Interface-Enhanced Thermal Localization in Ce-Doped Biphasic Nb2O5 via Oxygen Vacancies and Hot-Carrier Transport for Solar Evaporation

Abstract Defect and interface engineering were jointly introduced into Nb2O5 through Ce doping to enhance broadband light harvesting and hot-carrier transport for solar-driven interfacial evaporation. Ce incorporation induces oxygen vacancies, reconstructs the local Nb–O framework, and triggers the formation of a low-mismatch T/ζ biphasic interface with directional strain. This coupled structure generates a positive thermal-conductivity window absent in the single phases, together with higher hot-carrier concentration, longer low-frequency phonon lifetime, and more continuous local vibrational coupling. Finite-element simulations further reveal faster thermal-field buildup and stronger interfacial heat localization in the biphasic structure. As a result, Nb–Ce3.0 exhibits the highest thermal conductivity of 1.532 W m–1 K–1, a surface temperature of 62.3 °C with bulk water remaining at ≈33.4 °C, and evaporation rates of 1.343, 4.022, and 6.525 kg m–2 h–1 under 1, 3, and 5 sun, respectively, while maintaining effective seawater desalination.