The aqueous-phase reforming of the methanol (APRM) reaction provides a potential approach for hydrogen (H2) storage and transportation. However, the limited capacity of Pt nanocatalysts for H2O activation leads to the drawback of requiring high reaction temperatures (>200 °C) to achieve efficient H2 generation through the APRM reaction. Herein, the electronic density of Pt nanocatalysts has been regulated by the phase of the Al2O3 supports. Mechanism analysis revealed that the α-Al2O3 supports with larger lattice fringe spacing resulted in an enhanced electronic density of Pt nanocatalysts, thereby enabling the effective adsorption and activation of H2O. Consequently, the Pt/α-Al2O3 catalysts exhibited a TOF value of 69.8 h–1 at 30 °C for H2 generation via APRM reaction. Notably, this H2 generation rate even suppressed that achieved by previous state-of-the-art homogeneous catalysts. This finding presents a promising avenue toward flexible hydrogen utilization.