Ternary Copper Iron Sulfide Microflowers Anchored on Reduced Graphene Oxide for Water Splitting

Transition metal sulfides are widely employed as bifunctional electrocatalysts owing to their unique structural features, well-off active sites, and modifiable electronic and mechanical properties. Herein, we have synthesized highly efficient ternary copper iron sulfide (CuFeS2)/reduced graphene oxide (rGO) composites via a hydrothermal approach for an overall water splitting process. The tetragonal structure of CuFeS2 microflowers anchored on rGO sheets is identified by using X-ray analysis and compared with standard Joint Committee on Powder Diffraction Standards (JCPDS) #35-752. In Raman spectra, the existence of two bands D (defects) and G (graphitic) confirms the presence of the rGO composite with CuFeS2, and the ratio of D and G band (ID/IG) is observed to be 1.18. The morphological analysis using scanning electron microscopy and transmission electron microscopy substantiates the formation of microflowers with rGO sheets. The elemental composition of CuFeS2/rGO was analyzed by energy-dispersive X-ray analysis, which demonstrated a weight percentage of various compositions of Cu (18.07%), Fe (11.32%), S (13.88%), and C (56.74%). Moreover, the CuFeS2/rGO composites exhibited a high surface area, pore volume, and diameter of 50.352 m2/g, 0.162 cc/g, and 2.471 nm, respectively. The fabricated electrodes were examined by using electrochemical characterization. The obtained results clearly showed low overpotential and low Tafel slope values in both the oxygen evolution reaction (OER) (176 mV and 216 mV/dec) and hydrogen evolution reaction (HER) (153 mV and 150 mV/dec) processes. In addition, the fabricated composite exhibited low 1.59 V cell voltages for an overall water splitting process with more excellent stability, and it showed a faradaic efficiency of 97.8% for H2 and 95.5% for O2. Therefore, the composite of rGO in ternary metal sulfide plays a predominant role in improving the electrocatalytic activity of the material, and the CuFeS2/rGO composite emerges as a promising electrode for the water splitting process.