In Situ Sol-Gel Assembly of Graphitic Carbonitride Nanosheet-Supported Colloidal Binary Metal Sulfide into Nanosandwich-Like Multifunctional 3D Macroporous Aerogel Catalysts for Asymmetric Supercapacitor and Electrocatalytic Oxygen and Hydrogen Evolution

It is challenging to develop scalable and stable multifunctional catalysts for energy storage and conversion applications. To address the above challenges, we designed 3D macroporous nanosandwich-like aerogels using an in situ sol-gel assembly for 2D g-C3N4 nanosheet-supported NiCo2S4 nanoporous aerogels. The resultant in situ method not only assembles NiCo2S4 but also 2D g-C3N4 into the sandwich-like 3D network, allowing rapid ion and electron transport. The potential of g-C3N4 and NiCo2S4 in electrochemical energy storage and electrocatalysis is promising for improving its electrochemical activities. The synthesized 3D NiCo2S4/g-C3N4 (3%) composite aerogel electrode achieved a remarkable specific capacitance value, 1083 F·g-1 at 5 mA·cm-2 current density with 87.03% cyclic stability. Furthermore, the asymmetric electrochemical supercapacitor device was fabricated with a maximum specific energy of 43 Wh·kg-1, with outstanding electrochemical stability of about 97% over 10,000 charge/discharge cycles. In addition, NiCo2S4/g-C3N4 (3%) catalysts achieved 294 and 155 mV as oxygen and hydrogen evolution reaction overpotentials, respectively, at 20 and 10 mA·cm-2 current density values. This study provides a new method for the conversion of 2D sheets and 0D colloidal network into 3D macroporous nanocomposite aerogels in multifunctional applications.