Ultrahigh Mass Activity for Carbon Dioxide Reduction Enabled by Gold-Iron Core-Shell Nanoparticles.

Wide application of carbon dioxide (CO2) electrochemical energy storage requires catalysts with high mass activity. Alloy catalysts can achieve superior performance to single metals while reducing the cost by finely tuning the composition and morphology. We used in silico quantum mechanics rapid screening to identify Au-Fe as a candidate improving CO2 reduction and then synthesized and tested it experimentally. The synthesized Au-Fe alloy catalyst evolves quickly into a stable Au-Fe core-shell nanoparticle (AuFe-CSNP) after leaching out surface Fe. This AuFe-CSNP exhibits exclusive CO selectivity, long-term stability, nearly a 100-fold increase in mass activity toward CO2 reduction compared with Au NP, and 0.2 V lower in overpotential. Calculations show that surface defects due to Fe leaching contribute significantly to decrease the overpotential.

Medium-energy microprobe station at the SXRMB of the CLS.

Micro-XAFS and chemical imaging techniques have been widely applied for studies of heterogeneously distributed systems, mostly in hard X-ray (>5 keV) or in soft X-ray (<1.5 keV) energies. The microprobe endstation of the SXRMB (soft X-ray microcharacterization beamline) at the Canadian Light Source is optimized at the medium energy (1.7-5 keV), and it has been recently commissioned and is available for general users. The technical design and the performance (energy range, beam size and flux) of the SXRMB microprobe are presented. Examples in chemical imaging and micro-XAFS in the medium energy for important elements such as P, S and Ca for soil and biological samples are highlighted.