Engineering the SrTiO3/CuO heterostructure nanocomposite by CNT for superior visible light-driven photocatalytic performance and hydrogen evolution

Abstract

In this paper, a SrTiO₃/CuO/CNT nanocomposite was synthesized through a co-precipitation to achieve better visible light photocatalytic performance. Analysis of X-ray diffraction (XRD) combined with field emission scanning electron microscopy (FESEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, and X-ray photoelectron spectroscopy (XPS) confirmed a successful integration of CuO and CNTs into the SrTiO₃ nanoparticle. The modifications resulted in a smaller particle size while narrowing the bandgap to 2.85 eV. They enhanced electric charge capabilities with lower PL intensity, increased photocurrent density, and decreased charge transfer resistance. The photocatalytic performance was evaluated for both organic pollutant degradation and hydrogen production through water splitting. The nanocomposite demonstrated complete degradation of methylene blue (MB) within 60 min, with high efficiency for other pollutants like methyl orange (MO) and rhodamine B (RhB). A study of the mechanism using scavenger methods identified the type-II charge transfer while showing superoxide radicals act as main reactive species. The nanocomposite produced hydrogen with a rate of 1495 μmol/g.h. The degradation kinetics followed a pseudo-first-order model at low concentrations and a Langmuir-Hinshelwood model at higher levels, emphasizing the role of CNTs in enhancing charge transfer and degradation efficiency. The enhanced photocatalytic activity is attributed to the synergistic effects of CuO and CNTs, promoting efficient charge separation, extended visible light absorption, and faster electron transport. Stability tests confirmed the composite's durability, retaining 91 % efficiency after four cycles.