Binary CuO/TiO2 nanocomposites as high-performance catalysts for tandem hydrogenation of nitroaromatics

Synergistic interface between metal Cu nanoparticles and CoO for highly efficient hydrogen production from ammonia borane

The development of efficient non-noble metal catalysts for the dehydrogenation of hydrogen (H₂) storage materials is highly desirable to enable the global production and storage of H₂ energy. In this study, Cu _x -(CoO)_1-x /TiO₂ catalysts with a Cu-CoO interface supported on TiO₂ are shown to exhibit high catalytic efficiency for ammonia borane (NH₃BH₃) hydrolysis to generate H₂. The best catalytic activity was observed for a catalyst with a Cu : Co molar ratio of 1 : 1. The highest dehydrogenation turnover frequency (TOF) of 104.0 mol_H2 mol_metal ^-1 min^-1 was observed in 0.2 M NaOH at room temperature, surpassing most of the TOFs reported for non-noble catalysts for NH₃BH₃ hydrolysis. Detailed characterisation of the catalysts revealed electronic interactions at the Cu-CoO heterostructured interface of the catalysts. This interface provides bifunctional synergetic sites for H₂ generation, where activation and adsorption of NH₃BH₃ and H₂O are accelerated on the surface of Cu and CoO, respectively. This study details an effective method of rationally designing non-noble metal catalysts for H₂ generation via a metal and transition-metal oxide interface.

Carboxymethyl Cellulose/Copper Oxide–Titanium Oxide Based Nanocatalyst Beads for the Reduction of Organic and Inorganic Pollutants

In this work, we have developed novel beads based on carboxymethyl cellulose (CMC) encapsulated copper oxide-titanium oxide (CuO-TiO2) nanocomposite (CMC/CuO-TiO2) via Al+3 cross-linking agent. The developed CMC/CuO-TiO2 beads were applied as a promising catalyst for the catalytic reduction of organic and inorganic contaminants; nitrophenols (NP), methyl orange (MO), eosin yellow (EY) and potassium hexacyanoferrate (K3[Fe(CN)6]) in the presence of reducing agent (NaBH4). CMC/CuO-TiO2 nanocatalyst beads exhibited excellent catalytic activity in the reduction of all selected pollutants (4-NP, 2-NP, 2,6-DNP, MO, EY and K3[Fe(CN)6]). Further, the catalytic activity of beads was optimized toward 4-nitrophenol with varying its concentrations and testing different concentrations of NaBH4. Beads stability, reusability, and loss in catalytic activity were investigated using the recyclability method, in which the CMC/CuO-TiO2 nanocomposite beads were tested several times for the reduction of 4-NP. As a result, the designed CMC/CuO-TiO2 nanocomposite beads are strong, stable, and their catalytic activity has been proven.