Synergistic TiO₂-nanovoids and reduced graphene oxide platform: A competitive electrochemical material for Pb²⁺...

The combination of semiconducting TiO₂ with reduced graphene oxide (rGO) enables the design of hybrid materials with tunable properties that go beyond the capabilities of each component. The intimate contact between TiO₂ and rGO promotes efficient charge separation, enhanced electron transport, and an increased density of electroactive sites, resulting in superior electrical conductivity and surface activity. These interfacial effects make the TiO₂/rGO system an attractive platform for electrochemical sensing and environmental applications. In this work, we systematically explored the design, preparation and characterization of nanostructured composite electrodes based on TiO₂ nanovoids (TiO₂-NVs) and rGO for the electrochemical detection of Pb²⁺ in drinking water. The TiO₂-NVs/rGO composites were fabricated by drop-casting rGO onto TiO₂-NVs substrates, forming an interconnected heterointerface with tunable properties. Electrochemical characterization revealed that the rGO layer significantly improved the interfacial charge transfer and increased the active surface area. As a result, the TiO₂-NVs/rGO electrodes displayed reproducible and sensitive Pb²⁺ detection over a wide concentration range (0.0005-10 mg L^-1) with a detection limit of (0.0017 ± 0.0001) mg L^-1. For the interference study, Cd²⁺, Cu²⁺ and Fe³⁺ were evaluated to assess the selectivity of the proposed platform. The accuracy of the DPASV technique was demonstrated through recovery experiments in commercial mineral water, yielding percentages comparable to ICP-MS results. These findings highlight the crucial role of TiO₂-rGO interfacial engineering in optimizing electron transport and catalytic efficiency, positioning these composites as promising materials for electroanalytical and environmental monitoring applications.