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Developing low-cost and highly active hydrolysis catalytic materials for the dehydrogenation of hydrogen-rich chemicals is a promising strategy to store and easily release hydrogen for fuel cell applications. In this study, new bimetallic hybrid nanoplates containing Co3O4 and CuCoO2 were developed via a facile and low-cost approach for catalytically producing hydrogen from ammonia borane (NH3BH3). The as-prepared efficient Co3O4–CuCoO2 material was employed as a catalyst for NH3BH3 hydrolysis, and it exhibited a high catalytic performance with a turnover frequency (TOF) of 65.0 molhydrogen molcat.−1 min−1 at room temperature. The results revealed that the hybrid Co3O4–CuCoO2 catalysts exhibited much improved catalytic activity towards the hydrolysis reaction in contrast to the individual Co3O4 and CuCoO2 catalysts. A kinetic study showed that the Co3O4–CuCoO2 catalytic material had superior activity with an apparent activation energy (Ea) of 20.5 kJ mol−1, which was found to be one of the lowest Ea for NH3BH3 hydrolysis ever reported in the literature. This work provides a promising approach for the synthesis of noble metal-free catalysts exhibiting high catalytic activity towards NH3BH3 hydrolysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • High performing hollow CuO-NiCo 2 O 4 catalysts for NH 3 BH 3 methanolysis were prepared. • TOF for the hollow CuO-NiCo 2 O 4 in NH 3 BH 3 methanolysis is up to 23.2 min−1. • The Co center in CuO-NiCo 2 O 4 is recognized as active sites by DFT calculations. • Synergistic effect between CuO and NiCo 2 O 4 results from the electrons migration. Rational construction of cost-efficient catalysts with high activity and durability for hydrogen production from ammonia borane (AB) methanolysis is highly desirable but remains a substantial challenge. In this work, we constructed a series of non-noble-metal based hollow CuO-NiCo 2 O 4 nanospheres composite, in which the CuO-NiCo 2 O 4 -0.8 nanospheres exhibit robust catalytic activity with a high turnover frequency (TOF) of 23.2 mol H2 mol cat. −1 min−1 towards AB methanolysis. Systemic experimental and computational studies reveal the promotion of activity results from the synergistic effect between CuO and NiCo 2 O 4. It is revealed the combination of CuO with NiCo 2 O 4 caused the electrons migration among Cu, Ni and Co sites and the change of d-band centers of catalyst, thus enhancing the adsorption process of CH 3 OH and AB molecules on catalyst and subsequently promoting the catalytic activity. Moreover, the Co center in CuO-NiCo 2 O 4 composite is recognized as active sites by DFT calculations. Mechanistically, the rate determining step is the dissociation of O H bond in CH 3 OH, which is confirmed by kinetic isotopic effect experiment. A plausible mechanism of methanolytic dehydrogenation of AB on CuO-NiCo 2 O 4 was proposed based on experiment and DFT calculations. These findings should shed light on the rational construction of cost-efficient catalysts with high performance for hydrogen production from AB methanolysis. [ABSTRACT FROM AUTHOR]

Construction of high-efficiency and affordable catalysts for hydrogen production from hydrolysis of ammonia borane is highly desirable, but significant challenges still exist. In this study, a series of ball-in-ball hollow structured CuO-Co 3 O 4 nanocomposites with varied Cu/Co molar ratio were constructed via simple solvothermal method combined with a post-calcination. The CuO-Co 3 O 4 composite featuring a Cu/Co molar ratio of 1: 2 displayed the highest catalytic efficiency, achieving a turnover frequency (TOF) value of 25.0 mol H2 mol cat. −1 min−1 for AB hydrolysis. An evident synergistic enhancement in catalytic activity was confirmed between CuO and Co 3 O 4. Experimental and theoretical researches uncovered that the enhancement of activity is originated from the electron transfer between Cu and Co ingredients, which is beneficial for the adsorption and activation of H 2 O and ammonia borane. In addition, the DFT calculations results revealed that the actual active sites for AB hydrolysis in CuO-Co 3 O 4 composite catalyst is the Co site. These findings should provide some insightful recommendations for designing robust and cost-effective composite catalysts for the hydrolytic dehydrogenation of ammonia borane. [Display omitted] • Ball-in-ball hollow structured CuO-Co 3 O 4 was prepared by a simple method. • Hydrolysis of ammonia borane catalyzed by the CuO-Co 3 O 4 was investigated. • The enhanced activity is rooted in the electrons flow between Cu and Co ingredients. • Actual active sites for AB hydrolysis in CuO-Co 3 O 4 were confirmed as the Co site. [ABSTRACT FROM AUTHOR]