Fig. 2: Microstructure of the cocatalysts.

a, b HAADF-STEM images of PtSA/NP-TiO2-xBx. c HAADF-STEM, high-resolution image (inset), and the corresponding histogram of PtNP particle size distribution (inset) of the PtSA/NP-TiO2-xBx photocatalysts, the NPs size ranges from 1 to 3.8 nm, with ~ 80% of the NPs falling between 1.5 and 2.5 nm, yielding an average size of 2.08 nm. d The corresponding atomic intensity profiles of Line 1 marked in b. e DRIFTS spectra of CO adsorption on PtSA/NP-TiO2-xBx. f CO-DRIFTS spectra of PtSA-TiO2-xBx, PtSA/NP-TiO2-xBx and PtNP-TiO2-xBx, the peak at ~ 2096 cm⁻¹ is assigned to linear CO adsorption on Pt SAs of PtSA-TiO2-xBx, and the peaks at ~ 2055 cm⁻¹ and ~ 1825 cm⁻¹ are attributed to linear and bridged CO adsorption on Pt NPs of PtNP-TiO2-xBx, respectively. g Ti, O, B and Pt element mappings of PtSA/NP-TiO2-xBx. Source data are provided as a Source Data file.