Improved Hydrogen Generation Performance via Hydrolysis of MgH₂ with Nb₂O₅ and CeO₂ Doping

Abstract

Rapid formation of magnesium hydroxide passivation layer during hydrolysis of MgH 2 seriously blocks its application as a hydrogen generation material. MgH 2 is also susceptible to oxidation. MgH 2 with Nb 2 O 5 and/or CeO 2 doping has been prepared via high energy ball milling in this work with the aim of enhancing the hydrolysis performance and oxidation resistance. The phase compositions, microstructure and hydrogen evolution properties have been systematically investigated. Nb 2 O 5 and CeO 2 particles with particle size in the range of ³20200 nm are uniformly dotted on the surface of MgH 2 matrix after ball milling. It is found that Nb 2 O 5 shows better facilitating effects than CeO 2 on the hydrolysis performance of MgH 2 . As-milled MgH 2 +10%Nb 2 O 5 and MgH 2 +10%CeO 2 samples generate ³705 and 474 mL g ¹1 of hydrogen in distilled water within 60 min, respectively. Introducing MgCl 2 in water can also significantly enhance the hydrolysis reaction kinetics and conversion rate. As-milled MgH 2 +10%Nb 2 O 5 sample shows a hydrogen yield of 1222 mL g ¹1 in 5% MgCl 2 solution, corresponding to a conversion rate of 74.6%. However, air exposed MgH 2 +10%Nb 2 O 5 sample hardly generates any hydrogen in MgCl 2 solution. CeO 2 can modify the oxidation resistance to some extent. MgH 2 with CeO 2 doping can still produce ³250 mL g ¹1 of hydrogen after 24 h air exposure.

Facile Ball Milling Preparation of Flame-Retardant Polymer Materials: An Overview

“…Another important usage of ball milling is to conduct chemical reactions, including the simple surface modification of particles, and complicated chemical synthesis [ 14 , 55 ]. As for flame retardants, surface modification by ball milling is prominent in improving properties, such as hydrolysis resistance [ 56 , 57 ], interfacial compatibility [ 56 , 57 ], and flame-retardant efficiency [ 58 , 59 ]. Moreover, ball milling plays an important role in fabricating flame-retardant polymer composites, including simple mixing, and customizing specific structures (e.g., a segregated structure for electromagnetic wave shielding) [ 60 , 61 ].…”

Light-activated hydrolysis properties of Mg-based materials

“…Various strategies, such as the acidification of the reaction environment, 5,6 the use of salt solutions, 5,7 the modification of the morphology to obtain nanostructured hydrolysable materials, 8,9 and the incorporation of additives with different functions, 10,11 have been adopted and verified effective for activating the reaction of MgH 2 with water. However, these strategies still face many challenges, such as complex operation, high-cost or the pollution of additives.…”