Nickel-cobalt alloy oxide nanoparticles wrapped by carbon black for efficient oxygen evolution electrocatalysis.

• OER catalyst NiCoO x @CB was prepared successful through a spray-drying method. • The method is simple, environmentally friendly and easily scaled up. • NiCoO x particles exhibited average size <8 nm, offering numerous active site. • Wrapped structure could prevent active component from agglomerating during OER. • NiCoO x nanoparticles exist as an alloy oxide, promoting interatomic synergies. The search for the simple and convenient design method of a non-precious metal oxygen evolution catalyst is still an emerging strategy today. Usually, nano-alloy oxide can enhance the catalytic activity for large specific surface area and active site, which have been widely studied for the purpose of developing active electrocatalysts for water splitting, while, nanoparticles are fundamentally less stable and prone to substantial size growth in long-term operations. Therefore, a framework of hierarchical porous composite microsphere with NiCoO x nanoparticles wrapped by Carbon Black (NiCoO x @CB) was fabricated successfully through spray-drying in this paper. Benefitting from the porous nanostructure and 0 D nano-alloy oxide active site, a remarkable OER performance with a low overpotential for 241 mV at 10 mA·cm−2 in alkaline media was exhibited. And, from the support of wrapped structure, NiCoO x @CB showed a superior durability with 90 h for nanoparticles were prevented to reunion during the reaction. Also, the heterogeneous interfaces with strong charge transfers between CB and NiCoO x nanoparticles could enhance OER performance (NiCoO x showed 265 mV at 10 mA·cm−2). The proposed method in this paper work provide a facile route to construct the porous composite microsphere with excellent OER electrocatalytic activity based on non-noble metal oxide wrapped by CB. [ABSTRACT FROM AUTHOR]