Synthesis of Ni3Bi2S2 Coupled with N-Doped Carbon Sheets as Electrocatalyst for Triiodide and Oxygen Reduction

Herein, we report a novel composite structure consisting of Ni 3 Bi 2 S 2 particles coupled with N-doped carbon (NC) sheets. Different from the generally used high vacuum or microwave-assisted technologies, metal-rich Ni 3 Bi 2 S 2 can be successfully synthesized via a simple pyrolysis procedure, with NC employed as a reducing agent. In addition, the phase purity, size, and dispersity of the Ni 3 Bi 2 S 2 particles, which were encapsulated by the NC shell, were modulated by the content of NC. The X-ray photoelectron spectroscopy (XPS) analysis demonstrated the metallic state of the Ni and Bi elements, which ensured good Ni 3 Bi 2 S 2 electrical conductivity. As a result, the resultant Ni 3 Bi 2 S 2 /NC (0.55 II) catalyzed triiodide reduction with a lower charge transfer resistance than commercial Pt/C (1.4 II). Moreover, Ni 3 Bi 2 S 2 /NC catalyzed the oxygen reduction reaction with a positive ORR half-wave potential (0.81 V vs. RHE) and a low Tafel slope (47 mV dec -1 ). Our study thus provides the novel exploration of the electrochemical performance of Ni 3 Bi 2 S 2 and indicates its promising application in electrocatalytic reactions.