Efficient photoelectrochemical sensor of Cu²⁺ based on ZnO-graphene nanocomposite sensitized with hexagonal CdS by calcination method

A novel ternary nanocomposite of CdSH/ZnO-GE was prepared for photoelectrochemical (PEC) selective sensing of Cu2+. ZnO nanorods and graphene (GE) nanosheets were first decorated on Ni foam (NF) simultaneously by a facile hydrothermal method and then CdS nanoparticles were loaded on ZnO-GE arrays through simple chemical bath deposition (CBD) method and following calcination process to form hexagonal CdS (CdSH). The obtained CdSH/ZnO-GE@NF sensor was characterized by scanning electron micrographs, X-ray diffraction and X-ray photoelectron spectroscopy. The CdSH/ZnO-GE@NF electrode exhibited enhanced photoelectrical activity with a photocurrent density of 6.8 mA·cm−2 under illumination at 0.5 V vs. SCE. For the PEC detection of Cu2+, the as-prepared sensor exhibited a low detection limit of 0.03 μM and wide linear concentration rang of 0.2 μM to 1 mM with high selectivity and stability. It was successfully applied to the detection of Cu2+ in real industrial waste water and sea water, suggesting that the CdSH/ZnO-GE@NF electrode is a promising sensor to detect copper pollution in natural environments.