Defect-trapped Pt single-site electrocatalysts

Lead authors Dr Peng Tang and Dr Po-Yuan Huang used STEM, XPS and operando XAS to confirm that trapped Pt-single site catalysts are stable at the HER potential, and that their electrocatalytic activity is inferior to Pt nanoparticles.

In their paper 'Structure-property relationship of defect trapped Pt single-site electrocatalysts for the Hydrogen evolution reaction' published in ACS Catalysis, they and their collaborators used in situ heated scanning transmission electron microscopy and temperature-dependent X-ray photoelectron spectroscopy to clarify the thermally induced structural evolution of Pt during pyrolysis.  The results showed that the nitrogen in polyaniline coordinates with Pt ions, and atomically disperses them before pyrolysis and traps Pt sites at pyridinic N defects generated during the substrate graphitisation.

Operando X-ray absorption spectroscopy confirmed that the trapped Pt-SSC is stable at the HER working potentials, but with inferior electrocatalytic activity compared with metallic Pt nanoparticles.  First principle calculations suggest that the inferior activity of trapped Pt-SSCs was due to their unfavourable hydrogen chemisorption energy relative to metallic Pt (111) surfaces.

These results further the understanding of the structure-property relationship in trapped Pt-SScs and motivate a detailed techno-economic analysis to evaluate their commercial applicability.