Application of a Functionalized K_1–xNi_xNbO₃ Structure: Enhancing the Photocatalytic Activity of a CdS/K_1–xNi_xNbO₃ Composite

Abstract

Herein we report a K1–xNixNbO3 composite undergoing a phase transition from orthorhombic to rhombohedral, resulting in a Ni particle and a short Nb–Oδ- on the surface caused by a structural distortion. The Ni particles are dispersed on the overall surface of the structure, and the short bonded Nb–Oδ- sticks out to the structure interstices on the surface. The properties of the structure and surface of K1–xNixNbO3 are defined by spectroscopic analysis of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman, nuclear magnetic resonance (1H NMR), and X-ray photoelectron spectroscopy (XPS). This unique surface property enables the formation of two hybrid composites that deposit CdS on either site of the Ni/Ni–H particle or short Nb–Oδ-, resulting in a different interface between CdS and K1–xNixNbO3. The one that deposits CdS on the Ni/Ni–H particles is denoted as SCdS/K1–xNixNbO3, and the other that deposits CdS on the short Nb–Oδ- is denoted as CdS/K0.9Ni0.1NbO3. SCdS/K1–xNixNbO3 exhibits a delayed kinetics for CdS photoinduced electrons compared to that of CdS/K1–xNixNbO3 as decayed fluorescence at ca. 311 ps, while indicating ca. 238 ps for CdS/K1–xNixNbO3. As a result, SCdS/K1–xNixNbO3 exhibits a superior photocatalytic activity for H2 production of ca. 3.1 mmol g–1 h–1 compared to CdS/K1–xNixNbO3 with ca. 2.7 mmol g–1 h–1.