Hydrogen production from ammonia decomposition over Ni/CeO_(2) catalyst:Effect of CeO_(2) morphology

Ammonia(NH_(3)) decomposition to release CO_x-free hydrogen(H_(2)) over non-noble catalysts has gained increasing attention.In this study,three nanostructured CeO_(2) with different morphologies,viz.rod(R).sphere(Sph),and spindle(Spi),were fabricated and served as supports for Ni/CeO_(2) catalyst.The CeO_(2)supports are different in particle sizes,specific surface area and porosity,resulting in the formation of Ni nanoparticles with distinguished sizes and dispersions.The surface properties of the Ni/CeO_(2) catalysts are not only distinct but also influential,affecting the adsorption and desorption of NH_(3),N_(2),and/or H_(2)molecules.The Ni/CeO_(2)-R catalyst shows superior catalytic activity compared to the other two,owing to its smaller Ni crystallite size and larger BET surface area.The most abundant strong basic sites are observed for Ni/CeO_(2)-Spi catalyst based on its exposed CeO_(2)(110) planes,which facilitates the donation of electrons to the Ni particles,benefiting the associative desorption of N atoms.Thus,Ni/CeO_(2)-Spi shows higher catalytic activity than Ni/CeO_(2)-Sph,despite their almost identical Ni crystallite sizes.

Facile Synthesis and High-Value Utilization of Ammonia

Ammonia is a key component in fertilizer and the carbon-free hydrogen carrier.Catalytic ammonia synthesis and utilization have played a central role in the development of chemical engineering.The industrial production of ammonia remains dependent on the energy-and carbon-intensive Haber-Bosch process.A major effort has been devoted to developing robust and efficient catalysts,as well as alternative benign processes.Herein,we detail our endeavors that develop the ammonia synthesis and decomposition catalysts,and utilize the ammonia energy.We firstly discuss the catalysts for ammonia synthesis via dissociative and associative process,and the regulation of catalysts'properties.Then,we review the burgeoning electrocata-lytic nitrogen reduction process,focusing on the enhanced catalytic performances by the regulation of the catalysts and the electrode.Additionally,we provide a novel high-value utilization of ammonia to achieve the"zero-carbon"circular economy.The promising catalysts,reactors,and ammonia energy systems have been discussed in detail.We end this Account that offers future research directions and prospects of ammonia.