A General Strategy toward Metal Sulfide Nanoparticles Confined in a Sulfur‐Doped Ti3C2Tx MXene 3D Porous Aerogel for Efficient Ambient N2 Electroreduction

Three‐dimensional (3D) porous MXene‐based aerogel architectures have attracted great interest for many applications, despite limits in renewable energy conversion owing to the lack of multifunctionality in their components. Herein, a simple and general strategy for constructing a novel functional 3D MXene‐based composite heterojunction aerogel (MS@S‐MAs) is presented via divalent metal‐ion assembly and subsequent thermal sulfidation, and its application in electrochemical nitrogen reduction reaction (NRR) is studied. The as‐prepared MS@S‐MAs comprises metal sulfide nanoparticles uniformly confined in 3D interconnected conductive S‐doped MXene sheets with intimate interfacial interaction. Benefiting from the unique properties and an interfacial interaction, MS@S‐MAs exhibit significantly improved NRR catalytic performance and excellent stability because of the higher exposure of electrochemically active sites coupled with easier accessibility, faster mass diffusion, and quicker carrier transport at the interface. Remarkably, CoS@S‐MAs show an NH3 yield rate and a Faradaic efficiency of 12.4 µg h−1 mg−1cat and 27.05% at the lower potential of −0.15 V versus a reversible hydrogen electrode in 0.1 m Na2SO4 solution under ambient conditions, which rivals or exceeds most of the previously reported MXene‐based and Co‐based catalysts. This work will open avenues to construct 3D MXene‐based materials with rich functionalities for energy storage and conversion, catalysis, and other applications. A novel 3D porous composite heterojunction aerogel is developed, in which metal sulfide nanoparticles are confined in S‐doped MXene sheets with interfacial interaction. Benefiting from the unique 3D conductive framework and intimate interfacial interaction, it shows excellent electrochemical performance and superior long‐term stability for ambient electroreduction of nitrogen to ammonia.