Subsurface-Controlled CO2 Selectivity of PdZn Near-Surface Alloys in H2 Generation by Methanol Steam Reforming


  • This work was financially supported by the Austrian Science Fund through grant P208920-N19 and the TU Vienna (IP-VSFG). C.R. acknowledges a PhD scholarship granted by the Max Planck Society. Support for the measurements at HZB/BESSY II was granted through EU program RII3-CT-2004-506008, proposal No. 2008_2_80336. The authors thank the HZB/BESSY II staff for their support of the in situ X-ray photoemission spectroscopy.


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More than skin deep: In spite of their identical 1:1 surface composition, the geometric and electronic structures of a multilayer and monolayer PdZn surface alloy are different, as are their catalytic selectivities. The CO2 selective multilayer alloy features surface ensembles of PdZn exhibiting a “Zn-up/Pd-down” corrugation (see picture). These act as “bifunctional” active sites both for water activation and for the conversion of methanol into CO2. On the monolayer alloy CO and not CO2 is produced.