. Ni dispersion of ca. 2.5 %) demonstrated comparatively the best catalytic performance (i.e. CO<inf>2</inf> conversion of ca. 75 %) at 7.5 kV. Additionally, under the NTP conditions studied, Ni on carbon-templated mesoporous silicalite-1 (Ni/M-S1) showed the worst selectivity to CH<inf>4</inf>, which was attributed to the poor accessibility of Ni active sites encapsulated in the enclosed mesopores. This study demonstrated the crucial role of catalyst design in NTP activated catalysis.

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