2D/2D/2D Metallic 1T Phase WS 2 /TiO 2 /Ti 3 C 2 T x MXene Ternary Composite for Synergistically Enhanced N 2 Electroreduction

Electrocatalytic N 2 reduction reaction is considered as an eco‐friendly and green method to synthesize ammonia (NH 3 ). However, achieving capacity‐efficient NH 3 and Faraday efficiency (FE) under environmental conditions is still very challenging. Herein, 2D TiO 2 nanosheets were in situ grown on 2D Ti 3 C 2 T x MXene with excellent conductivity (TiO 2 /Ti 3 C 2 T x MXene), and then 2D metallic 1T phase WS 2 was uniformly distributed on TiO 2 /Ti 3 C 2 T x MXene to form 2D/2D/2D ternary 1T‐WS 2 /TiO 2 /Ti 3 C 2 T x MXene heterostructures by hydrothermal process. The constructed 1T‐WS 2 /TiO 2 /Ti 3 C 2 T x MXene composites with dual active sites (Ti 3 C 2 T x MXene and 1T‐WS 2 ) exhibit a prominent NH 3 yield of 46.27 μg h −1 mg −1 cat. at −0.8 V versus RHE and a superior FE of 69.26% at −0.65 V versus RHE, and present a good electrochemical stability. 15 N isotope labeling experiment confirms that the N in the as‐synthesized NH 3 is derived exclusively via the electrocatalytic N 2 reduction over 1T‐WS 2 /TiO 2 /T i3 C 2 T x MXene composites. In situ Fourier transform infrared (FT‐IR) spectroscopy capture intermediate dynamic changes, offering direct evidence for N 2 adsorption, activation and stepwise hydrogenation on the electrocatalyst surface. Density functional theory (DFT) computations demonstrate prominent electron accumulation at the heterointerface of the ternary composite, and the reduction pathway of N 2 is mainly the alternating pathway.