Metal‐organic Framework Templated CoNi2S4 Anchored MWCNT: A Multifunctional Application for Photocatalysis, Water Splitting, and Dye-Sensitized Solar Cells

The escalating energy crisis, dependence on non-renewable energy sources, and the need for efficient elimination of hazardous chemical compounds from water underscore the pressing demand for alternative renewable energy solutions and environmental protection techniques. Solar energy has developed as a feasible clean energy source, with electrochemical water splitting and photocatalytic water purification offering promising techniques for creating clean energy and tackling environmental challenges. This research presents an innovative hybrid catalyst, designated as ZIF-67-NC@CNS/MWCNT, which consists of N-doped Zeolite Imidazolate Framework-67 (ZIF-67) derived carbon and CoNi2S4 with Multi-Walled Carbon Nanotubes (MWCNT), utilizing a Metal-Organic Framework (MOF) as a template. This distinctive structure demonstrates exceptional multifunctional electrochemical performance in many applications, including Dye-Sensitized Solar Cells (DSSCs), Oxygen Evolution Reactions (OER), Hydrogen Evolution Reactions (HER), and photocatalytic degradation of tetracycline (TC). This composite, used as a counter electrode in DSSCs, attained a power conversion efficiency (PCE) of 6.35 %, a shortcircuit current density (JSC) of 12.54 mA cm-2 and an open-circuit voltage (VOC) of 0.8 V. The observed increases may be ascribed to reduced peak-to-peak separation, lowered charge transfer resistance, shorter electron lifetimes, and greater exchange current density. The ZIF-67-NC@CNS/MWCNT composite exhibited remarkable bifunctional electrocatalytic activity, with overpotentials of 144 mV and 178 mV at 10 mA cm-2 for the OER and HER, respectively. Interestingly, the hybrid composite achieved the highest degradation efficiency of 97.56 % against TC under white light irradiation. The synergistic effect of metal sulfides and carbon materials can provide additional electron transmission paths and contact areas, leading to effective I3-reduction, reduced overpotential, and enhanced degradation efficiency. Consequently, the ZIF-67-NC@CNS/MWCNT hybrid functions as a proficient multifunctional electrocatalyst for many energy and environmental applications.