Structural transition induced by niobium doping in layered titanium disulfide: The impact on electrocatalytic performance

Transition metal dichalcogenide layered structures have become the focus of special attention for electrochemical applications in recent years. Although various engineering strategies, including size reduction and composition manipulation, have been adopted to modulate the innate electrochemical features of these layered materials, there remains a great deal of work to satisfy the specific requirements for practical applications. In this work, we set forth to provide an insight into the impact of niobium (Nb) doping on the structural features of titanium disulfide (TiS₂). In addition, we examine the influence of Nb dopant on the inherent electrochemistry and charge transfer kinetics of TiS₂ and its implication for the hydrogen evolution, oxygen reduction and oxygen evolution reaction (HER, ORR, and OER) processes. It has been found that introducing an appropriate amount of Nb atom (>10%) results in the formation of titanium trisulfide (TiS₃) belt-like structures on the surface of TiS₂ polygonal discs. Nb doping marginally changes the inherent electroactivity of TiS₂ through introducing a small trace of reducible species. Furthermore, Nb-doped TiS₂ materials show improved electron transfer kinetics when compared to pure TiS₂, with the fastest k_obs ⁰ of 5.58 × 10⁻⁴ cm s⁻¹ toward [Fe(CN)₆]^3−/4− redox probe recorded for Ti_0.95Nb_0.05S₂. The same trend is also found in the HER activity of these materials whereby Nb-doped TiS₂ materials exhibit better performance in the electrocatalytic hydrogen evolution.