Ruthenium-based nanomaterials are considered to be promising electrocatalysts for HER due to their higher activity. However, the active site exposure is low, and the catalytic mass activity is low. In order to achieve the particular aims, several types of engineering, such as crystal engineering, topography engineering, heterostructures and support engineering, have been used to catalysts. Here we report RuO 2 supported on CeO 2 -NC, owing to the abundant heterostructures and the presence of oxygen vacancies, the RuO 2 /CeO 2 -NC catalyst showed outstanding HER performance (98.2 mV, 53 mV and 298 mV@100 mA cm −2 in acidic, alkaline and neutral, respectively). Moreover, RuO 2 /CeO 2 -NC also has an excellent electrocatalytic durability for 40 h. The experimental achievements show that oxygen vacancies and heterostructures could jointly enhance performance of catalyst HER.
MgH 2 is widely considered a great potential solid hydrogen storage material along with hydrogen energy and is recognized as a kind of renewable energy. However, its poor hydrogen absorption and desorption kinetics and high thermodynamic stability limit its application. In this work, CeO 2 @NC (Nano-Carbon supported CeO 2 particles) nanosphere catalysts were synthesized by a one-step hydrothermal method, and the particle size of CeO 2 was about 7 nm and MgH 2 + x wt.% CeO 2 @NC ( x = 0, 2, 4, 6, 8) composites were prepared by ball milling. It was found that the generation of oxygen vacancy defects and the multivalent environment of carbon-supported Ce can play the role of hydrogen pump and synergistically catalyze MgH 2 . Adding a carbon layer prevents nano-effect generation to a certain extent, which makes H atoms diffuse rapidly. The results show that MgH 2 + 6 wt.% CeO 2 @NC can release 5.89 wt.% H 2 in 50 min at 593 K, and MgH 2 without catalyst can only release 0.31 wt.% H 2 . As the amount of catalyst added increases, the dehydrogenation activation energy of the composite material decreases by 31.11 kJ/mol H 2 . Through density functional theory calculation, it was found that the adsorption energy of the material increased by 1.21 eV after the addition of the catalyst, and the Fermi level of the density of states of the composite increased, which accelerated the electron transfer rate. This study can help workers catalytically modify the hydrogen storage performance of MgH 2 . Introducing oxygen vacancy defects in carbon-based supported multivalent transition metal oxide catalysts gives them a unique electronic structure and excellent catalytic activity.
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