Wide application of carbon dioxide (CO) 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 CO 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 CO 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.

The understanding of the interaction between the building blocks in the hybrids can advance our comprehension of design principles in high-performance microwave absorbing materials. Here, we report a hybrid material consisting of magnetite (Fe3O4) nanocrystals grown on multiwalled carbon nanotube (MWCNT) as a high-performance microwave absorber in the 2–18 GHz band, although Fe3O4 nanocrystals or MWCNTs alone or their physical mixture show little microwave absorption. The hybrid is characterized by transmission electron microscopy, X-ray diffraction, and vector network analysis, X-ray absorption near-edge structures at the C K-edge and Fe L3,2-edge, and electron spin resonance analysis. Microstructural analysis reveals that Fe3O4 nanocrystals are immobilized on the MWCNT surface by a strong interaction. Charges in the MWCNT/Fe3O4 hybrids transfer from the conduction band in Fe3O4 to C 2p-derived states in the MWCNT substrate. Dipole interaction between the magnetic nanocrystals is increased. The synergetic interactions leads to much improved microwave absorption.

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A chemoselective route to induce Fe3O4@ZnO core-shell nanoparticles decorating carbon nanotubes to form MWCNT/Fe3O4@ZnO heterotrimers has been developed. Charges are redistributed in the heterotrimers through C-O-Zn, C-O-Fe and Fe-O-Zn bondings, giving rise to multiple electronic phases. The generated significant interfacial polarization and synergetic interaction between dielectric and magnetic absorbers result in the MWCNT/Fe3O4@ZnO heterotrimers with high-performance microwave absorption in an entire X band.

The interaction between components in hybrids is an indispensable factor in designing and fabricating composites with distinguished electromagnetic (EM) absorption performances. Herein, covalently bonded SiC/Co hybrid nanowires (NWs) have been fabricated, which present significantly enhanced EM absorption compared to a simple physical mixture of SiC and Co. The hybrids are characterized by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, vector network analysis, and X-ray absorption near-edge spectroscopy at the Si K-edge, C K-edge, Co L 3,2 -edge and O K-edge. Microstructure analysis indicates the formation of Si-O-Co bonds between SiC NWs and magnetic Conanocrystals. Charge transfer takes place in the covalently bonded SiC/Co hybrid NWs. The induced synergistic coupling interaction in SiC/Co leads to an effective EM absorption band (RL < À10 dB) covering the frequency range of 10-16.6 GHz when the Co content is 25.1 wt% in the hybrid.