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Complete solar thermal direct reduction of iron ore by hydrogen in a particle-fed reactor under concentrated sunlight
(2026-06-01)
Abanades, Stéphane
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Garcia, Roger
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Chuayboon, Srirat
Solar iron production from H<inf>2</inf>-based direct reduction of iron ore was investigated in a continuously particle-fed reactor for performance analysis. Concentrated solar energy was used as the external source of high-temperature process heat and hydrogen was used as reductant, thereby enabling decarbonation of the iron-making process. The solar reactor featured a rotary kiln composed of a refractory conical cavity, in which the reacting particles were injected and extracted under a flow of H<inf>2</inf> reductant, subjected to real concentrated solar irradiation. The reactor was experimentally tested under both continuous and semi-continuous operation modes to determine and compare the key performance metrics. The on-sun experiments focused on unraveling the effect of the cavity material and operating mode on the process performance including H<inf>2</inf> consumption, particle conversion, and iron product purity. A cavity made of mullite appeared unfavorable for continuous particle flow due to agglomeration and adherence to the walls. Conversely, boron nitride promoted particle flowability while totally eliminating adhesion to the walls. In continuous mode, the conversion was kinetically limited due to a low particle residence time in the cavity. Semi-continuous operation was thus tested with cavity rotation turned off during injection and rotation turned on for particles extraction, which warranted a high-enough reaction duration with particle conversion approaching completion. Maximum conversion up to 99 % was achieved with complete recovery yield of the converted product at the reactor outlet. Characterization of solid products (XRD, SEM/EDX) confirmed the successful production of pure sponge iron. Further scaling-up of the solar reactor concept with longer cavity length will enhance the particle residence time, thereby favoring their conversion in continuous mode.
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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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Enhanced hydrogen production by green alga Scenedesmus obliquus TISTR 8546 under atmospheric air through potassium deprivation and cysteine supplementation
(2026-03-01)
Sereetrakul, Kodchaporn
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Taikhao, Samart
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Chinchusak, Nattanon
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Phunpruch, Saranya
Hydrogen is a promising alternative energy carrier that can be produced by green microalgae. However, the key enzyme catalyzing this process, [FeFe]‑hydrogenase, is highly sensitive to O<inf>2</inf> generated during photosynthesis, which severely restricts its activity. This study aimed to screen the microalgal strain capable of producing high levels of H<inf>2</inf> in the presence of O<inf>2</inf> and to enhance H<inf>2</inf> production yields using O<inf>2</inf>-scavenging strategies to levels comparable to or exceeding those achieved under anaerobic conditions. Among the 24 strains tested, Scenedesmus obliquus TISTR 8546 demonstrated the highest H<inf>2</inf> production under both aerobic and anaerobic conditions. The O<inf>2</inf>I<inf>50</inf> of S. obliquus TISTR 8546 cells for H<inf>2</inf> evolution was 15.93 ± 0.24%. Potassium deprivation significantly enhanced H<inf>2</inf> production and hydrogenase activity by lowering O<inf>2</inf> levels through reduced photosynthetic O<inf>2</inf> evolution and increased dark respiration. Moreover, potassium deprivation promoted intracellular starch accumulation, providing reducing equivalents for H<inf>2</inf> generation. Cysteine supplementation further stimulated H<inf>2</inf> production by serving as a reducing agent. S. obliquus TISTR 8546 exhibited a maximum H<inf>2</inf> production rate of 22.92 ± 1.05 μmol H<inf>2</inf> mg Chl−1 h−1 and achieved a maximum cumulative H<inf>2</inf> production of 1153.78 ± 52.65 μmol H<inf>2</inf> mg Chl−1 when incubated in potassium-deprived TAP medium supplemented with 0.1 mM cysteine under atmospheric air for 6 days. This rate was 23.6- and 2.7-fold higher than those obtained in TAP and TAP-K media, respectively. These findings demonstrate the potential of S. obliquus TISTR 8546 as a robust microalgal strain for sustainable H<inf>2</inf> production under atmospheric air, highlighting its promise for future industrial applications.
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Improvement in the Uniformity of Bismuth Distribution in an Al-Bi Alloy by Ultrasonic Processing and Hydrogen Melt Enrichment
(2026-01-01)
Chankitmunkong, Suwaree
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Eskin, Dmitry G.
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Diewwanit, Onnjira
Manufacturing of immiscible metallic alloysMetallic alloys, such as aluminumAluminum-bismuth, faces challenges in achieving uniform distribution of secondary phase droplets/particles due to their higher density and tendency to agglomerate/coalesce, which negatively affects mechanical propertiesMechanical properties. Recent studies on emulsification of immiscible liquids showed that ultrasonic treatment (UST) of gas-saturated systems improved the droplet distribution. In this work we tested this approach on Al-Bi alloys with melts saturated with hydrogenHydrogen. It was demonstrated that this combination resulted in the uniform distribution of fineFines Bi droplets in the aluminumAluminum matrix. UST had a dual role in the process: (a) increased cavitation facilitated by dissolved hydrogenHydrogen improved the efficiency of droplet formation and distribution and (b) ultrasonic degassing eliminated the adverse effects of gas porosity. Finer and evenly distributed Bi particles enhanced the wear resistance of the alloy.
