Analysis of Electronic State of Pt Small Particles on Carbon Substrate by sXPS

The effect of the size of a platinum particle on its electronic structure was measured by soft X-ray photoemission spectroscopy and calculated by a first principle calculation. The measured particle size dependence of d-band center, which is considered as a good indicator of the electronic state related with the catalytic activity for oxygen reduction reaction, showed the shift of the d-band center to lower in energy, i.e. further away from the Fermi level, for smaller particle less than about 2nm. This trend did not agreed with the theoretical calculation result.