Mesoporous Carbon Modified with Different Density of Thiophenic-Like Functional Groups and Their Effect on Platinum Nanoparticles Activity for Oxygen Reduction

Metal-support interaction between sulfur-doped carbon support (SMC) and Pt NPs was investigated, aiming at verifying how sulfur functional groups can improve the electrocatalytic performance of Pt NPs towards oxygen reduction (ORR). SMC were synthetized, tailoring the density of sulfur functional groups, while Pt NPs were deposited by thermal reduction of Pt(acac)2. The extent of the metal support interaction was proved by XPS analysis which revealed a strong electronic interaction, proportional to the density of sulfur defects, whereas XRD spectra evidenced a higher strain in Pt NPs loaded on SMC. DFT simulations confirmed that the metal-support interaction was strongest in the presence of a high density of sulfur defects. The combination of microstrain and electronic effects resulted in a high catalytic activity of supported Pt NPs towards ORR, with linear correlations of E1/2 or jk with the sulfur content in the support. Furthermore, a mass activity value (550 A g-1) well above the United States Department of Energy target of 440 A g-1 at 0.9 V vs. RHE, was determined.