# Spray-Deposited TiO2–CuO Heterostructured Thin Films for Rifampicin Degradation and Solar Cell Application

## TL;DR

This study explores TiO2–CuO thin films for degrading antibiotics and improving solar cell efficiency.

## Contribution

The novel use of spray pyrolysis to synthesize TiO2–CuO films for pharmaceutical pollutant degradation is presented.

## Key findings

- TiO2–CuO thin films achieved nearly 99% rifampicin degradation under sunlight in 3 hours.
- The 50:50 TiO2–CuO ratio (T50C50) showed optimal performance with a band gap of 1.47 eV.
- Solar cell simulations using TiO2–CuO layers reached an efficiency of about 22.5%.

## Abstract

TiO2,
CuO, and TiO2–CuO heterostructures
are commonly synthesized using hydrothermal or furnace-based methods,
which often lack precise control over the thickness of the film. Moreover,
their photocatalytic applications have mostly been limited to the
degradation of conventional dyes such as methylene blue, methyl orange,
and rhodamine B. Their use in degrading pharmaceutical pollutants
remains largely unexplored. In this study, we report the synthesis
of TiO2–CuO thin films via the spray pyrolysis method
for the photocatalytic degradation of rifampicin (RMP), a pharmaceutical
contaminant. The effects of varying the concentrations of TiO2 and CuO oxides in the sprayed solution at ratios (100:00,
75:25, 50:50, 25:75, and 0:100) on the thin films were explored and
characterized with XRD, XPS, PL, and UV–vis Spectroscopy. TiO2 and CuO exhibited band gaps of 3.4 and 1.44 eV, respectively,
while the optimized TiO2–CuO composite (T50C50)
showed a slightly increased band gap of 1.47 eV, indicating strong
interfacial coupling between the two oxides. Photoluminescence (PL)
spectra indicated all samples’ emissions in both the UV and
visible regions. The optimal ratio of TiO2 to CuO was determined
to be 50:50 (referred to as T50C50). The photocatalytic degradation
of RMP, a well-known antibiotic, under sunlight illumination demonstrated
a high degradation rate of nearly 99% after 3 h. The influence of
real operational parameters, such as pH, presence of scavengers, and
catalyst dosage, has been investigated. Furthermore, simulations of
solar cells utilizing TiO2–CuO absorber layers yielded
a promising efficiency of approximately 22.5%. These findings indicate
that TiO2–CuO heterostructured thin films have significant
potential for optoelectronic applications and photocatalytic processes.