Evolution of High-Index Facets Pt Nanocrystals Induced by N-Defective Sites in the Integrated Electrode for Enhanced Methanol Oxidation

Highly efficient and durable Pt electrocatalysts are the key to boost the performance of fuel cells. The high-index facets (HIF) Pt nanocrystals are regarded as excellent catalytic activity and stability catalysts. However, nucleation, growth and evolution of high-index facets Pt nanocrystals induced by defective sites is still a challenge. In this work, tetrahexahedron (THH) and hexactahedron (HOH) Pt nanocrystals are synthesized, which are loaded on the nitrogen-doped reduced graphene oxide (N-rGO) support of the integrated electrodes by the square wave pulse method. Experimental investigations and density functional theory (DFT) calculations are conducted to analyze the growth and evolution mechanism of HIF Pt nanocrystals on the graphene-derived carbon supports. It shows that the H adsorption on the N-rGO/CFP support can induce evolution of Pt nanocrystals. Moreover, the N-defective sites on the surface of N-rGO can lead to a slower growth of Pt nanocrystals than that on the surface of reduced graphene oxide (rGO). Pt/N-rGO/CFP (20 min) shows the highest specific activity in methanol oxidation, which is 1.5 times higher than that of commercial Pt/C. This research paves the way on the design and synthesis of HIF Pt nanocrystal using graphene-derived carbon materials as substrates in the future. The novel Pt/rGO/CFP and Pt/N-rGO/CFP integrated electrodes are synthesized by the square wave pulse method. The mechanism of nucleation, evolution and distortion of HIF Pt nanocrystals on the graphene-derived carbon supports are studied. It shows that the N-defective sites on the surface of N-rGO/CFP can lead to a slower growth and different evolution of Pt nanocrystals compared to that on rGO/CFP.image