Low‐Temperature Hydrogenation of CO<sub>2</sub> to Methanol in Water on ZnO‐Supported CuAu Nanoalloys
Jawaher Mosrati, Tamao Ishida, Dinh Hung Mac, Mohammed Al‐Yusufi, Tetsuo Honma, Magdalena Parlińska‐Wojtan, Yasuhiro Kobayashi, Alexander Klyushin, Toru Murayama, Ali M. Abdel‐Mageed
Abstract
Abstract Optimizing processes and materials for the valorization of CO 2 to hydrogen carriers or platform chemicals is a key step for mitigating global warming and for the sustainable use of renewables. We report here on the hydrogenation of CO 2 in water on ZnO‐supported CuAu nanoalloys, based on ≤7 mol % Au. Cu x Au y /ZnO catalysts were characterized using 197 Au Mössbauer, in situ X‐ray absorption (Au L III ‐ and Cu K‐edges), and ambient pressure X‐ray photoelectron (APXP) spectroscopic methods together with X‐ray diffraction and high‐resolution electron microscopy. At 200 °C, the conversion of CO 2 showed a significant increase by 34 times (from 0.1 to 3.4 %) upon increasing Cu 93 Au 7 loading from 1 to 10 wt %, while maintaining methanol selectivity at 100 %. Limited CO selectivity (4–6 %) was observed upon increasing temperature up to 240 °C but associated with a ≈3‐fold increase in CO 2 conversion. Based on APXPS during CO 2 hydrogenation in an H 2 O‐rich mixture, Cu segregates preferentially to the surface in a mainly metallic state, while slightly charged Au submerges deeper into the subsurface region. These results and detailed structural analyses are topics of the present contribution.