Enhanced hydrogen storage in Ni/Ce composite oxides

Abstract

The properties of dried (but not calcined) coprecipitated nickel ceria systems have been investigated in terms of their hydrogen emission characteristics following activation in hydrogen. XRD and BET data obtained on the powders show similarities to calcined ceria but it is likely that the majority of the material produced by the coprecipitation process is largely of an amorphous nature. XPS data indicate very little nickel is present on the outermost surface of the particles. Nevertheless, the thermal analytical techniques (TGA, DSC and TPD-MS) indicate that the hydrogen has access to the catalyst present and the nickel is able to generate hydrogen species capable of interacting with the support. Both unactivated and activated materials show two hydrogen emission features, viz. low temperature and high temperature emissions (LTE and HTE, respectively) over the temperature range 50 and 500 degrees C. A clear effect of hydrogen interaction with the material is that the activated sample not only emits much more hydrogen than the corresponding unactivated one but also at lower temperatures. H(2) dissociation occurs on the reduced catalyst surface and the spillover mechanism transfers this active hydrogen into the ceria, possibly via the formation and migration of OH(-) species. The amount of hydrogen obtained (~0.24 wt%) is approximately 10x higher than those observed for calcined materials and would suggest that the amorphous phase plays a critical role in this process. The affiliated emissions of CO and CO(2) with that of the HTE hydrogen (and consumption of water) strongly suggests a proportion of the hydrogen emission at this point arises from the water gas shift type reaction. It has not been possible from the present data to delineate between the various hydrogen storage mechanisms reported for ceria.

Low-Temperature Dissociation of CO2 on a Ni/CeO2(111)/Ru(0001) Model Catalyst

“…It has been reported that CeO 2 improves the catalytic performance of nickel for CO 2 reforming into methane, − because it prevents coke formation − and increases the stability of Ni nanoparticles . Further benefit comes from the strong metal–support interaction between Ni and ceria, which alters the electronic and chemical properties of Ni. − In spite of numerous investigations, the mechanism of CO 2 activation over metal/ceria catalysts is still under debate at the molecular level. For instance, Bradford and Vannice described a hydrogen-assisted CO 2 activation mechanism via a carbonate intermediate in the metal–support interfacial region .…”

EIS study of nano crystalline Ni-cerium oxide coating electrodeposition mechanism

“…In recent years, Ni-CeO 2 composite coatings have been widely used as an active catalyst for partial oxidation of methane [14][15][16], hydrogen production and storage [17][18][19]. Ni-cerium oxide composite coatings also have favorable physical properties.…”

Promising hydrogen storage properties of cost-competitive La(Y)–Mg–Ca–Ni AB3-type alloys for stationary applications

“…1,2 Compared with the gas cylinders, metal hydrides have attracted lots of attention around the world due to the advantages of much higher volume density (70-150 kg m À3 ), more satisfying safety performance, much higher hydrogen purity, and much lower moderate operating conditions. [3][4][5][6][7][8][9][10][11][12] In recent years, the La-Mg-Ni based hydrogen storage alloys, especially the alloys with superlattice structures of AB 3 -, A 2 B 7and A 5 B 19 type, have been a focus of studies. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] These structures possess characteristic layered structure consisting of one MgZn 2 -type (A 2 B 4 ) cell and one to three CaCu 5 -type (AB 5 ) cells stacking along c-axis, which are considered as the promising candidates to replace current AB 5 -type alloys as negative electrodes of MH-Ni batteries.…”