Recently, the research group of Prof. Zeng has made a great breakthrough in single-atom catalysis. The researchers demonstrated the synergetic interaction between neighboring monomers by constructing atomically dispersed Pt atoms on MoS₂ (Pt₁/MoS₂). The synergy was reflected by the S atoms between neighboring Pt monomers. This work has been published on the latest issue of Nature Nanotechnology with the title of “Synergetic Interaction between Neighbouring Pt Monomers in CO₂ Hydrogenation” and selected as the cover paper [Nature Nanotechnology, 2018, 13, 411-417].

Recently, atomically dispersed catalysts have drawn increasing research attention owing to the high atom utilization, low-coordination number of metal atoms, and strong metal-support interaction. Currently, the investigation on single-atom catalysis only focused on the isolated metal atoms or the interaction between metal atoms and supports. Whether the interaction between isolated active sites in single-atom catalysts exists still remains as a major question.

The researchers revealed the synergetic interaction between Pt monomers by facilely increasing the Pt mass loading up to 7.5% while still maintaining the atomic dispersion of Pt. In Pt₁/MoS₂, Pt atoms replaced Mo atoms in MoS₂ nanosheets, wherein every Pt atom and its directly-bonded S atoms composed an “active center”. When two active centers were partly overlapped or adjacent, the two relevant Pt atoms were regarded as neighboring monomers. During CO₂ hydrogenation, neighboring Pt monomers exhibited higher activity than isolated ones. The researchers further investigated the catalytic mechanism of different types of Pt monomers by combining temperature-programmed desorption, in-situ diffuse reflectance infrared Fourier transform, and in-situ X-ray photoelectron spectroscopy, and density functional theory calculations. Mechanistic studies reveal that CO₂ was converted into methanol without experiencing the formation of formic acid intermediates over isolated Pt monomers. In contrast, neighboring Pt monomers worked in synergy to alter reaction pathways, where CO₂ undergoes sequential transformation into formic acid and methanol.

This work for the first time proposes the concept of synergetic catalysis over neighboring monomers and breaks the stereotype that the active centers in single-atom catalysts are isolated without any interaction. This work also shows that the synergy works via the coordinated atoms, offering a new research direction in single-atom catalysis.

This work was supported by the CAS, MOST, NSFC, and National Synchrotron Radiation Laboratory.

Cover image: Guoyan Wang and Yanbing Ma

Source: http://www.nature.com/articles/s41565-018-0089-z