Sandwich-like electrode with tungsten nitride nanosheets decorated with carbon dots as efficient electrocatalyst for oxygen reduction.

Graphical abstract Highlights • Tungsten nitride decorated with N-carbon dot are developed using a facile route. • Excellent activity and better stability was observed compare to commercial Pt/C. • Synergistic effects caused by hybrids facilitate the conductivity and mass transfer. Abstract Developing efficient and cost-effective oxygen reduction reaction (ORR) catalysts for fuel cells is quite necessary but still full of challenges. In this study, tungsten nitride nanosheets (WN NSs) decorated with nitrogen-containing carbon dots hybrid materials are developed using a facile two-step route. Specifically, a sandwich-like porous electrode, which contains a N-doped carbon layer encapsulated with uniform carbon dots (N-CDs) and a sheet-like WN for both-side formation of N-CDs, is obtained and designed as a novel type of ORR catalysts (denoted as N-CDs@WN). The N-CDs@WN hybrid shows superior catalytic activity via a four-electron pathway and demonstrates excellent stability over long periods of time and resistance to methanol. The excellent electrocatalytic properties of N-CDs@WN hybrids benefited from a hierarchical structure with large specific area, numerous active sites, and synergistic effect between CDs and WN that can facilitate the conductivity and mass transfer during the ORR process. Compared to other carbon dots-based nanocomposites, our facile synthetic route for N-CDs@WN not only presents the advantages of being relatively green, simple, and cost-effective but also is an attractive alternative for the electrocatalyst in the non-precious ORR. [ABSTRACT FROM AUTHOR]