Dergiler / Bor Dergisi / 2018 / Cilt: 3 - Sayı: 1
Synthesis of Fe-Fe2B catalysts via solvothermal route for hydrogen generation by hydrolysis of NaBH4
- Dergi
- Bor Dergisi
- Sayfa
- 51–62
- DOI
- —
Abstract
In this study, iron sulfate (FeSO4) and sodium borohydride (NaBH4) were used tosynthesize Fe-Fe2B nanocrystals via the solvothermal route. Synthesis of Fe-Fe2Bnanocrystals was carried out under Argon (Ar) gas atmosphere with aqueoussolutions of FeSO4.7H2O and NaBH4 at various concentrations and reaction time. Thephases and microstructures of nanocrystals thus formed were characterized by X-Raydiffraction (XRD) spectroscopy and scanning electron microscopy (SEM). Surfaceareas of nanocrystals were measured by a surface area and pore-size analyzer usingnitrogen adsorption-desorption method together with Brunauer-Emmett-Teller (BET)equation. The vacuum dried nanoparticles were calcined under both Ar and air at 500ºC. Nano-cylindrical structures of Fe-Fe2B were observed when calcinated under Aratmosphere; whereas more irregular shaped particles were noticed when calcinatedunder air. The surface areas of Fe-Fe2B were determined as 12 m2/g, 5.5 m2/g and16.5 m2/g, for vacuum dried, Ar-calcined and O2-calcined products respectively.The catalytic effect of those nano-particles to generate hydrogen was studied bydetermining reaction rate of decomposition of NaBH4 in aqueous alkaline solution.The catalytic activity was investigated by systematic variation of three parameters (1)the amount of Fe-Fe2B, (2) the concentration of NaBH4 and (3) the concentration ofNaOH. The effect of temperature on the catalytic activity was also studied separatelyfor the most effective composition by varying the temperature from 25 to 70 °C. Itwas noticed that the catalytic activity of vacuum dried nanocrystals was the highest.The catalytic activity was found to increase with the increase in NaBH4 concentrationand decrease with the increase in NaOH concentration. The influence of temperaturestudied with 0.01 g of Fe-Fe2B in 1 % w/w NaBH4 solution showed that the rateof hydrogen generation could be increased almost 5 times more by varying thetemperature from 25 °C to 70 °C.