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Renewable and sustainable green energy generation using Bi-functional TMOs decorated layered carbon nitride anchored on MXene for oxygen evolution reactions and urea oxidation reaction performance
(2025-12-01)
Vasu, Dhanapal
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Vittayakorn, Naratip
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Chang, Shih Hsien
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Lin, Kai Hsuan
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Chiu, Te Wei
This article presents a comprehensive evaluation of a novel V<inf>2</inf>O<inf>5</inf>–graphitic carbon nitride (gCN)/MXene (Ti<inf>3</inf>C<inf>2</inf>Tx) composite (VGM) electrocatalyst, designed to enhance the oxygen evolution reaction (OER) and urea oxidation reaction (UOR). The VGM material was synthesized through a combination of hydrofluoric acid (HF) etching and thermal polymerization, offering a new approach for integrating transition metal oxides with 2D materials. Structural and surface analyses confirmed the successful formation of the hybrid catalyst with well-defined morphology and composition. Electrochemical studies revealed an impressively low overpotential of 151 mV and a Tafel slope of 95 mV/dec for OER, indicating excellent catalytic efficiency. The hybrid structure synergistically combines the high redox activity of V<inf>2</inf>O<inf>5</inf>, the large surface area of gCN, and the conductivity of MXene, leading to superior electrochemical performance. Additionally, the catalyst effectively drives the UOR, enabling simultaneous hydrogen generation and urea-rich wastewater remediation. This work introduces a cost-effective and multifunctional electrocatalyst design strategy, offering both energy and environmental benefits.
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Boosting sustainable hydrogen production via water splitting and urea oxidation using spinel hollow-sphere nano catalysts
(2025-10-01)
Lin, Hsin Yu
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Vasu, Dhanapal
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Tsang, Chun Han
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Hsu, Cheng Shan
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Prashanth, Gopi
In this study, spinel MgCo<inf>2</inf>O<inf>4</inf> materials were synthesized using three different techniques: freeze-drying, solid-state, and hydrothermal methods, to evaluate their structural, morphological, and electrocatalytic properties. Comprehensive characterization techniques including XRD, Raman spectroscopy, FT-IR, FESEM, HRTEM, and XPS confirmed the successful formation of phase-pure MgCo<inf>2</inf>O<inf>4</inf> with varied morphologies. Among the synthesized materials, the freeze-dried sample exhibited a well-defined hollow-sphere structure, providing abundant electroactive sites and superior electron/mass transport pathways. This morphology contributed to outstanding electrocatalytic performance. For the oxygen evolution reaction (OER), the hollow-sphere MgCo<inf>2</inf>O<inf>4</inf> catalyst demonstrated a low overpotential of 430 mV at 10 mA cm−2 and a Tafel slope of 190 mV dec−1. In addition, the same catalyst exhibited excellent activity for the urea oxidation reaction (UOR), with a Tafel slope of 95 mV dec−1 and enhanced current density under alkaline conditions. The superior UOR activity, enabled by the lower oxidation potential of urea (∼0.37 V vs. RHE), also highlights its potential for energy-efficient hydrogen production and wastewater treatment. This work establishes a scalable and cost-effective strategy to synthesize high-performance MgCo<inf>2</inf>O<inf>4</inf> hollow-sphere electrocatalysts, paving the way for their application in sustainable energy and environmental technologies.
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Physiological and Environmental Factors Influencing Hydrogen Production by Unicellular Green Alga Monoraphidium sp. KMITL-1
(2025-10-01)
Krutpan, Varanya
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Supakriangkrai, Thaninthorn
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Lohasupthawee, Pana
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Phunpruch, Saranya
With the growing global energy demand and the urgent need to reduce carbon emissions, hydrogen (H<inf>2</inf>) has emerged as a promising clean energy carrier. Among various biological H<inf>2</inf> production, green algae present a sustainable and eco-friendly alternative due to their ability to produce H<inf>2</inf> via photobiological pathways. This study aimed to investigate H<inf>2</inf> production by unicellular green alga Monoraphidium sp. KMITL-1, isolated from hydroponic water at the Plant Tissue Culture Laboratory, King Mongkut’s Institute of Technology Ladkrabang. The taxonomic identity of the strain, belonging to the genus Monoraphidium within the Selenastraceae family, was confirmed through morphological observation and molecular characterization using 23S plastid rRNA gene sequencing. Various physiological and environmental parameters influencing H<inf>2</inf> production were evaluated, including cell age, cell density, nutrient deprivation, carbon source, pH, temperature, and light intensity. A 24-hour-old culture with an OD<inf>750</inf> of 0.8 exhibited a significant increase in H<inf>2</inf> production. The optimal medium was potassium-deprived Tris-acetate-phosphate (TAP-K) supplemented with glucose at a concentration of 350 mmol C-atom L-1. The ideal environmental conditions for H<inf>₂</inf> production were pH 7.2, a temperature of 30 °C, and a light intensity of 60 μmol photons m-2 s-1. Under these optimized conditions, Monoraphidium sp. KMITL-1 achieved a maximum H<inf>2</inf> production rate of 67.976 ± 1.096 μmol H<inf>2</inf> mg Chl-1 h-1 and a cumulative H<inf>2</inf> yield of 3,190.436 ± 2.219 μmol H<inf>2</inf> mg Chl-1 after 72 h of incubation. These results highlight the potential of Monoraphidium sp. KMITL-1 for large-scale biohydrogen production and its applicability in the development of sustainable energy technologies.
