Abstract
In this work, a Dawson-type lithium polyoxometalate Li₆[α-P₂W₁₈O₆₂]·28 H₂O (LiPOM), was synthesized and thoroughly characterized using X-ray diffraction (XRD), phosphorus-31 nuclear magnetic resonance (³¹P NMR), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) techniques and Brunauer-Emmett-Teller (BET) surface area analysis techniques to confirm its structural integrity and morphology. The catalytic performance of LiPOM for hydrogen production via NaBH₄ methanolysis was systematically investigated under varying reaction temperatures, catalyst dosages, and NaBH₄ concentrations. The obtained results demonstrate that LiPOM exhibits enhanced hydrogen evolution efficiency compared with similar catalytic systems reported in the literature. Kinetic analysis based on the Arrhenius model yielded an activation energy of 28.12 kJ mol⁻¹, enthalpy of 25.56 kJ mol⁻¹, and entropy of - 128.98 J mol⁻¹ K⁻¹. The improved catalytic activity is attributed to the preserved Dawson-type framework and the highly rough surface morphology of LiPOM, which together facilitate effective reactant interaction and borohydride activation. These findings indicate that lithium-stabilized Dawson-type POMs are promising catalysts for environmentally benign hydrogen production processes.