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Dual HER-OER performance during alkaline water splitting found in CrMnFeCo-based high-entropy materials
(2026-06-01)
Somdee, Siriwimol
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Saelee, Tinnakorn
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Khajondetchairit, Patcharaporn
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Ektarawong, Annop
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Kheawhom, Soorathep
The development of high-efficiency electrocatalyst for hydrogen production via electrochemical water splitting is crucial for advancing renewable energy technologies. However, the sluggish kinetics of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remain significant challenges. In this study, CrMnFeCoX high-entropy materials (HEMs; X = Cu, Ga, P, and Zn) are investigated as electrocatalysts for overall water splitting in alkaline media using density functional theory calculations. These HEMs are modeled using the special quasi-random structure method with a face-centered cubic (111) structure. The results revealed that the OER activity cannot be sustained due to strong adsorption of oxygenated intermediates. Specifically, the dissociation of the O-O bond in the *OOH intermediate leads to surface oxidation, which decreases activity, evidenced by the d ( p )-band center shift. Consequently, HER activity is analyzed on pristine surfaces, whereas OER activity is evaluated on oxide surfaces. The CrMnFeCoCu surface exhibits excellent HER activity, achieving a low overpotential of 0.03 V vs. RHE, attributed to effective water dissociation and moderate *H adsorption energies. Meanwhile, the CrMnFeCoP surface demonstrates superior OER activity with an overpotential of 0.39 V vs. RHE, driven by its moderate adsorption energies for oxygenated intermediates. Site-specific analyses identify Cu and Co as the primary active sites for HER and OER, respectively. These findings highlight CrMnFeCoCu and CrMnFeCoP as promising candidates for the rational design of efficient electrocatalysts for HER and OER in electrochemical water splitting.
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Bridging the Gap in Understanding the Mechanism of NH3 Formation During NO Reduction by CO in the Presence of H2O Over Rh/Al2O3 Catalysts: DFT Study
(2026-02-01)
Wangphon, Chanthip
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Khajondetchairit, Patcharaporn
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Rittiruam, Meena
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Ektarawong, Annop
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Alling, Björn
Ammonia (NH<inf>3</inf>) formation from nitric oxide (NO) and carbon monoxide (CO) in the presence of water is a promising pathway for low-temperature NO<inf>x</inf> reduction. In this work, density functional theory (DFT) calculations were used to investigate the mechanism of NH<inf>3</inf> formation on a Rh(111)/γ-Al<inf>2</inf>O<inf>3</inf>(110), in which the Rh(111) and γ-Al<inf>2</inf>O<inf>3</inf>(110) were considered separately. NO readily dissociates on the Rh site, forming N*, which reacts with CO to produce the key intermediate of NCO*. Meanwhile, water dissociates more easily on γ-Al<inf>2</inf>O<inf>3</inf>(110), providing H* species. The hydrolysis of NCO* can proceed via two pathways: on Rh(111), it forms HNCO, while on γ-Al<inf>2</inf>O<inf>3</inf>(110), it forms HNCOH*. Both intermediates subsequently decompose into NH* species, which are then hydrogenated to produce NH<inf>3</inf>. The Rh pathway is more favorable in both kinetics and thermodynamics, while the support mainly supplies hydrogen through water activation. These results suggest a dual-site mechanism in which Rh drives the main transformation, and γ-Al<inf>2</inf>O<inf>3</inf>(110) assists via hydrogen transfer. This work presents the individual roles of Rh and Al<inf>2</inf>O<inf>3</inf> surfaces in NO reduction with CO, producing NH<inf>3</inf>, which is relevant to catalytic behavior under humid conditions.
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Theoretical investigation on the role of external oxygen facilitating oxidative dehydrogenation of hydrogen sulfide on Fe-based oxide catalysts
(2025-11-15)
Saelee, Tinnakorn
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Setasuban, Sorawee
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Noppakhun, Jakapob
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Rittiruam, Meena
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Khajondetchairit, Patcharaporn
The oxidative dehydrogenation (ODH) of hydrogen sulfide (H<inf>2</inf>S) is a critical process in biogas purification, enabling cleaner and more efficient utilization of renewable energy sources. This study employs density functional theory (DFT) and microkinetic modeling to investigate the role of external oxygen (O<inf>ext</inf>) in enhancing the catalytic performance of O<inf>2</inf>/α-Fe<inf>2</inf>O<inf>3</inf>(0 0 0 1) surfaces. The findings reveal that O<inf>ext</inf> significantly lowers the activation energy of key reaction steps, promotes more favorable reaction pathways, and mitigates sulfur poisoning by stabilizing lattice oxygen and suppressing the formation of oxygen vacancies. The unique electronic and structural properties of the O<inf>2</inf>/α-Fe<inf>2</inf>O<inf>3</inf>(0 0 0 1) surface facilitate improved catalyst activity and extended operational stability, addressing key challenges in sustainable energy technologies. The existence of the O<inf>ext</inf> can decrease the optimal temperature of ODH of H<inf>2</inf>S from >1150 K on the pristine α-Fe<inf>2</inf>O<inf>3</inf>(0 0 0 1) surface to 850 K on the O<inf>2</inf>/α-Fe<inf>2</inf>O<inf>3</inf>(0 0 0 1) surface. Furthermore, undergoing the ODH reaction to the steady state is 1.25 × 10<sup>3</sup> times faster than that of a lean α-Fe<inf>2</inf>O<inf>3</inf>(0 0 0 1) surface. Also, the amount of poisoned species of S* on the O<inf>2</inf>/α-Fe<inf>2</inf>O<inf>3</inf>(0 0 0 1) surface is lowered significantly. This work advances the design of robust catalysts for efficient H<inf>2</inf>S removal by providing a deeper understanding of catalytic behavior and deactivation mechanisms. The insights presented here contribute to cleaner energy production and environmental protection, bridging fundamental knowledge and practical applications in catalysis.
