The low intrinsic activity of Fe/N/C oxygen catalysts restricts their commercial application in the fuel cells technique; herein, we demonstrated the interface engineering of plasmonic induced Fe/N/C-F catalyst with primarily enhanced oxygen reduction performance for fuel cells applications. The strong interaction between F and Fe-N₄ active sites modifies the catalyst interfacial properties as revealed by X-ray absorption structure spectrum and density functional theory calculations, which changes the electronic structure of Fe-N active site resulting from more atoms around the active site participating in the reaction as well as super-hydrophobicity from C–F covalent bond. The hybrid contribution from active sites and carbon support is proposed to optimize the three-phase microenvironment efficiently in the catalysis electrode, thereby facilitating efficient oxygen reduction performance. High catalytic performance for oxygen reduction and fuel cells practical application catalyzed by Fe/N/C-F catalyst is thus verified, which offers a novel catalyst system for fuel cells technique.

Artificial defect engineering in transition metal oxides is of important terms for numerous applications. In the present work, we proposed an in-situ gas reduction strategy to introduce ordered defects into titanium niobium oxide embedding on vapor grew carbon fibers (Ti₂Nb₁₀O_29–x@VGCFs). High-resolution transmission electron microscopy (HRTEM) and fast Fourier transform (FFT) simulation indicate that the ordered oxygen defects locate at interval layers, which leads to a new superstructure in Ti₂Nb₁₀O₂₉. The ordered defects could provide extra active sites for lithium-ion storage and modulate ionic migration, resulting an enhanced pseudocapacitive performance. In addition, the excellent structural stability of the superstructure was proved by in-situ HRTEM under a harsh electrochemical process. Our work provides a directly observation of orderly defective superstructure in transition metal oxide, and its functionality on electrochemistry was revealed.