This review highlights the opportunities of catalytic hydrolysis of NaBH₄ with the use of inexpensive and active Co-B catalysts among the other systems of hydrogen storage and generation based on water reactive materials. This process is important for the creation of H₂ generators required for the operation of portable compact power devices based on low-temperature proton exchange membrane fuel cells (LT PEM FC). Special attention is paid to the influence of the reaction medium on the formation of active state of Co-B catalysts and the problem of their deactivation in NaBH₄ solution stabilized by alkali. The novelty of this review consists in the discussion of basic designs of hydrogen generators based on NaBH₄ hydrolysis using cobalt catalysts and the challenges of their integration with LT PEM FC. The potential of using batch reactors in which there is no need to use aggressive alkaline NaBH₄ solutions is discussed. Solid-phase compositions or pellets based on NaBH₄ and cobalt-containing catalytic additives are proposed, the hydrogen generation from which starts immediately after the addition of water. The review made it possible to formulate the most acute problems, which require new sci-tech solutions.

This work focuses on the comparison of H₂ evolution in the hydrolysis of boron-containing hydrides (NaBH₄, NH₃BH₃, and (CH₂NH₂BH₃)₂) over the Co metal catalyst and the Co₃O₄-based catalysts. The Co₃O₄ catalysts were activated in the reaction medium, and a small amount of CuO was added to activate Co₃O₄ under the action of weaker reducers (NH₃BH₃, (CH₂NH₂BH₃)₂). The high activity of Co₃O₄ has been previously associated with its reduced states (nanosized CoB_n). The performed DFT modeling shows that activating water on the metal-like surface requires overcoming a higher energy barrier compared to hydride activation. The novelty of this study lies in its focus on understanding the impact of the remaining cobalt oxide phase. The XRD, TPR H₂, TEM, Raman, and ATR FTIR confirm the formation of oxygen vacancies in the Co₃O₄ structure in the reaction medium, which increases the amount of adsorbed water. The kinetic isotopic effect measurements in D₂O, as well as DFT modeling, reveal differences in water activation between Co and Co₃O₄-based catalysts. It can be assumed that the oxide phase serves not only as a precursor and support for the reduced nanosized cobalt active component but also as a key catalyst component that improves water activation.

Solid-state composites based on sodium borohydride (NaBH₄) were studied for applications as hydrogen generation materials. Hydrates of cobalt and nickel chlorides subjected to a thermal treatment were added to the composites as catalyst precursors. Using thermal analysis and FTIR spectroscopy, it was shown that the amount of water removed increases with the increasing temperature. Herewith, the water molecules that remained in the samples were strongly bound to the metal and isolated from each other. According to the ultraviolet–visible (UV-vis) spectroscopy data, with the increasing temperature of the thermal pretreatment there took place a substitution of a portion of water molecules by chloride ions in the nearest environment of the metal. It appeared that it was the resulting weakening of the electrostatic field on metal that was mainly responsible for the formation of a more finely dispersed catalytic phase of amorphous cobalt boride in the reaction medium under the action of sodium borohydride. The smaller particles of the active components led to a faster rate of gas generation when water was added to the solid-state NaBH₄ composites. This trend remained for both the cobalt and the nickel catalytic systems even when the activity was calculated per gram of the metal. Thus, for the preparation of solid-state NaBH₄ composites, hydrates of cobalt and nickel chlorides with a low content of water should be used.

The effect of different regimes of combustion of glycine–nitrate precursors on the formation of perovskite phases (LaMnO₃ and LaCrO₃) without additional heat treatment was studied. The following three combustion regimes were compared: the traditional solution combustion synthesis (SCS), volume combustion synthesis (VCS) using a powdered precursor, and self-propagating high-temperature synthesis (SHS) using a precursor pellet. The products of combustion were studied using a series of physicochemical methods (attenuated total reflection infrared spectroscopy (ATR FTIR), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and thermal analysis). SHS was found to be the most productive regime for the formation of perovskite because of its ability to develop high temperatures in the reaction zone, which led to a reduced content of the thermally stable lanthanum carbonate impurities and to an increased yield and crystallite size of the perovskite phase. The reasons for the better crystallinity and purity of LaCrO₃ as compared with LaMnO₃ is also discussed, namely the low temperatures of the onset of the thermolysis, the fast rate of combustion, and the favorable thermodynamics for the achievement of high temperatures in the reaction zone.

A solid-state NaBH₄/Co composite has been employed as a hydrogen-generating material, as an alternative to sodium borohydride solutions, in the long storage of hydrogen. Hydrogen generation begins in the presence of cobalt-based catalysts, immediately after water is added to a NaBH₄/Co composite, as a result of sodium borohydride hydrolysis. The hydrogen generation rate has been investigated as a function of the pressure used to press hydrogen-generating composites from a mechanical mixture of the hydride and cobalt chloride hexahydrate. The hydrogen generation rate was observed to increase with the increase of this pressure. Pre-reduction of the cobalt chloride, using a sodium borohydride solution, leveled this dependence with a two-fold decrease in the gas generation rate. According to TEM and XPS data, oxidation of the particles of the pre-reduced cobalt catalyst took place during preparation of the composites, and it is this oxidation that appears to be the main reason for its low activity in sodium borohydride hydrolysis.