https://www.science.org/doi/10.1126/science.adt0682
https://www.cas.cn/syky/202502/t20250217_5047276.shtml
The research group of Professor Zhou Wu of the University of the Chinese Academy of Sciences, in collaboration with the research group of Professor Martin of Peking University, the research group of Researcher Zhou Jihan of Peking University, and Professor Graham J. Hutchings of Cardiff University in the United Kingdom, have pioneered a new hydrogen production technology of “selective partial reforming” of the metal-molybdenum carbide system based on nearly ten years of collaborative research results of the Zhou Wu research group and the Martin research group in the metal-molybdenum carbide (M/α-MoC) catalyst system. This technology transforms the ethanol-water reforming reaction from the traditional full reforming (oxidation) path to a selective partial reforming path (C2H5OH + H2O → 2H2 + CH3COOH) by precisely designing and regulating the platinum/iridium (Pt/Ir) bimetallic-α-MoC interface at the atomic level, achieving high-throughput hydrogen production at 270°C and co-producing high-value chemicals (acetic acid).
This process eliminates direct CO2 emissions from the source of the reaction and converts carbon resources in the reactants into liquid chemicals with high selectivity. The core innovation of the new platinum-iridium bimetallic catalyst (PtIr/α-MoC) lies in the atomic-scale interface engineering design. Single-atom-resolved low-voltage scanning transmission electron microscopy (STEM) electron energy loss spectroscopy (EELS) imaging analysis shows that in the 3wt% loaded 3Pt/α-MoC catalyst, Pt species mainly exist on the MoC surface in the form of single atoms and clusters, where the size of the Pt clusters is about 1nm. After introducing a similar amount of Ir species into the catalyst, the dispersion of Pt species in the 3Pt3Ir/α-MoC catalyst is significantly improved, and Ir mainly exists in the form of highly dispersed single atoms. These findings are due to the different degrees of strong interaction between atomically dispersed Pt and Ir species and the α-MoC carrier. Among them, Ir preferentially settles on the carrier surface, promotes the dispersion of Pt and constrains the generation of Pt particles, thereby constructing a high-density interfacial catalytic active site, avoiding the formation of precious metal particles, and inhibiting the breakage of C-C bonds during the catalytic process. This design ensures that the catalyst can efficiently activate the ethanol-water system under mild conditions and maintain long-term stability.
Catalytic performance evaluation shows that the catalyst has a hydrogen yield of 331.3 mmol per gram of catalyst per hour at 270°C, an acetic acid selectivity of 84.5%, and excellent anti-deactivation ability in a 100-hour stability test. Compared with the traditional ethanol-water reforming reaction, this new technology has lower energy consumption, is more environmentally friendly, and provides a new path for the green preparation of acetic acid.
In this study, Zhou Wu’s research group used single-atom-resolved low-pressure STEM-EELS imaging technology for the first time to achieve atomic-level chemical imaging of adjacent precious metal species in the periodic table on the catalyst, revealing the promotion effect of single-atom Ir species on the carrier on the dispersion of Pt species. Compared with conventional STEM-HAADF atomic number contrast analysis, this technology shows advantages in complex systems with mixed multiple elements, and can more accurately analyze the strong interactions between supported metals and supported metals and between supported metals and carriers in bimetallic catalyst systems and even more complex catalyst systems.