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Machine learning-accelerated density functional theory optimization of PtPd-based high-entropy alloys for hydrogen evolution catalysis
(2025-11-01)
Khajondetchairit, Patcharaporn
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Somdee, Siriwimol
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Saelee, Tinnakorn
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Ektarawong, Annop
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Alling, Björn
High-entropy alloys (HEAs) have emerged as promising catalysts for the hydrogen evolution reaction (HER) due to their compositional diversity and synergistic effects. In this study, machine learning-accelerated density functional theory (DFT) calculations were employed to assess the catalytic performance of PtPd-based HEAs with the formula PtPdXYZ (X, Y, Z = Fe, Co, Ni, Cu, Ru, Rh, Ag, Au; X ≠ Y ≠ Z). Among 56 screened HEA(111) surfaces, PtPdRuCoNi(111) was identified as the most promising, with adsorption energies (E<inf>ads</inf>) between −0.50 and −0.60 eV and high d-band center of −1.85 eV, indicating enhanced activity. This surface showed the hydrogen adsorption free energy (ΔG<inf>H*</inf>) of −0.03 eV for hydrogen adsorption, outperforming Pt(111) by achieving a better balance between adsorption and desorption. Machine learning models, particularly extreme gradient boosting regression (XGBR), significantly reduced computational costs while maintaining high accuracy (root-mean-square error, RMSE = 0.128 eV). These results demonstrate the potential of HEAs for efficient and sustainable hydrogen production.
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First-Principles Screening of 3d-Transition-Metal-Doped Hydrous Cobalt Phosphate Catalysts for Enhanced Oxygen Evolution Reaction
(2025-09-01)
Rittiruam, Meena
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Saelee, Tinnakorn
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Khajondetchairit, Patcharaporn
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Ektarawong, Annop
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Alling, Björn
Hydrous cobalt phosphate (CoPO) is a promising OER catalyst, but its activity is limited by poor electron transport and weak intermediate binding. This study reveals how 3d transition metal dopants can be used to tune these properties through first-principles calculations. Sc, Ti, V, and Cr improve catalytic activity by promoting electron transfer and stabilizing *O intermediates, while Mn, Fe, Cu, and Zn reduce performance. Among all candidates, Ni doping strikes the optimal balance, enhancing conductivity and providing moderate *O binding energy that minimizes overpotential. These trends follow electronic descriptors such as d-band center and electronegativity, and are validated by volcano plot analysis. Ni-CoPO emerges as the most effective design, offering a clear strategy for improving OER catalysts by controlling dopant identity and electronic structure.
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The development of configurational entropy formulation for high-entropy oxides: Review and outlook
(2025-08-10)
Tiwtusthada, Sirapat
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Saelee, Tinnakorn
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Khajondetchairit, Patcharaporn
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Rittiruam, Meena
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Praserthdam, Piyasan
High-entropy oxides (HEOs) have garnered significant attention due to their unique ability to stabilize disordered phases through configurational entropy. In this review, we delve into both the theoretical and practical implications of configurational entropy to classify low, medium, and high entropy materials, underscoring its vital role of multiple sublattice and defects of cation and anion in influencing phase stability, structural intricacy, and functional performance. We extend our discussion to encompass the four core effects of HEMs, and non-configurational entropy contributions, namely vibrational, electronic, magnetic, entropy, and dislocation entropy, and evaluate how their collective effects shape the overall thermodynamic behavior of these materials. Advanced entropy models that incorporate multi-sublattice configurations, anion defects, and short-range order are critically evaluated, with computational simulations and machine-learned interaction potentials serving as complementary tools. Additionally, high-throughput experimental and computational explorations are highlighted as essential methods for validating these theoretical models. By examining the interplay between configurational and non-configurational entropy, this review illuminates their combined influence on the properties and performance of HEOs. Ultimately, we identify current challenges and opportunities, advocating for integrative computational and experimental strategies to broaden the compositional landscape of high-entropy materials (HEMs) and facilitate their rational design for advanced applications in energy conversion, catalysis, and high-temperature environments.
