A strongly polarized solid/liquid interface is constructed to create a “micro-hydrothermal” environment under microwave and promote reaction energy efficiency. Specifically, TiO₂ with open crystal structure was synthesized to maximize the density of surface-active centers and the degrees of interfacial polarization. Acidic groups were grafted on the catalyst surface, which served as catalytically active sites as well as heat-generation spots under microwave irradiation. Benefited by enhanced interfacial polarization, 10 times higher energy efficiency (6.8 mmol (kJ L)⁻¹) than commercial TiO₂ can be achieved in fructose dehydration reaction. MD simulation revealed that sulfonic group polarized surface water molecules and acted as “hot-spots” to accelerate fructose dehydration to HMF. Such alignment of site-specific heating and reaction by material design has great potential to shift the energy efficiency for a wide range of chemical reactions.