Achieving highly efficient hydrogen generation and uniform Ag nanoparticle preparation via hydrolysis of Mg9Ag alloy milled under hydrogen gas

•Mg9Ag alloy is employed for both hydrogen generation and Ag NPs preparation.•Hydrogen yield reaches 730 mL g−1 within 25 min at 298 K for H2-milled Mg9Ag.•Ag NPs with a size of less than 50 nm were obtained for H2-milled Mg9Ag.

A Mg9Ag alloy is employed as a medium for both production of hydrogen and preparation of Ag nanoparticles through hydrolysis. Mg9Ag milled under H2 exhibits very favorable structural characteristics, i.e., yielding a fine nanocrystal powder and partial hydrogen-induced phase decomposition. As a result, a hydrogen yield of 730 mL g−1 is obtained in 25 min at 298 K, a much higher rate than produced by samples not milled or milled under argon. Moreover, the hydrolysis by-product can be recycled to obtain Ag nanoparticles by removing insoluble Mg(OH)2 using an added HCl solution. These results show that this process provides a highly efficient method for economically produce hydrogen and Ag nanoparticles.