Efficient green hydrogen generation: A synergistic Nd(OH)₃-Graphene nanohybrid catalyst for sodium borohydride methanolysis

Hydrogen (H₂) generation via catalytic hydrolysis, methanolysis, and ethanolysis of sodium borohydride (SBH) offers a promising route for clean and efficient H₂ storage and release. However, slow reaction kinetics and limited catalyst efficiency remain significant challenges. To address these issues, graphene nanoplatelets integrated into neodymium hydroxide (GNs@Nd–OH) nanohybrids with varying GNs contents were synthesized using the Pulsed Laser Ablation in Liquid (PLAL) method, ensuring uniform dispersion and strong interfacial contact. The objective of this study was to optimize the catalyst design and investigate the effects of solvent type on H₂ generation efficiency. The catalytic performance of the nanohybrids was evaluated for H₂ generation from SBH via hydrolysis (433.3 mL min⁻¹·g_cat⁻¹), methanolysis (666.7 mL min⁻¹·g_cat⁻¹), and ethanolysis (133.3 mL min⁻¹·g_cat⁻¹), the nanohybrids with the 5.66 wt% GNs exhibited the highest catalytic activity and stability. Among the three media, methanolysis showed superior H₂ yield due to enhanced reaction kinetics and reduced byproduct formation. Kinetic studies revealed an activation energy (E_a) of 26.75 kJ/mol, with corresponding entropy (ΔS) and enthalpy (ΔH) values of −110.46 J/K, and 24.34 kJ/mol, respectively, and a Gibbs free energy (ΔG) value of 57.81 kJ/mol, confirming favourable thermodynamics. Reusability tests demonstrated catalyst stability over five cycles, with negligible loss of activity. The synergistic interaction of GNs and Nd-OH promotes Nd–C/Nd-O-C routes, increases active site availability, and enhances surface oxygen vacancies, thereby improving catalytic efficiency. This work highlights that PLAL-synthesized GNs@Nd-OH nanohybrids may be cost-effective and efficient catalysts for sustainable green H₂ generation, supporting their potential for large-scale H₂-based clean energy solutions.