Consecutive D‐Band Center Regulation of Yolk‐Shell C o 8 F e S 8 ‐ F e x C y for Enhanced Water Oxidation and Microwave Absorption

Electronic modulation for balancing oxygen intermediates bending energy over oxygen evolution catalytic active sites is one of the most critical factors but still remains challenging. In this case, yolk‐shell Co 8 FeS 8 ‐Fe x C y was constructed by fast Joule‐heating process with dual‐ligand PBA as precursor. With the help of Spherical aberration corrected STEM, synchrotron‐radiation photoelectron spectroscopy as well as DFT calculations, the consecutive manipulation of d‐band center for the designed series of Co 8 FeS 8 ‐based samples by introducing the Fe x C y with varying element ratios was disclosed. The findings confirm that electron modulation of Co 8 FeS 8 ‐Fe x C y can upshift the d‐band center toward Fermi level to optimize antibonding‐orbital occupancy of the metal‐O bond, thereby prominently minimizing Gibbs free energy for intermediates in the rate‐determining step. Encouragingly, the optimal Co 8 FeS 8 ‐Fe 7 C 3 delivers a significant overpotential (η 10 ) decrease by 118 mV compared with Co 8 FeS 8 ‐C, ultrasmall Tafel slope of 33.4 mV dec −1 , along with excellent catalytic durability. Furthermore, it also shows enhanced electromagnetic wave dissipation ability with the minimum reflection loss of −50.72 at 2.03 mm and effective absorption bandwidth of 7.87 GHz at 1.7 mm. This work uncovered the intrinsic regulation mechanism of microcomponent design and opens up a promising prospect for exploring advanced multifunctional materials.