Yun Xu

Bio: Yun Xu is an academic researcher from Huazhong University of Science and Technology. The author has contributed to research in topics: Microelectrode & Nanotechnology. The author has an hindex of 3, co-authored 7 publications receiving 33 citations.

Applications of single-atom catalysts

Abstract: Owning to unsaturated coordination environment, quantum size effect and metal-support interaction, single- or dual-atom metal sites, such as Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, Sn, Ir, Pt, Au, Bi, and Er coordinated with nonmetallic elements such as O, N, P, and S, exhibit different electronic configurations, which endow them with high catalytic performances in multiple redox reactions and versatile applications in organic synthesis, environmental remediation, energy conversion, and biomedicine. Despite intense research, the relation of structure-activity for single-atom catalysts (SACs) still bedazzles researchers, since diversified configurations of active sites would bring about difficulty in structural identification and theoretical simulations. Here, recent results on the applications of SACs are reviewed with an emphasis on identifying the active sites and discussing the relation between structure and property.

Single-Atom (Iron-Based) Catalysts: Synthesis and Applications.

Abstract: Supported single-metal atom catalysts (SACs) are constituted of isolated active metal centers, which are heterogenized on inert supports such as graphene, porous carbon, and metal oxides. Their thermal stability, electronic properties, and catalytic activities can be controlled via interactions between the single-metal atom center and neighboring heteroatoms such as nitrogen, oxygen, and sulfur. Due to the atomic dispersion of the active catalytic centers, the amount of metal required for catalysis can be decreased, thus offering new possibilities to control the selectivity of a given transformation as well as to improve catalyst turnover frequencies and turnover numbers. This review aims to comprehensively summarize the synthesis of Fe-SACs with a focus on anchoring single atoms (SA) on carbon/graphene supports. The characterization of these advanced materials using various spectroscopic techniques and their applications in diverse research areas are described. When applicable, mechanistic investigations conducted to understand the specific behavior of Fe-SACs-based catalysts are highlighted, including the use of theoretical models.

A clicking confinement strategy to fabricate transition metal single-atom sites for bifunctional oxygen electrocatalysis

Abstract: Rechargeable zinc-air batteries call for high-performance bifunctional oxygen electrocatalysts. Transition metal single-atom catalysts constitute a promising candidate considering their maximum atom efficiency and high intrinsic activity. However, the fabrication of atomically dispersed transition metal sites is highly challenging, creating a need for for new design strategies and synthesis methods. Here, a clicking confinement strategy is proposed to efficiently predisperse transitional metal atoms in a precursor directed by click chemistry and ensure successful construction of abundant single-atom sites. Concretely, cobalt-coordinated porphyrin units are covalently clicked on the substrate for the confinement of the cobalt atoms and affording a Co-N-C electrocatalyst. The Co-N-C electrocatalyst exhibits impressive bifunctional oxygen electrocatalytic performances with an activity indicator ΔE of 0.79 V. This work extends the approach to prepare transition metal single-atom sites for efficient bifunctional oxygen electrocatalysis and inspires the methodology on precise synthesis of catalytic materials.

Electrochemical Water Splitting: Bridging the Gaps between Fundamental Research and Industrial Applications

Abstract: Electrochemical water splitting represents one of the most promising technologies to produce green hydrogen, which can help to realize the goal of achieving carbon neutrality. While substantial efforts on a laboratory scale have been made for understanding fundamental catalysis and developing high-performance electrocatalysts for the two half-reactions involved in water electrocatalysis, much less attention has been paid to doing relevant research on a larger scale. For example, few such researches have been done on an industrial scale. Herein, we review the very recent endeavors to bridge the gaps between fundamental research and industrial applications for water electrolysis. We begin by introducing the fundamentals of electrochemical water splitting and then present comparisons of testing protocol, figure of merit, catalyst of interest, and manufacturing cost for laboratory and industry-based water-electrolysis research. Special attention is paid to tracking the surface reconstruction process and identifying real catalytic species under different testing conditions, which highlight the significant distinctions of corresponding electrochemical reconstruction mechanisms. Advances in catalyst designs for industry-relevant water electrolysis are also summarized, which reveal the progress of moving the practical applications forward and accelerating synergies between material science and engineering. Perspectives and challenges of electrocatalyst design strategies are proposed finally to further bridge the gaps between lab-scale research and large-scale electrocatalysis applications.