## 3 Results and Discussion  
Figure 1 represents diffraction patterns of the copper-cobalt sulfide anchored on the Ni-foam in different solvents, i.e., CCS-EG and CCS-glycerol. X-ray diffraction was measured at room temperature between 20 angle 10 to 80\({}^{\circ}\). Diffraction patterns of the Ni-foam dominate over the crystal planes from the copper-cobalt sulfide. Highly intense patterns at 20 angles 44.8\({}^{\circ}\) (111), 52.2\({}^{\circ}\) (200), and 76.8\({}^{\circ}\) (220) assigned by # symbol reflect the cubic crystal phase of the Ni-foams, with assigned planes as shown in bracket, respectively [1; 4; 18]. Furthermore, four low-intense crystal patterns as compared with the intensity of substrate crystal planes can be noticed which are centered at 31.2\({}^{\circ}\), 38.2\({}^{\circ}\), 49.9\({}^{\circ}\), and 55.1\({}^{\circ}\), respectively. Those peaks  
speak to the formation of the cubic crystalline phase of the Cu-Co-based bimetallic sulfide with space group Fd-3m without any contaminants. These four are the most intense among all diffraction patterns of the CuCo\({}_{2}\)S\({}_{4}\) system, which are assigned to the (113), (004), (115), (044) crystal planes according to the JCPDS # 042-1450 [6; 16]. Lattice parameters of this cubic system are a = b = c = 9.4740 A, and the volume of a unit cell is V = 850.35 A\({}^{3}\). The majority of the lower intense planes of this system are invisible and remain underneath in front of the dominant intensity of crystal planes arising from Ni-foam. Interestingly, no traces of any change in the diffraction patterns were rectified among the two samples fabricated in a different solvent. Survey XPS spectra of the Cu-Co-based bimetallic sulfide prepared using solvent water and glycerol are demonstrated in Figure 2a. Well-established peaks of the encompassed elements, i.e., Cu, Co, and S, along with peaks of O and C, can be recognized through this spectrum. The emergence of peaks of C and O relate to air exposure of the sample during synthesis and /or measurements [7]. The in-detail emission spectrum of Cu 2p explicates two well-distinguished peaks of the spin orbitals Cu 2p\({}_{3/2}\) and Cu 2p\({}_{1/2}\), positioned at binding energies 935.3 eV and 952.4 eV, respectively. As shown in Figure 2b, each of these peaks elaborates two well-developed illustrious states of the Cu 2p, i.e., Cu\({}^{+}\) and Cu\({}^{2+}\). Spectrum-indicating Cu\({}^{+}\) species were centered at 931.9 eV for Cu 2p\({}_{3/2}\) orbital and 952.2 eV for Cu 2p\({}_{1/2}\)[10]. Another characteristic spectrum associated with the Cu\({}^{2+}\) oxidation state was located at a binding energy of 933.6 eV and 954.6 eV inside 2p\({}_{3/2}\) and 2p\({}_{1/2}\) spin orbitals, respectively [6; 7; 21]. The emissions originating at 941.9 eV and 961.9 eV, next to the 2p\({}_{3/2}\) and 2p\({}_{1/2}\) spin orbital, respectively, are the shake-up satellites [22]. Two well-defined satellite peaks are attributed to the strong interaction between Cu cations and S anions; this also confirms intense ligand-metal charge transfer (LMCT) [7; 23]. Furthermore, the emission spectrum of the Co 2p element also bifurcates in two spin orbitals, Co 2p\({}_{3/2}\) and Co 2p\({}_{1/2}\), located at binding energies 781.5 eV and 797.10 eV, as represented in Figure 2c. Moreover, satellite emissions were found to be situated at 786.05 eV and 803.2 eV for both spin orbitals, respectively. Gaussian fitting confirms that each orbit has two species of Co cations viz Co\({}^{3+}\) and Co\({}^{2+}\). Co\({}^{2+}\), and Co\({}^{3+}\) species were centered at 780.8 eV and 782.1 eV in  
Figure 1: X-ray diffraction pattern of CuCo\({}_{2}\)S\({}_{4}\) electrodes on Ni-foam by using different solvents. the case of the 2p\({}_{3/2}\) orbit, whereas in the 2p\({}_{1/2}\) orbit, these species were found at 796.8 eV and 798.5 eV. The existence of the sulfur ions with the S\({}^{2-}\) state was confirmed from the S2p fitting, as shown in Figure 2d.