Enhanced generation of hydrogen through hydrolysis of biochar-coupled magnesium: Analysis of the performance of biochar-support and the effect of metallic coating on biochar

Abstract

Hydrolysis is regarded as a safe, efficient and adorable approach to generate hydrogen (H2) from magnesium (Mg) or Mg-based materials. In this work, biochar (BC) and ferric oxide (Fe2O3) coated biochar (magnetic biochar: MBC) were synthesized and applied along with Mg as catalysts for an enhanced H2 generation. The Mg-Xwt%Y (X = 1.0, 3.0, 5.0, 10.0, 15.0 and Y = BC, MBC) composites were prepared via ball milling and employed to investigate their hydrolysis performance through kinetics in seawater. Among employed dosages, 10.0 wt% contents exhibited the best hydrolysis performance. Mg-10.0 wt%BC and Mg-10.0 wt%MBC composites after 1 h ball milling generated 820.03 and 828.02 mL/g (conversion yields of 89.03% and 89.99%) H2 in 40 and 10 min, respectively. Further, 10.0 wt% of BC and MBC decreased the hydrolysis kinetic energy of Mg from 63.9 to 41.07 and 17.16 kJ/mol, respectively. MBC has better catalytic effects for Mg hydrolysis compared with those by BC could be due to relatively more functional groups, providing more channels for water molecules to interact with Mg resulting in subsequent enhanced hydrolysis. Hence, MBC increased the reactivity and galvanic corrosion of Mg as well as prevented the formation of passive layer of magnesium hydroxide (Mg(OH)2) on fresh surface of Mg. The performance of MBC-supported Mg in hydrolysis process is anticipated to be essential for the creation of environmentally-friendly portable H2 generators, the use of clean generation of H2 energy and the reduction of environmentally adverse emissions.