Yingying Guo,Chenhui Wang,Yuhang Xiao,Xiaohong Tan,Weidong He,Jianpo Chen,Yan Li,Hao Cui,Chengxin Wang
Fe single-atom catalysts (SACs) have emerged as a promising alternative to platinum for catalyzing oxygen reduction reactions (ORR). Nevertheless, their practical applicability is hindered by insufficient stability caused by structural corrosion during ORR. Here, we developed an effective strategy to optimize and stabilize the Fe SAs (single-atoms) sites by implanting chromium (Cr) atomic clusters (ACs) to address the formidable deactivation issue of the best-performing yet unstable Fe-N-C catalysts. Cr AC -Fe 1 /N-S-C demonstrates an amazing stability with a negligible decline in activity after 100,000 CV cycles, and can maintain 81% of initial current after a continuous 50-hour operation period. Theoretical calculations and experimental evidence substantiate that the integration of Cr ACs not only weakens the binding of OH* to the Fe site, thereby facilitating the ORR process, but also eliminates in situ-generated reactive oxygen species (ROS) and retards Fe ion leaching from active sites, thus stabilizing of the Fe SA sites.
Yaxing Liu,Weiyin Li,Guizhe Zhao,Gang Qin,Yuexia Li,Yaqing Liu
The lack of direct insight into the microstructural evolution of catalytic materials under electrochemical polarization has inhibited the development of heterogeneous catalysts. By investigating a typical Au@Pd core–shell nanostructure, the present study discloses the microstructural evolution of heterogeneous catalytic materials during the methanol electrooxidation reaction (MOR). The electrocatalytic activity of the as-prepared Au@Pd_core–shell nanoparticles continuously increased during the first 100 successive voltammetry cycles of the MOR. Microstructural characterization studies revealed that during the MOR, an Au/Pd mixed bimetallic shell was formed by the self-driven microstructural evolution of the Au@Pd_core–shell nanoparticles. Both the experimental and calculation results indicated that the Au/Pd mixed bimetallic shell reduced the binding strength of OH− and CO on the catalyst surface. The exposed Au atoms in the shell region also produced large-scale reactive ˙OH radicals that facilitated the oxidative removal of the adsorbed carbonaceous species from the adjacent Pd active sites.
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