Graphene–nano/TiO2 as an integrated functional unit: DLS-guided dispersion–structure–performance coupling in cementitious composites

This study introduces a new approach using graphene-doped TiO 2 (G–TiO 2 ) composites as integrated functional units in cement-based materials and systematically investigates how their dispersion state influences multiple performance dimensions. For the first time, a quantitative dispersion-evaluation strategy combining dynamic light scattering (DLS) and a dispersion index (DI) is established to identify an optimal dispersion window and directly link dispersion quality with structural and multifunctional performance. The key finding is that ultrasonication within an optimal dispersion window, as identified by DLS-based dispersion analysis, produces a uniform particle distribution, refines pore structures, and densifies the interfacial transition zones (ITZs), thereby yielding higher 28-day compressive strength compared with insufficiently or excessively dispersed specimens. Concurrently, optimized dispersion facilitates the formation of continuous conductive networks and enhances Maxwell–Wagner–Sillars–type interfacial polarization by increasing the effective conductive–dielectric interfacial area, leading to peak electrochemical and thermoelectric outputs, with capacitance reaching 170 μF/cm 2 and Seebeck voltage up to 60 mV. Surface hydrophobicity also improves significantly under optimal dispersion conditions, with water contact angles increasing from 90° to 130°. In contrast, insufficient or excessive dispersion leads to agglomeration, sheet fragmentation, and the formation of defect pores, which degrades both mechanical and functional properties. Overall, this work elucidates a clear dispersion–microstructure–performance relationship in a G–TiO 2 cementitious system, providing quantitative experimental evidence that dispersion quality is a key governing factor in microstructural evolution and multifunctional performance enhancement in nanomaterial-modified cementitious composites.