Enhanced hydrogen production from sucrose-derived carbon quantum dots-supported Ru catalysts: A comparative study of KBH4 and NaBH4 hydrolysis

Abstract

Despite increasing interest in borohydride hydrolysis for hydrogen generation, limited studies have explored carbon quantum dots (CQDs) derived from low-cost, renewable sources such as sucrose as catalyst supports. In this study, sucrose-derived CQDs were synthesized via a green hydrothermal method and employed as a support material for Ru catalysts. A novel hydrogen potential catalytic activity (HPCA) metric was introduced to compare the performance of Ru@CQDs in the hydrolysis of sodium borohydride (SBH) and potassium borohydride (PBH), addressing the lack of normalized efficiency metrics across different hydrogen sources. The ideal conditions for each hydrolysis reaction were established based on the hydrogen generation rate (HGR) after studying various catalyst characteristics using UV–Vis, UV-PL, TEM, and FT-IR analyses. The HGR values using 4 % NaBH4 and 4 % KBH4 were 167,588 and 122,527 mL g−1 min−1, respectively. However, the hydrogen potential catalytic activity metrics (HPCA), calculated based on the hydrogen content of the sources, were 1.551,741 mL g−1 min−1 and 1.655,770 mL g−1 min−1 for NaBH4 and KBH4 hydrolysis, respectively. This indicates that the rate of hydrogen production during KBH4 hydrolysis is higher than that during NaBH4 hydrolysis. For each hydrolysis reaction, the catalyst's turnover frequency (TOF) was also determined to assess its effectiveness: 924.8 mol H2.mol. Ru−1.min−1 for NaBH4 hydrolysis and 573.3 mol H2.mol Ru−1.min−1 for KBH4 hydrolysis. Additionally, the experimental data on the kinetics and activation energy of the hydrolysis processes, as well as the catalyst's reusability, were analyzed.