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Abstract The electrocatalytic CO ₂ RR to produce value‐added chemicals and fuels has been recognized as a promising means to reduce the reliance on fossil resources; it is, however, hindered due to the lack of high‐performance electrocatalysts. The effectiveness of sculpturing metal/metal oxides (MMO) heterostructures to enhance electrocatalytic performance toward CO ₂ RR has been well documented, nonetheless, the precise synergistic mechanism of MMO remains elusive. Herein, an in operando electrochemically synthesized Cr ₂ O ₃ –Ag heterostructure electrocatalyst (Cr ₂ O ₃ @Ag) is reported for efficient electrocatalytic reduction of CO ₂ to CO. The obtained Cr ₂ Omore » ₃ @Ag can readily achieve a superb FE _CO of 99.6% at −0.8 V (vs RHE) with a high J _CO of 19.0 mA cm ⁻² . These studies also confirm that the operando synthesized Cr ₂ O ₃ @Ag possesses high operational stability. Notably, operando Raman spectroscopy studies reveal that the markedly enhanced performance is attributable to the synergistic Cr ₂ O ₃ –Ag heterostructure induced stabilization of CO ₂ ^•− /*COOH intermediates. DFT calculations unveil that the metallic‐Ag‐catalyzed CO ₂ reduction to CO requires a 1.45 eV energy input to proceed, which is 0.93 eV higher than that of the MMO‐structured Cr ₂ O ₃ @Ag. The exemplified approaches in this work would be adoptable for design and development of high‐performance electrocatalysts for other important reactions.« less

In this study, we aim to obtain a fundamental understanding of active sites near stone-wales (SW) defects rich nitrogen-doped graphene (DG) with specific coordination of carbon atom rings. It reveals that the SW rich defects (e.g., pentagon (5), pentagon—octagon—pentagon (i.e. 585), or pentagon-heptagon-heptagon-pentagon (5775) rings, appears correspondingly with carbon rings that brought active sites during catalytic reactions. Moreover, we anchored dual isolated metallic atoms (Ni/Fe) on DG support via linkers (O/N) called NiFe-DG. X-ray absorption spectroscopy indicates Ni/Fe metal single atoms are embedded via Fe-N₄ and Ni-N₄ coordination on DG surfaces. It exhibits high catalytic activity for oxygen reduction reactionmore » (ORR) with an onset potential of 0.97 V, a half-wave potential of 0.86 V, and diffusion current density of 5.7 mA cm^{– 2}, which is at par with commercial Pt/C. The catalyst shows superior stability, retained 82% of the initial current density even after 12 h under an applied potential of 0.86 V. Similarly, the oxygen evolution reaction (OER) overpotential of 358 mV was achieved at 10 mA cm^{– 2} with a lower Tafel slope value (76 mV/dec) than commercial Pt/C. It maintains 85% stability for 12 h at a constant potential of 1.588 V, shows better stability than commercial Pt/C.« less