Carbon-based single-atom catalysts (C-SACs), featured with flexible, well-defined atomic geometry and superior electrical conductivity, have experienced a rapid development in the last decade and proved unique opportunities in selective oxygen...
The significant increase of catalytic efficiency while remaining low Pt usage is constantly pursued, but remains a challenge. Here, a “vacuum‐assisted” (VA) process toward Pt clusters dispersed on SAPO‐11 (S‐11) is shown for a high‐effective hydroisomerization of n‐C16. The VA can make effective trapping of the Pt precursor on S‐11 due to intensive capillary action, being conductive to stabilize and disperse Pt cluster (≈1 nm) on S‐11 (V‐Pt/S‐11) for promoting synergy of Pt sites and acid sites on S‐11. The test indicates excellent catalytic activity and stability of trace Pt clusters (0.15 wt%, even lower, 0.035 wt%) on S‐11 (≈94.4% isomer selectivity at 94.3% conversion), much superior to I‐0.15 wt% Pt/S‐11 from traditional impregnation routes (≈88% selectivity at 90% conversion) and ever reported catalysts. The V‐Pt/S‐11 is also superior for the hydroisomerization of catalytic diesel oil with a decrease of freezing point up to 40 °C after hydroisomerization. The superior performance is attributed to the exposure of high acid density due to little coverage of Pt cluster on S‐11, high dispersion of Pt leading to form more metal–acid bifunctional sites, and enhanced (de)hydrogenation ability of Pt clusters. All of them can promote the effective synergy of metal sites (Pt) and acid sites.
Understanding the nature of single‐atom catalytic sites and identifying their spectroscopic fingerprints are essential prerequisites for the rational design of target catalysts. Here, we apply correlated in situ X‐ray absorption and infrared spectroscopy to probe the edge‐site‐specific chemistry of Co−N−C electrocatalyst during the oxygen reduction reaction (ORR) operation. The unique edge‐hosted architecture affords single‐atom Co site remarkable structural flexibility with adapted dynamic oxo adsorption and valence state shuttling between Co(2−δ)+ and Co2+, in contrast to the rigid in‐plane embedded Co1−Nx counterpart. Theoretical calculations demonstrate that the synergistic interplay of in situ reconstructed Co1−N2‐oxo with peripheral oxygen groups gives a rise to the near‐optimal adsorption of *OOH intermediate and substantially increases the activation barrier for its dissociation, accounting for a robust acidic ORR activity and 2e− selectivity for H2O2 production.
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