Controllable synthesis of two-dimensional tungsten nitride nanosheets as electrocatalysts for oxygen reduction reaction

A facile synthetic strategy was developed for in-situ preparation of two-dimensional (2D) highly crystalline tungsten nitride (WN) nanosheets with controllable morphology as oxygen reduction reaction (ORR) catalysts. The dependence of the crystal structure and morphology ofWN on K2SO4 content, pH, and pyrolysis temperature was thoroughly examined. The electrocatalytic performance of WN toward ORR in an alkaline electrolyte indicated that K+ plays an important role in the control of size and shape in the hydrothermal and nitridation process, thereby promoting the formation of plate-like WO3 and 2D WN nanosheets. The WN nanosheets, with largely exposed edge sites, provide abundant catalytic active sites and allow fast charge transfer. Furthermore, they exhibit high stability for ORR and methanol tolerance.