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<p>Sustainable and cost-effective catalytic systems are essential for the environmental viability of hydrogen energy technologies. This study addresses this challenge by designing a series of non-noble Ni<sub>1−x</sub>Co<sub>x</sub>Fe<sub>2</sub>O<sub>4</sub> (x = 0–1) spinel nano catalysts via an energy-efficient sol-gel route for hydrogen production through sodium borohydride (NaBH<sub>4</sub>) methanolysis. Structural and spectroscopic characterization by XRD, SEM/EDS, FTIR, and Raman confirmed the formation of phase-pure cubic spinels across the entire composition range. Rietveld refinement revealed a systematic lattice contraction with increasing Ni<sup>2+</sup> content, consistent with Vegard’s law, while vibrational analyses evidenced cation redistribution within the Fd-3&#xa0;m spinel framework. Catalytic screening identified Ni0.75Co0.25Fe2O4 as the optimal composition, delivering a high hydrogen generation rate of 31 699 mL·min− 1·gcat−1 under mild conditions. This superior activity is attributed to a strong Ni/Co synergistic effect, reflected in a low apparent activation energy of 14.49 kJ·mol− 1. Kinetic evaluation using the Eyring approach yielded activation parameters (ΔH = 11.85 kJ·mol− 1, ΔS = -199.81 J·mol− 1·K− 1), indicating an associative surface reaction mechanism. Temperature-programmed analyses (H2-TPR, O2-TPO, NH3-TPD) further showed that the optimal catalyst possesses accessible redox couples and a favourable distribution of acid sites, lowering energetic barriers for BH₄⁻ activation. The catalyst demonstrated excellent durability, retaining 96% of its initial activity over five consecutive cycles. This work establishes Ni<sub>0.75</sub>Co<sub>0.25</sub>Fe<sub>2</sub>O<sub>4</sub> as a high-performance, sustainable, and reusable catalyst for chemical hydrogen storage, aligning with green chemistry principles and contributing to environmentally benign energy solutions.</p>

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Non-noble metal catalysis for environmental benign energy: Ni-Co nanoferrites for high-rate hydrogen generation

  • 期刊论文

  • 发表日期：

    2026年6月23日

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  • Fatima Zohra Benkrifa,
  • Fatiha Abdelmalek,
  • Khelifa Sabri,
  • Aykut Caglar,
  • Hilal Kivrak,
  • Ahmed Addou

摘要

Sustainable and cost-effective catalytic systems are essential for the environmental viability of hydrogen energy technologies. This study addresses this challenge by designing a series of non-noble Ni1−xCoxFe2O4 (x = 0–1) spinel nano catalysts via an energy-efficient sol-gel route for hydrogen production through sodium borohydride (NaBH4) methanolysis. Structural and spectroscopic characterization by XRD, SEM/EDS, FTIR, and Raman confirmed the formation of phase-pure cubic spinels across the entire composition range. Rietveld refinement revealed a systematic lattice contraction with increasing Ni2+ content, consistent with Vegard’s law, while vibrational analyses evidenced cation redistribution within the Fd-3 m spinel framework. Catalytic screening identified Ni0.75Co0.25Fe2O4 as the optimal composition, delivering a high hydrogen generation rate of 31 699 mL·min− 1·gcat−1 under mild conditions. This superior activity is attributed to a strong Ni/Co synergistic effect, reflected in a low apparent activation energy of 14.49 kJ·mol− 1. Kinetic evaluation using the Eyring approach yielded activation parameters (ΔH = 11.85 kJ·mol− 1, ΔS = -199.81 J·mol− 1·K− 1), indicating an associative surface reaction mechanism. Temperature-programmed analyses (H2-TPR, O2-TPO, NH3-TPD) further showed that the optimal catalyst possesses accessible redox couples and a favourable distribution of acid sites, lowering energetic barriers for BH₄⁻ activation. The catalyst demonstrated excellent durability, retaining 96% of its initial activity over five consecutive cycles. This work establishes Ni0.75Co0.25Fe2O4 as a high-performance, sustainable, and reusable catalyst for chemical hydrogen storage, aligning with green chemistry principles and contributing to environmentally benign energy solutions.