Preparing non-volatile resistive switching memories by tuning the content of Au@air@TiO2-h yolk-shell microspheres in a poly(3-hexylthiophene) layer

A Simple and Scalable Route to Synthesize Cox Cu1- x Co2 O4 @Coy Cu1- y Co2 O4 Yolk-Shell Microspheres, A High-Performance Catalyst to Hydrolyze Ammonia Borane for Hydrogen Production

Yolk-shell structured micro/nano-sized materials have broad and important applications in different areas due to their unique spatial configurations. In this study, yolk-shell structured Co₃ O₄ @Co₃ O₄ is prepared using a simple and scalable hydrothermal reaction, followed by a calcination process. Then, Co_x Cu_{1- x} Co₂ O₄ @Co_y Cu_{1- y} Co₂ O₄ microspheres are synthesized via adsorption and calcination processes using the as-prepared Co₃ O₄ @Co₃ O₄ as the precursor. A possible formation mechanism of the yolk-shell structures is proposed based on the characterization results, which is different from those of yolk-shell structures in previous study. For the first time, the catalytic activity of yolk-shell structured catalysts in ammonia borane (AB) hydrolysis is studied. It is discovered that the yolk-shell structured Co_x Cu_{1- x} Co₂ O₄ @Co_y Cu_{1- y} Co₂ O₄ microspheres exhibit high performance with a turnover frequency (TOF) of 81.8 mol_hydrogen min^-1 mol_cat ^-1 . This is one of the highest TOF values reported for a noble-metal-free catalyst in the literature. Additionally, the yolk-shell structured Co_x Cu_{1- x} Co₂ O₄ @Co_y Cu_{1- y} Co₂ O₄ microspheres are highly stable and reusable. These yolk-shell structured Co_x Cu_{1- x} Co₂ O₄ @Co_y Cu_{1- y} Co₂ O₄ microsphere is a promising catalyst candidate in AB hydrolysis considering the excellent catalytic behavior and low cost.