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A combined DFT-Experimental study on FSP-made Ru/Ti-SiO2 catalysts for CO2 methanation
(2025-07-01)
Mekasuwandumrong, Okorn
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Saelee, Tinnakorn
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Noppakhun, Jakapob
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Rittiruam, Meena
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Khajondetchairit, Patcharaporn
Flame spray pyrolysis (FSP) was employed to synthesize Ti-modified SiO₂ in a single step, serving as the support for Ru-based catalysts in CO₂ methanation reactions. The addition of Ti led to the formation of anatase and rutile TiO₂ phases, enhancing the catalytic activity of Ru/Ti-SiO₂ catalysts. Benchmarking between Ru/Ti-SiO₂ catalysts of various Ti concentrations prepared using one-step FSP techniques indicated significantly higher catalytic activity for the impregnation-made catalysts compared to the FSP-made ones, where diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed different CH₄ formation mechanisms between two techniques. For FSP-made catalysts, it predominantly occurred through the CO route, whereas the impregnation-made proceed via both the dissociative adsorption of CO₂ (CO route) and through surface formate species formation. To explain the effect of Ti loading on Ru/SiO₂ catalysts, a multiscale analysis combining density functional theory (DFT) and microkinetic modeling was performed to study the adsorption behavior of CO₂ on different catalysts. The results revealed that a high amount of Ti reduced the adsorption strength of CO₂ on Ru/SiO₂ catalysts, indicating a modified interaction between CO₂ and the catalyst surface.
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Machine-learning-accelerated density functional theory screening of Cu-based high-entropy alloys for carbon dioxide reduction to ethylene
(2025-03-01)
Rittiruam, Meena
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Khamloet, Pisit
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Tiwtusthada, Sirapat
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Ektarawong, Annop
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Saelee, Tinnakorn
Computational screening of high-entropy alloy (HEA) catalysts as alternatives to the typical Cu electrocatalyst for CO<inf>2</inf> reduction reaction (CO<inf>2</inf>RR) has been extensively focused on C<inf>1</inf> products, but C<inf>2+</inf> products have received significantly less attention. This work optimized CuZnPdAgAu HEA catalyst composition for CO<inf>2</inf>RR to ethylene via density functional theory and supervised machine learning regression techniques. Candidates were identified from 106,045 HEA data for enthalpy of adsorption of *CO<inf>2</inf>, *H, *HOCCOH, and *C<inf>2</inf>H<inf>4</inf> species, and the Gibbs free energy of *H. The electrocatalytic properties during the reaction were examined on the surface of the optimized HEA candidate – Cu<inf>0.36</inf>Zn<inf>0.18</inf>Pd<inf>0.10</inf>Ag<inf>0.18</inf>Au<inf>0.18</inf> benchmarked to Cu (111). The Pd site of such a candidate functions as the active site for the CO<inf>2</inf> activation step. In terms of catalytic activity, it showed lower Gibbs free energy for the potential determining step – the *OCCOH formation step compared to that on the Cu (111). Insight into electronic properties demonstrated that the candidate reduces the uphill reaction energy for *HOCCOH production pathway due to increased electron density in the C–C bond, donated from two Cu sites. It is shown that the HEA catalyst candidate has the potential for CO<inf>2</inf>RR targeting ethylene, an alternative to a common Cu catalyst.
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Determining the role of oxygen vacancies in palmitone selectivity and coke formation over acid metal oxide catalysts for the ketonization of methyl palmitate
(2021-11-25)
Guntida, Adisak
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Rattanachartnarong, Thanwarat
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Jongsomjit, Bunjerd
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Sooknoi, Tawan
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Weerachawanasak, Patcharaporn
In the present study, TiO<inf>2</inf>, CeO<inf>2</inf>, MnO<inf>2</inf>, and ZrO<inf>2</inf> catalysts were used to investigate the catalytic performance in methyl palmitate ketonization. The reaction was accelerated by weak Lewis acid, while the oxygen vacancies promoted the palmitone selectivity. The use of various characterization techniques revealed that oxygen vacancies played an important role for trapping the hydrogen atom and inhibited its spillover. This caused the suppression of the Lewis acid transformation to new Bronsted acid. Thus, the cracking of palmitone over the new Bronsted acid was diminished, leading to the decrement of selectivity to undesired products. However, when the hydrogen atom was trapped in the oxygen vacancies, the coke deposition was dominant. This phenomenon arose because hydrogen could not suppress the deep dehydrogenation, resulting in the transformation of aliphatic coke to aromatic coke. The role of oxygen vacancies was determined, and it had the positive effect on the palmitone selectivity, whereas it raised the coke formation.
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Preface
(2021-09-20)
Thammavintorn, Preecha
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Limkaisang, Viroj
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Charoenprakdee, Anek
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Seetawan, Tosawat
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Kimura, Kaoru

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