Engineering Interfacial Pt─O─Ti Site at Atomic Step Defect for Efficient Hydrogen Evolution Catalysis

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 Pt−1 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. The 5–10 nm TiO2 nanoparticles with abundant surface step defects are used to direct the uniform anchoring of Pt atomic clusters via Pt─O─Ti linkage. The low‐Pt catalysts (Pt‐ACs/S‐TiO2‐NP) exhibit exceptional hydrogen evolution reaction (HER) activity due to the unique step‐site Pi‐O‐Ti species. The work provides a deep insight on the interactions between high‐dimensional defect and well‐dispersed atomic metal motifs for superior HER catalysis.