Efficient regeneration of sodium borohydride via ball milling dihydrate sodium metaborate with magnesium and magnesium silicide

The application of NaBH 4 hydrolysis to hydrogen generation is currently obstructed by its regeneration. Finding a simple and low cost method to regenerate its hydrolysis byproduct is therefore important. Herein, the regeneration of NaBH 4 is obtained by reacting its direct hydrolysis byproduct, NaBO 2 ·2H 2 O, with a mixture of Mg and Mg 2 Si by ball milling. In this reaction, the reduced agents are only metal and intermetallic compounds , thus hydrogen in the regenerated NaBH 4 (H δ− ) derives solely from NaBO 2 ·2H 2 O (H δ+ ). The introduction of Mg 2 Si increases the NaBH 4 regeneration yield to 86%, which is the highest regeneration yield reported for NaBH 4 until now. The reaction mechanism was also clarified for the first time.