Structural engineering of ruthenium decorated zeolitic imidazole framework nanocomposite for hydrogen evolution reactions and supercapacitors

The advancement of renewable energy and energy storage materials as well as high energy density materials for futuristic high-value-added applications, is in high demand. In this regard, zeolitic imidazole framework (ZIF) is considered a promising water splitting and energy storage materials on account of its higher surface area and electroactive inorganic centers. Herein, ruthenium (Ru) decorated ZIF-8 and ZIF-67 nanocomposites were successfully synthesized via a simplistic strategy and subsequently employed in the hydrogen evolution reaction (HER) and supercapacitors (SCs). Compared to the congeners, the Ru/ZIF-67 nanocomposite offers a larger specific surface area, fast electron, and ion transfer, and good structural stability, which all are favorable for enhancing the overall HER and SC performance. In the HER measurements, the Ru/ZIF-67 nanocomposite exhibited a low overpotential (95 mV@10 mA/cm2) and low Tafel slope (61 mV/dec) in basic media compared to that of ZIF-8, ZIF-67, and Ru/ZIF-8. To extend the utility of the nanocomposite, high-performance symmetric supercapacitors (SSCs) were designed by employing the optimized Ru/ZIF-8 and Ru/ZIF-67 nanocomposites. Due to its larger potential window and good cycling stability, the Ru/ZIF-67 SSC device displayed two-fold higher performance with a Cs of 278 F/g, remarkable energy density of 68 Wh/kg at a power density of 1260 W/kg with a capacity retention of 92 % after 7000 charge-discharge cycles compared to the Ru/ZIF-8 SSC device. The enhanced performance of the proposed optimized nanocomposite can also be attributed to the electronic interaction between the Ru atoms and ZIF surface, which enhances the water activation and energy storage capability.