Synthesis of tin nanoparticles on Ketjen Black in ionic liquid and water for the hydrogen evolution reaction

Abstract

Tin nanoparticles (Sn-NPs) embedded in Ketjen Black carbon (KB) were synthesized from anhydrous tin(II) chloride by reduction with sodium borohydride in the presence of different imidazolium based ionic liquids (ILs) or water and tested towards the hydrogen evolution reaction (HER) in electrocatalytic water splitting. Transmission and scanning electron microscopy showed the formation of well distributed Sn-NPs on KB with average sizes of 49 ± 25 to 96 ± 49 nm depending on the IL or water medium. Porosity was investigated by nitrogen sorption measurements indicating the preservation of the mesoporous structure of KB with BET surface areas in the range of 276 to 568 m2 g−1 and total pore volumes of 0.38 to 0.75 cm3 g−1. The metal content of the Sn/KB composites was determined by thermogravimetric analysis to be between 31 and 46 wt%. Sn/KB synthesized in HCl/H2O showed a better performance towards HER with an overpotential of 136 mV compared to the overpotential of the other samples synthesized in IL ranging between 205 and 319 mV. Tafel analysis yielded a slope of 120 mV dec−1 and a low charge transfer resistance confirmed the good performance of Sn/KB synthesized in HCl/H2O. After stability test the sample synthesized in the IL [HO-EMIm][BF4] demonstrated an improved performance with an overpotential of 166 mV.

Keywords

• Tin nanoparticles
• Ionic liquid
• Ketjen Black
• Electrocatalysis
• Hydrogen evolution reaction