Formation of a Tubular Assembly by Ultrathin Ti0.8Co0.2N Nanosheets as Efficient Oxygen Reduction Electrocatalysts for Hydrogen-/Metal-Air Fuel Cells

Highly stable and efficient oxygen electrocatalyst with low cost is of prime significance for fuel cells. Herein, we report hierarchical tubular assembly of metal nitride nanosheets via a facile hydrothermal method followed by nitridizing titanium-based dioxides. The resultant Ti0.8C0.2N nanosheets assembly demonstrates considerable oxygen reduction activities in both acidic H-2-air and alkaline Zn-air fuel cells. We intend to ascribe the high performance to the integration of modified electronic effect caused by the doping of cobalt, the high surface area and unique mesoporous structure induced by its nanosheet assemblies, and inherent structural stability of interlaced nitride nanosheets. This work offers an effective approach for rational design and scalable preparation of binary nitride nanostructures as well as a stable and efficient alternative electrocatalyst that represents a key step toward low-cost catalysis and energy conversion.