Multifunctional Ho³⁺-Doped GdPO₄ Nanophosphors with Enhanced Optical, Photocatalytic, and Dielectric Properties

In the present work, we synthesized Ho³⁺-doped GdPO₄ phosphors via a solid-state approach, produced as fine powders with important multifunctional properties. At 980 nm excitation, the samples show strong green up-conversion emission near 550 nm with the ⁵F₄/⁵S₂ → ⁵I₈ transitions of Ho³⁺ ions. UV excitation (280–300 nm) generated distinct blue-green (~460 nm) and green (~550 nm) emissions, brilliant efficient absorption, and energy transfer in the GdPO₄ lattice observed. The phosphors exhibited excellent photocatalytic efficiency, degrading ~90% of phenolphthalein in 150 min under UV-visible light, Ho³⁺-induced trap states boost charge separation, with optimal performance at pH 1 and 1.0 mol % Ho³⁺. GdPO₄:Ho³⁺ phosphors shown strong luminescence along with notable photocatalytic and dielectric properties for multifunctional applications.