A research team introduces a series of iron-doped nickel catalysts (NiO/MgAl₂₋ₓFeₓO₄) that achieve efficient hydrogen generation from methane decomposition at relatively low temperatures.
The optimized catalyst, NiO/MgAlFeO₄, reached a methane conversion rate of 91.03% and a hydrogen concentration of 91.21 vol% at just 650 °C, demonstrating both strong activity and resistance to carbon deposition.
As the global demand for carbon-free energy intensifies, hydrogen stands out for its high calorific value and clean combustion. Conventional hydrogen production methods, such as methane steam reforming, suffer from high costs, complex processes, and CO₂ emissions. Methane decomposition provides a COx-free route, producing hydrogen and solid carbon, yet typically requires temperatures above 1,200 °C. Nickel-based catalysts can lower this threshold but often suffer from carbon buildup and deactivation. Previous studies explored alloying nickel with metals like Fe or Co to improve durability, but low-temperature activity and long-term stability remained unresolved. Due to these challenges, researchers sought to design a robust Ni-Fe spinel catalyst for efficient hydrogen generation at lower temperatures.
A study (DOI:10.48130/een-0025-0005) published in Energy & Environment Nexus on 30 September 2025 by Zhiqiang Sun’s team, Central South University, offers a promising pathway for sustainable hydrogen production while reducing catalyst deactivation and carbon waste.
Researchers synthesized a family of NiO/MgAl₂₋ₓFeₓO₄ (0.50 ≤ x ≤ 2.00) catalysts via a sol–gel route to tune the spinel lattice with iron and enhance catalytic methane decomposition (CMD). Comprehensive characterization established composition, structure, and redox features: ICP-OES verified increasing Fe with decreasing Al as designed; XRD showed impurity-free MgAl₂₋ₓFeₓO₄ spinels with diffraction shifts to lower angles, evidencing lattice expansion from Fe³⁺ substitution, and discernible NiO reflections whose Scherrer sizes remained small at moderate Fe levels. BET analyses revealed a gradual drop in surface area and pore volume with higher Fe, while H₂-TPR indicated that moderate Fe strengthened NiO–support interactions (peaks shifted to higher temperatures), whereas excessive Fe boosted lattice-oxygen mobility and split the reduction into dual peaks. XPS confirmed Ni²⁺ and Fe³⁺ species and showed that Fe doping increased lattice oxygen. Performance testing identified S3 (NiO/MgAlFeO₄) as optimal: in CMD at 750 °C, it delivered the highest H₂ concentration (97 vol%) with complete CH₄ conversion after 40 min, and temperature-dependent runs maintained efficient H₂ generation even at 650 °C. Mechanistically, Raman/XRD and temperature studies revealed that Fe–O and Al–O lattice distortions promote in situ Ni–Fe alloy formation, which accelerates CH₄ activation and dehydrogenation while curbing carbon deposition—the key deactivation pathway. Raman also showed highly graphitized deposited carbon on S3, benefiting oxidative removal and regeneration. Durability was demonstrated over 20 cycles of CMD and CO₂-assisted regeneration with only minor activity loss, attributed to reversible phase evolution (NiO·MgFeAlO₄ ⇄ Ni–Fe alloy + MgFe₀.₆Al₁.₄O₄ ⇄ Ni + MgFeAlO₄) that disperses Ni, limits sintering/agglomeration, and stabilizes the catalyst under high-temperature, carbon-rich conditions. Overall, controlled Fe doping optimizes metal dispersion and oxygen mobility, while synergistic FeO₆/AlO₆ distortions enable sustained, low-temperature, high-purity hydrogen production.
This research establishes a practical route toward COx-free, low-temperature hydrogen production with recyclable catalysts. By integrating methane decomposition with CO₂-assisted regeneration, the proposed NiO/MgAlFeO₄ catalyst system enables continuous hydrogen generation with minimal carbon fouling. The solid carbon byproduct can also serve as a value-added material in electronics and nanotechnology. Beyond hydrogen fuel applications, the findings offer new insights into designing spinel-supported bimetallic catalysts with enhanced resistance to sintering and carbon accumulation. This advancement could accelerate the adoption of decentralized, low-carbon hydrogen production technologies aligned with global carbon neutrality goals.
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References
DOI
10.48130/een-0025-0005
Original Source URL
https://doi.org/10.48130/een-0025-0005
Funding Information
This work was supported by the National Key R&D Program of China (2022YFE0206600).
About Energy & Environment Nexus
Energy & Environment Nexus is a multidisciplinary journal for communicating advances in the science, technology and engineering of energy, environment and their Nexus.