CuCo2O4 mixed metal oxide/TiO2 nanotube arrays hetero-nanostructure with enhanced photoelectrocatalytic activity toward galantamine

Abstract

In this research, we aim to design a simple and effective photoelectrochemical (PEC) sensor using the heterostructure of a mixed metal oxide (CuCo₂O₄) coated on the surface of vertically aligned titanium dioxide nanotube arrays (TiO₂ NTAs) as the optoelectronic material. The suggested sensor with a remarkable UV-light photoelectrocatalytic activity, was utilized for the determination of galantamine (Gal), one of the most common Alzheimer's drugs, without any auxiliary biomolecules or labeled materials. At first, TiO₂ NTAs were synthesized by electrochemical anodizing in an organic medium containing ethylene glycol, ammonium fluoride and water, followed by calcination in the furnace. Afterward, a cobalt-copper alloy was electrodeposited on the TiO₂ NTAs using an electrochemical coating method for 30 s. The combination of CuCo₂O₄ with TiO₂ NTAs exhibited a superior photocurrent (roughly 1.41 times higher) than that of the bare TiO₂ NTAs/Ti electrode that was attributed to the efficient separation of electron hole pairs and rapid electron transfer. The addition of Gal led to an enhancing of the photoelectrochemical response of the CuCo₂O₄/TiO₂ NTA electrode due to the presence of Gal as a sacrificial electron donor to scavenge the hole and inhibit the recombination of photogenerated electron–hole pairs. Under the optimum conditions, the designed PEC sensor exhibited a good linear range of Gal concentrations from 10.0 nmol L⁻¹ to 10.0 μmol L⁻¹ with a detection limit (S/N = 3) of 7.65 nmol L⁻¹. The relative standard deviation was 0.71% (n = 10). Moreover, the as-fabricated PEC sensor exhibited an outstanding analytical performance with a high sensitivity, excellent selectivity, good stability and reproducibility, which opens up a new promising signal on the PEC sensor with enhanced sensing performances for the evaluation of Gal in pharmaceutical products with satisfactory results.