Designing and boosting the performance of advanced supercapacitor using synergistic effects of N, S, and rare earth metals @TiO2

• The development and exploration of advanced materials with high durability and superior electrochemical performance remain enduring challenges in renewable energy research. In the current study, a hydrothermal method was employed to synthesize titania-based nanomaterials, doped with metals (samarium, praseodymium), and nonmetals (nitrogen, sulfur), and thoroughly analyzed by several techniques. The XRD, Raman, and FTIR confirm the formation of the anatase phase of TiO 2 even after the addition of dopants. The synthesized nanoparticles' calculated crystallite sizes range from 16.8 to 38 nm. The red shift in the bandgap and enhanced absorption in the visible region were evaluated using UV–Vis-DRS measurements. The surface morphology, particle size, and presence of dopants in the crystal lattice of TiO 2 were confirmed by the FE-SEM, EDS, TEM, and STEM analysis. The electrochemical performance of the synthesized nanomaterials was systematically evaluated for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and supercapacitor (SCs) applications. The supercapacitance performance of these materials was studied by electroanalytical techniques such as Cyclic Voltammetry (CV), Galvanostatic Charge-discharge (GCD), and Electrochemical impedance spectroscopy (EIS). The electrochemical supercapacitor analysis demonstrated that NSPr-TiO 2 exhibits superior performance, delivering a specific capacitance of 1550 Fg -1 , with 90 % retention of its capacitance after 1000 cycles. In contrast, the NS-TiO 2 , NSSm-TiO 2 , and pristine TiO 2 exhibit specific capacitance values of 1225, 1200, and 1192.5 Fg -1. An outstanding supercapacitance performance with superior coulombic efficiency and maximum retention of capacitive performance over about 6.5 h (98 %), marks this material as a potential candidate for supercapacitance. Additionally, as-prepared NSPr-TiO 2 demonstrates excellent catalytic activity with dynamic stability towards the OER, with the smallest Tafel slopes (138 mV/dec). The Tafel slopes for pristine TiO 2 , NSSm-TiO 2, and NS-TiO 2 were found to be 146, 144, and 142 mV/dec, respectively. Furthermore, a distinct onset potential below −1.25 mV is observed for NS-TiO 2 , with further cathodic shifts noted for NSSm-TiO 2 , NSPr-TiO 2 variants, indicating improved HER activity. Nevertheless, the remarkable electrochemical activity in water splitting reactions and enhanced supercapacitive performance of these materials represent a significant advancement in the engineering of versatile, high-efficiency functional materials. The development and exploration of advanced materials with high durability and superior electrochemical performance remain enduring challenges in renewable energy research. In the current study, a hydrothermal method was employed to synthesize titania-based nanomaterials, doped with metals (samarium, praseodymium) and nonmetals (nitrogen, sulfur), and thoroughly analyzed by several techniques. The XRD, Raman, and FTIR confirm the formation of the anatase phase of TiO 2 even after the addition of dopants. The synthesized nanoparticles' calculated crystallite sizes range from 16.8 to 38 nm. The red shift in the bandgap and enhanced absorption in the visible region were evaluated using UV–Vis-DRS measurements. The surface morphology, particle size, and presence of dopants in the crystal lattice of TiO 2 were confirmed by the FE-SEM, EDS, TEM, and STEM analysis. The electrochemical performance of the synthesized nanomaterials was systematically evaluated for oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and supercapacitor (SCs) applications. The supercapacitance performance of these materials was studied by electroanalytical techniques such as Cyclic Voltammetry (CV), Galvanostatic Charge-discharge (GCD), and Electrochemical impedance spectroscopy (EIS). The electrochemical supercapacitor analysis demonstrated that NSPr-TiO 2 exhibits superior performance, delivering a specific capacitance of 1550 Fg -1 , with 90 % retention of its capacitance after 1000 cycles. In contrast, the NS-TiO 2 , NSSm-TiO 2 , and pristine TiO 2 exhibit specific capacitance values of 1225, 1200, and 1192.5 Fg -1. An outstanding supercapacitance performance with superior coulombic efficiency and maximum retention of capacitive performance over about 6.5 h (98 %) marks this material as a potential candidate for supercapacitance. Additionally, as-prepared NSPr-TiO 2 demonstrates excellent catalytic activity with dynamic stability towards the OER, with the smallest Tafel slopes (138 mV/dec). The Tafel slopes for pristine TiO 2 , NSSm-TiO 2, and NS-TiO 2 were found to be 146, 144, and 142 mV/dec, respectively. Furthermore, a distinct onset potential below -1.25 mV is observed for NS-TiO 2 , with further cathodic shifts noted for NSSm-TiO 2 , NSPr-TiO 2 variants, indicating improved HER activity. These materials show outstanding electrochemical performance, with a specific capacitance of 1550 F g⁻¹ at 1 A g⁻¹, highlighting their high efficiency and multifunctionality.