Bio-derived catalysts for hydrogen production: Synthesis, characterization, and performance

In this study, green synthesis method was used to prepare Co–La–B catalysts using Rheum ribes bark extract as stabilizing agent. SEM, EDX, XRD, FTIR, TEM and XPS analyses determined the structural and morphological properties of the Co–La–B catalyst. The average particle size was found to be about 30 nm, indicating a high surface area, which can enhance the catalytic activity. In addition, the presence of functional groups in the shell extract was confirmed, suggesting their role in stabilizing the metal particles during synthesis. The particle size was determined to be 20–50 nm in TEM analysis results. For the first time, green synthesis of Co–La–B catalyst using Rheum ribes bark extract was carried out and the effect of different NaOH/NaBH₄ concentrations, different amounts of catalyst and temperature on sodium borohydride hydrolysis was studied. In the study, the cycle frequency (TOF) values for Co–La–B catalyst at different temperatures were determined to be 31610 mLH₂/gcat.min. Activation energy (Ea), activation entropy (ΔS) and activation enthalpy (ΔH) values were calculated as 62.61 kJ/mol, −120 J/molK and 29.82 kJ/mol, respectively. Reusability tests determined the efficiency of the nanoparticle as 89.4 %.