Enhancing catalytic H2 generation by surface electronic tuning of systematically controlled Pt-Pb nanocrystals

Abstract

Although many previous studies have shown that the shape-control of nanocrystal (NCs) is an efficient strategy to improve the catalytic performance, these syntheses were conducted under very different conditions, which are not suitable for the shape-dependent properties studies as well as catalysis optimization. Herein, we demonstrate an effective method for the selective synthesis of well-defined PtPb NCs in a highly controllable manner. Four distinct PtPb NCs, namely PtPb peanut nanocrystals, PtPb hexagonal nanoplates, PtPb octahedra nanocrystals (ONCs) and PtPb nanoparticles have been selectively prepared in the presence of different phenols. Significantly, we found that the created PtPb NCs/C shows the shape-dependent activity with the optimized PtPb ONCs/C being the most active for the ethanol reforming to H2, 22.4 times higher than the commercial Pt/C. The high performance of PtPb ONCs/C has been also successfully expanded into other polyhydric alcohols reformings. X-ray photoelectron spectroscopy (XPS) reveals that the high Pt(0)/Pt(II) ratio in PtPb NCs/C enhances the alcohols reforming. The density functional theory (DFT) studies show the PtPb ONCs possess the highest surface averaged electronic occupation for unit Pt-atom, matching well with XPS results. The PtPb ONCs/C also displays excellent durability with limited activity decay and negligible structure/composition changes after ten cycles. This work demonstrates an important advance in the high-level control of metallic nanostructures to tune the catalytic activities.