ZIF-derived porous carbon composites coated on NiCo₂S₄ nanotubes array toward efficient water splitting

It is highly desired but challenging to grow self-supporting zeolitic imidazolate framework (ZIF) derived carbon hybrids with well-aligned superstructures for various electrocatalytic applications. In this work, we present the controlled synthesis of ZIF-based carbon hybrid arrays using self-supporting NiCo₂S₄ nanotube arrays as self-sacrificing templates. Different from other reported carbon coated NiCo₂S₄ arrays with solid surfaces, the obtained NiCo₂S₄@NiCo/N-doped porous carbon array (NiCo₂S₄@NiCoNC/CC) have well-developed porous hollow structure and ultrafine NiCo nannoparticles deposited on the surface, which can provide facilitated channels and sufficient active sites for water electrolysis. The NiCo₂S₄@NiCoNC/CC exhibits superior catalytic performance for both hydrogen evolution reaction and oxygen evolution reaction with high efficiency in alkaline solution, achieving small overpotentials of 81 and 280 mV at the current density of 10 mA cm^-2, respectively. Moreover, the NiCo₂S₄@NiCoNC/CC electrode shows excellent stability over 16 h of operation due to the robust structure of the electrode. The proposed strategy is highly promising for the rational design of well-aligned ZIF derived carbon hybrid arrays with desired morphology and composition on various substrates towards various electrocatalytic fields.