DUAL-ROUTE SYNTHESIS OF ND³⁺-DOPED MOO₃ NANOSTRUCTURES: UNVEILING PHOTOSENSING AND ANTIOXIDANT POTENTIAL

Abstract

Doped nanoparticles of MoO₃ with 1%, 2%, and 3% of Nd³⁺ were prepared at low temperature prepared through sol-gel (powder) or by thin-film (spin coated) method, using the precursor of ammonium heptamolybdate/NdCl₃·6H₂O and characterized for structural, morphological and dual (photosensing–antioxidant) functional properties. The XRD of the 2% composition showed that the sol-gel synthesized material was highly crystalline with an orthorhombic α-MoO₃ phase, while the thin film was less crystalline and presented with a more hexagonal trend without any secondary phases belonging to the Nd2O3 system. Both samples contained oxygen vacancies, confirming the presence of Nd³⁺ oxidation states that arose through the substitution of Nd with oxygen vacancies (OVM), as the direct evidence comes from the O 1s spectra with a resolvable oxygen-vacancy component between 531.3–531.6 eV. The Raman spectrum exhibited a terminal Mo=O stretching mode redshift to 938–948 cm⁻¹ in the sol-gel powder, and a defect-related spectral envelope, which grew with doping level (1855–1962 cm⁻¹) were reported. A defect-related spectral envelope (1855–1962 cm⁻¹), which increased with doping level, was reported along with a redshift of the terminal Mo=O stretching mode (to 938–948 cm⁻¹) for the sol-gel powder. FESEM showed that synthesized materials were fine nanofibrous/nanoparticulate where the microplatelet structures present in the materials are seen to coarse grain to irregular agglomerates in the films as the proportion of Nd³⁺ was increased. Functionally, photoresponse increased with doping, higher at 3% Nd (509% (sol-gel) and 617% (thin film)), while concurrently DPPH radical scavenging IC₅₀ decreased with doping to 423 µg/mL (sol-gel) and 379 µg/mL (thin film), with the thin film route showing greater effectiveness than the sol-gel powder at all doping concentrations used. The defect-driven and correlated enhancements make 3% Nd-doped MoO₃ thin films the ideal composition—making for a promising mixed-optoelectronic-antioxidant nanomaterial potential in the case of Nd2O3–MoO₃.