Nickel Metal–Organic Framework combined with Titanium Dioxide (Ni-MOF/TiO₂) composite has been successfully prepared and explored as an effective electrochemical sensing platform to detect ultra-trace levels of Cu 2+ and Pb 2+ ions. Powder X-ray diffraction (PXRD) was used to determine the high crystallinity of the composite, whereas FTIR spectroscopy was used to determine the presence of characteristic functional groups and metal-ligand interactions in the composite structure. FE-SEM and HRTEM morphological analysis indicated a very porous surface with non-spherical irregular architecture, and particle sizes of 100-170 nm. The EDX analysis further ensured that the elements of Ni, Ti, C, and O have been incorporated successfully in the composite. UV- visible spectroscopy revealed a very high absorption at 331.9 nm, and the optical band gap was about 3.01 eV. The analysis of nitrogen adsorption and desorption showed that the mesoporous structure was formed with a specific surface area of 19.85m 2 g –1 and an average pore diameter of 6.1 nm. Electrochemical experiments in Na-citrate buffer (pH 5.0) revealed the rapid kinetics of electron-transfer, with a diffusion coefficient of 7.30 × 10 –5 cm 2 s –1 and a low charge-transfer resistance (R ct ) of 306Ω being recorded at the Ni-MOF/TiO 2 -modified electrode. Pulse voltammetry provided the ability to determine Cu 2+ and Pb 2+ in a linear concentration range of 1-10nM. The sensor had 11.79 µA nM –1 cm –2 and 3.65 µA nM –1 cm –2 sensitivities to Cu 2+ and Pb 2+ ions, respectively, with low detection limits of 2.58 nM and 2.55 nM. The sensor had a high stability of 89% of its original response over time. It was also used successfully to analyze real-time soil samples (5-15 nM), the recoveries being 97-101%. These findings indicate the high potential of the Ni-MOF/TiO 2 composite as a sensitive electrochemical sensor for detecting heavy metals in the environment.
D et al. (2026) studied this question.