MOF-derived Pt/CeO₂ catalysts with N and Zr co-doping for enhanced hydrogen production via aqueous phase reforming of methanol

This study investigated the role of nitrogen (N) and zirconium (Zr) dopants in enhancing the catalytic performance of Pt/CeO₂ catalysts for hydrogen production via aqueous phase reforming (APR) of methanol. Metal-organic frameworks (UiO-66) were used as a versatile platform material for the preparation of the CeO₂-ZrO₂ solid solution with tunable Ce/Zr ratios and high surface area. g-C₃N₄ was used as an in-situ nitrogen source for the incorporation of interstitial N heteroatoms on the surface of CeO₂-ZrO₂ oxide. In comparison with the parent Pt/CeO₂, the N and Zr co-doped Pt/Zr_1:5-CeO₂-2N catalyst showed a significant increase in the turnover frequency (TOF) for the production of H₂ from 935 h⁻¹ to 2034 h⁻¹ at 200 °C. Meanwhile, the CO selectivity was decreased from 1.76 % to 0.99 %, indicating an enhanced water-gas shift (WGS) reaction. X-ray photoelectron spectroscopy (XPS) revealed that the oxygen vacancies (O_v) ratio of Pt/Zr_1:5-CeO₂-2N increased from 34.02 % to 66.54 %, indicating that N doping primarily affects the surface O_v. Electron spin resonance (ESR) confirmed an increase in the concentration of O_v, while H₂-TPR analysis showed improved oxygen species mobility with Zr doping, which further boosted catalytic efficiency. These findings suggest that the increased surface O_v concentration provided by N doping, along with Zr doping impact on bulk oxygen, led to an enhanced catalytic performance in the APR process. © 2025 Elsevier B.V.