Embedded-Type Cu Nanoparticle with Largely Enhanced Catalytic Activity and Stability Toward Methanol Steam Reforming

Hydrogen production through low-temperature methanol steam reforming (MSR) reaction plays a critical role in the development of new energy but remains a great challenge. Herein, we report a Cu/Zn(Ga)O_x catalyst, which is prepared via an interface reconstruction strategy. Interestingly, this catalyst is featured with a unique mortise-and-tenon structure: Cu nanoparticles are embedded into the Zn(Ga)O_x substrate, which ensures a stable Zn-O-Cu⁺-O_v-Ga^{δ +} interface structure. The resulting Cu/Zn(Ga)O_x catalyst exhibits 99.3% CH₃OH conversion with an H₂ production rate of 124.6 µmol g_cat ^-1 s^-1 at 225 °C, which is preponderant to the state-of-the-art catalysts. Furthermore, an ultra-high catalytic stability was demonstrated through a 400 h stream-on-line test without obvious decline. Kinetic isotope analysis, in situ spectroscopy characterizations, and theoretical calculations reveal that the MSR reaction over Cu/Zn(Ga)O_x catalyst follows the formaldehyde oxidation route. The CH₃O* and H₂O molecule adsorb at the adjacent Cu⁺-O_v interface (intrinsic active site) with an oxygen-terminal adsorption configuration, which promotes electron transfer from the d-band center of Cu to the O (s,p)-band of the substrate molecule. This significantly reduces the energy barrier of C─H bond cleavage in CH₃O* dehydrogenation (the rate-determining step) and H₂O dissociation, accounting for the extraordinarily enhanced H₂ production.