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摘要
The hydrogen evolution reaction (HER) activity of defect-stabilized low-Pt-loading catalysts is closely related with defect type in support materials, while the knowledge about the effect of higher-dimensional defects on the property and activity of trapped Pt atomic species is scarce. Herein, small size (5-10 nm) TiO2 nanoparticles with abundant surface step defects (one kind of line defect) are used to direct the uniform anchoring of Pt atomic clusters (Pt-ACs) via Pt-O-Ti linkage. The as-made low-Pt catalysts (Pt-ACs/S-TiO2-NP) exhibit exceptional HER intrinsic activity due to the unique step-site Pi-O-Ti species, in which the mass activity and turnover frequency are as high as 21.46 A mg (-1)(Pt) and 21.69 s(-1) at the overpotential of 50 mV, both far beyond those of benchmark Pt/C catalysts and other Pt-ACs/TiO2 samples with less step sites. Spectroscopic measurements and theoretical calculations reveal that the step-defect-located Pt-O-Ti sites can simultaneously induce the charge transfer from TiO2 substrate to the trapped Pt-ACs and the downshift of d-band center, which helps the proton reduction to H* intermediates and the following hydrogen desorption process, thus improving the HER. The work provides a deep insight on the interactions between high-dimensional defect and well-dispersed atomic metal motifs for superior HER catalysis.
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