Comprehensive analysis of the synthesized Zinc-doped yttrium titanate pyrochlore solid solution: Structural, vibrational, and electrochemical insights

Abstract

A novel Zinc-doped Yttrium Titanate (YTZ) solid solution with a pyrochlore structure, synthesized via a solid-state route, was investigated for its potential in hydrogen storage applications. Comprehensive characterization using various techniques confirmed the formation of a cubic crystal structure with the Fd-3m space group for compositions within the ZnO content range from x = 0 to 0.30. A subtle increase in the lattice parameter (a) was observed with increasing substitution levels (x). This increase is attributed to the substitution of Zn²⁺ on Ti⁴⁺ sites and the concomitant creation of vacancies in both the anionic and cationic sublattices, as revealed by quantitative Rietveld analysis. The YTZ solid solution exhibits semiconducting behavior with a band gap ranging from 3.10 to 3.25 eV that may contribute to its hydrogen storage properties. Notably, the YTZ_0.25 composition displayed a remarkable hydrogen storage capacity of 1200 mAh/g. This can be attributed to the presence of active redox species, favorable morphology, and the structural vacancies introduced by Zn²⁺ substitution, which facilitate hydrogen interaction. These findings position YTZ solid solution as a promising candidate for clean energy technologies, particularly in the realm of hydrogen storage.