Nb-Promoted Pt/MoO_x/TiO₂ Catalysts for Low-Temperature CO₂ Hydrogenation to Methanol

The catalytic hydrogenation of carbon dioxide (CO₂) to methanol under mild conditions presents a sustainable route for carbon recycling and chemical energy storage. However, the inert nature of CO₂ and high activation energy barrier for methanol formation remain major challenges. In this study, we developed a series of Nb-promoted Pt/MoOx/TiO₂ catalysts for efficient CO₂ hydrogenation at temperatures below 200 °C. Among these, Pt(5)/Mo(10)-Nb(1)/TiO₂ exhibited superior performance, achieving a high methanol productivity of 3.8 mmol g_cat ^-1 h^-1 at 150 °C, outperforming the commercial Cu-ZnO/Al₂O₃ catalyst under comparable conditions. The catalyst showed stable performance during a 400 h long-term reaction. Detailed in situ and operando spectroscopic studies revealed that Pt sites were primarily responsible for H₂ activation, while partially reduced MoO_x species facilitated the formation of oxygenated intermediates. The incorporation of highly dispersed Nb species promoted methanol desorption and inhibited its decomposition, thereby contributing to the overall catalytic efficiency. This study outlines a rational design approach for constructing robust low-temperature catalysts and provides mechanistic insights into the synergistic roles of the metal and oxide components in CO₂-to-methanol conversion.