TiO2-Decorated Titanium Carbide MXene co-Doped with Nitrogen and Sulfur for Oxygen Electroreduction

Challenging electroreduction of oxygen at the cathodic section of low-temperature fuel cells (FCs) furnishes several issues for their rigorous commercialization. Because of the several concerns over employing a more reliable electrocatalyst, Pt/C, such as stability (of both Pt and carbon support), scarcity, and cost, the technology remains under development for its commercial applications. Thus, to develop an efficient electrocatalyst for the electroreduction of oxygen, we report a systematic self-decoration of TiO2 on the surface and in between layers of nitrogen (-N), sulfur (-S) co-doped MXene (Ti3C2) using a hydrothermal method followed by an annealing process. The crystallographic analysis and morphological studies of such an assembly of TiO2 on N, S-doped Ti3C2 (Ti3C2/NSCD-T) is confirmed by spectroscopic and microscopic characterization techniques. Interestingly, the optimized nanocomposite (Ti3C2/NSCD-600) shows improvement in the electroreduction of oxygen with exciting E-onset = 0.98 V against reversible hydrogen electrode (RHE) and better limiting current density (J(L)) = 3.5 mA/cm(2) in the alkaline electrolyte (0.1 M KOH) solution. Moreover, rotating ring disk electrode (RRDE) measurements were performed to understand the mechanism of electroreduction of oxygen as well as to detect the peroxide (HO2-) yield. Further, the Ti3C2/NSCD-600 catalyst demonstrates faster kinetics, which is confirmed through the Tafel slope (72 mV/dec). Most importantly, Ti3C2/NSCD-600 reveals better cycling stability up to 10,000 (10k) electrochemical cycles in 0.1 M KOH against the state-of-the-art catalyst (Pt/C). Thus, the present work demonstrates the development in the electrocatalyst toward energy generation in low-temperature FCs.

Automated summary

The study presents the development of an efficient electrocatalyst for the electroreduction of oxygen in low-temperature fuel cells by self-decoration of TiO2 on the surface and in between layers of nitrogen (-N), sulfur (-S) co-doped MXene (Ti3C2) to form Ti3C2/NSCD-600 nanocomposite. The optimized nanocomposite exhibits improved catalytic performance, faster kinetics, and better cycling stability compared to state-of-the-art catalyst (Pt/C), demonstrating potential for energy generation in low-temperature FCs.