Edge/Defect-Rich, Metallic, and Oxygen-Heteroatom-Doped WS₂ Superstructure with Superior Electrocatalytic Performance for Green Solar Energy Conversion

Two-dimensional tungsten sulfide is widely applied in electrocatalysis. However, WS₂ possesses catalytic active sites located at the layer edge and an inert surface for catalysis. Therefore, increasing the exposure of active sites at the edge and effectively activating the inert sites on the surface is an important challenge. Here, an edge/defect-rich and oxygen-heteroatom-doped WS₂ (ED-O-WS₂ ) superstructure was synthesized. The power-conversion efficiency (PCE) of dye-sensitized solar cells (DSCs) based on an ED-O-WS₂ counter electrode reached 10.36 % (under 1 sun, AM 1.5, 100 mW cm^-2 ) and 11.19 % (under 40 mW cm^-2 ). These values are, to our knowledge, the highest reported efficiency for DSCs based on Pt-free counter electrodes in I₃ ^- /I^- electrolytes. Analysis of the micro/nano structure and the electrocatalytic mechanism indicate that ED-O-WS₂ exhibits metallic properties in the electrolyte, and that abundant edges and defects as well as oxygen doping in ED-O-WS₂ play an important role in improving the catalytic activity of WS₂ . Moreover, ED-O-WS₂ displays better catalytic reversibility for I₃ ^- /I^- electrolytes than Pt.