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A Review of Converters for Green Hydrogen Generation in Consideration of Renewable Energy
(2024-01-01)
Vivanthanarot, Saman
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Khomfoi, Surin
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Phophongviwat, Teeraphon
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Somboonpanya, Nattapon
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Phongsawat, Suwaphit
Hydrogen is set to revolutionize the future energy landscape with its wide-ranging applications across various sectors. With global decarbonization objectives, water electrolysis provides a sustainable way to produce hydrogen, especially when it is driven by renewable energy sources. This process predominantly utilizes grid electricity, but the growing implementation of renewable energy-powered microgrids presents an attractive alternative for hydrogen production. The produced hydrogen can be used not only for electrical generation within the microgrid but also for local heating and as a fuel for transportation. Power converters are crucial in ensuring stability and reliability in hydrogen production. The paper reviews the power electronics converters required to match the DC and AC voltage source with the needs of electrolyzers. Moreover, this paper explores the technologies of electrolyzers powered by renewable energy sources, with a particular focus on wind turbines and PV.
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Effect of CoMo metal loading on H2 and CNTs production from biogas by integrative process
(2022-12-19)
Aieamsam-Aung, Pichawee
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Nantapong, Paveenuch
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Rattanaamonkulchai, Raminda
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Kludpantanapan, Thunyathon
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Srifa, Atthapon
Effect of CoMo metal loading to MgO (1, 5, 30 and 50 wt%) on conversion of biogas by an integrative process was investigated at 900 °C under atmospheric pressure. The integrative process combines the direct methanation of CO<inf>2</inf> in biogas and the CH<inf>4</inf> decomposition to upgrade biogas to CH<inf>4</inf> and decompose to hydrogen and carbon nanotubes. Methane dissociative reaction is governed by the concentration of active metals on the catalyst surface, while DRM reaction is suppressed. The 30 wt%CoMo catalyst shows the optimal loading for production of high-purity H<inf>2</inf> (>90v/v%) and high yield of MWCNTs (2.33 gCNT/gCat-h) with 100%CO<inf>2</inf> conversion and 95%CH<inf>4</inf> conversion. Meanwhile, 1 wt%CoMo catalyst provided the single-walled CNTs with diameter of 2.5 nm, high surface area of 165 m2/g and high graphitization of I<inf>G</inf>/I<inf>D</inf> = 6.14.
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Simultaneous production of hydrogen and carbon nanotubes from biogas: On the design of combined process
(2022-04-15)
Rattanaamonkulchai, Raminda
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Kludpantanapan, Thunyathon
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Nantapong, Paveenuch
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Srifa, Atthapon
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Koo-Amornpattana, Wanida
We introduced a novel combined process of CO<inf>2</inf> methanation (METH) and catalytic decomposition of methane (CDM) for simultaneous production of hydrogen (H<inf>2</inf>) and carbon nanotubes (CNTs) from biogas. In this process, biogas is catalytically upgraded into CH<inf>4</inf>-rich gas in METH reactor using Ni/CeO<inf>2</inf> catalyst, and the obtained CH<inf>4</inf>-rich gas is subsequently decomposed into H<inf>2</inf> and CNTs in CDM reactor over CoMo/MgO catalyst. Among the three different process scenarios proposed, the combined process with a steam condenser equipped between METH and CDM reactors could greatly improve a CNTs productivity. The CNTs production yield increased by more than 2.5-fold, maximizing at 9.08 gCNTs/gCat with a CNTs purity of 90%. The deposited carbon product was characterized as multi-walled carbon nanotubes (MWCNTs) with a surface area of 136.0 m2/g, comparable with commercial CNTs of 199.8 m2/g. The remarkable I<inf>G</inf>/I<inf>D</inf> ratio of 2.18 confirms a superior portion of graphitic carbon in the synthesized CNTs upon the commercial CNTs with I<inf>G</inf>/I<inf>D</inf> = 0.74. Notably, the CH<inf>4</inf> conversion reached 94.5%, while the CO<inf>2</inf> conversion achieved 100%, resulting in the H<inf>2</inf> yield and H<inf>2</inf> purity higher than 90%. This combined process demonstrates a promising route for production of high quality CNTs and high purity H<inf>2</inf> with complete CO<inf>2</inf> conversion using biogas as abundant renewable energy resources. In addition, the test of raw biogas showed no deactivation of catalyst, justifying the implementation of the developed process for real biogas without purification.

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