Electrospun metal and metal alloy decorated TiO2 nanofiber photocatalysts for hydrogen generation

Abstract

Photocatalytic nanofibers of TiO₂ decorated with 2% metal (Pt, Pd, and Cu) and metal alloys (Pt₂Pd and PtCu) were synthesized by the polymer-assisted electrospinning method, followed by microwave-assisted ethylene glycol reduction. Structurally, nanofibers calcined at 500 °C adopted an anatase phase along with a remnant rutile phase. Morphological, structural, and photocatalytic studies were carried out using scanning and transmission electron microscopy equipped with an energy dispersive spectroscopy attachment, X-ray powder diffraction, X-ray photoelectron spectroscopy, and photocatalytic hydrogen generation under UV-Vis irradiation. The calcined nanofibers were found to have a diameter of 60.0 ± 5.0 nm and length of up to several microns. High resolution TEM imaging suggests that the nanofibers are composed of agglomerated individual TiO₂ nanoparticles, which are tightly packed and stacked along the axial direction of the nanofibers. PXRD studies suggest alloy formation, as evident from peak shifting towards higher two-theta values. Surface modification with co-catalysts is shown to contribute considerably to the rate of photocatalytic H₂ generation. The amount of H₂ generated gradually increases as a function of time. The 2%Pt₂Pd/TiO₂ catalyst shows the highest rate of H₂ generation (4 mmol h⁻¹ gram_catalyst), even higher than that of 2%Pt/TiO₂ nanofiber photocatalyst (2.3 mmol h⁻¹ gram_catalyst), while 2%Cu/TiO₂ nanofiber photocatalyst shows the least activity among the decorated catalysts (0.04 mmol h⁻¹ gram_catalyst).