Enhancing Heterogeneous Catalysis by Electronic Property Regulation of Single Atom Catalysts

Abstract

Past decades have witnessed the flourish of single atom catalysts (SACs) owing to their high atom-utilization efficiency and completely exposed active sites, which endows SACs with remarkably enhanced catalytic activities for various reactions. In the early development stage of SACs, researchers focus on the improvement of the catalytic performance of the catalysts, whereas the intrinsic catalytic reaction mechanism and the relationship between the electronic states of the metal sites and catalytic performance are usually ignored. Moreover, some sophisticated and complex structures, such as dualatom SACs, heteroatomic doped SACs, SACs with precise second coordination shell, and other synergetic catalysts containing SACs, were fabricated recently. The insight into electronic metal-support interaction (EMSI) aids the understanding of the catalytic mechanism and thus serves as a guide for the fabrication of heterogeneous catalysts. Notably, the uniform active sites and characteristic local coordination configuration of SACs provide excellent platforms to study EMSI and bridge the gap between homogeneous and heterogeneous catalysts, which will contribute to the understanding of structure-performance relationships and enhance the development of SACs and rational design of heterogeneous catalysts. EMSI is especially important in heterogeneous catalysis. Through the rational design of the local coordination environment of SACs, the electronic structure of active sites can be accurately regulated, which will shift their d-band centers. This significantly alters the adsorption capability of intermediates and influences the final catalytic performance of the catalysts. With the development of advanced operando characterization techniques, the evolution of configuration, electronic properties, and local coordination environment could be revealed, thus providing researchers with a clear picture of the intrinsic mechanism of the catalytic system. In addition, with the aid of theoretical calculations, catalyst screening will be considerably more convenient, which will significantly reduce the number of aimless trials. After the optimal structure is determined, researchers should devise precise fabrication methods to realize the configuration. Herein, we initially introduce the basic principles and effects of EMSI. The stabilization, electronic property regulation, and electron transfer tunneling effects of EMSI are the foundation of SACs synthesis and catalytic mechanism elucidation, of which the former requires strong coordination stabilization energies while the latter focuses on the electronic state evolution of the active sites. Subsequently, EMSI applications in several important heterogeneous catalysis processes, such as selective hydrogenation, alcohol oxidation, water-gas shift reaction, and hydroformylation, are reviewed. Finally, the review discusses the challenges and future prospects for the future development of EMSI on SACs.

S-Scheme Heterojunction/Single-Atom Dual-Driven Charge Transport for Photocatalytic Hydrogen Production

“…In the past decade, single atom catalysts (SACs) have received widespread attention in heterogeneous catalysis due to their 100% atom utilization, unique electronic structures, and tunable local coordination environment. , As novel cocatalysts in photocatalysis, SACs cooperatively work with semiconducting photocatalysts, achieving spatial charge separation and boosting photocatalytic performance. For HER, Pt is the most broadly studied cocatalyst due to its relatively large work function accepting photoexcited electrons and low overpotential for water reduction. − Recent studies demonstrated that Pd SAs outperform Pt SAs in terms of HER. − For instance, Schmuki and co-workers loaded different noble metal SAs (Pd, Pt, and Au) onto anatase titanium dioxide (TiO 2 ) nanosheets and compared their HER efficiency .…”

Atomic Engineering of Single‐Atom Nanozymes for Biomedical Applications

“…[13] The nature of the carrier, the unique active center's electronic symphony, and the coordination environment can greatly influence the chemical state and coordination structure of the metal single atoms, [14] and even regulate the adsorption and desorption behaviors of the reactants or products in the catalytic reaction to affect their enzyme-like activities. [15] Therefore, a more comprehensive understanding and regulation of the carrier types, local coordination microenvironment, and active centers of SACs can help to develop a new generation of nano-enzymatic materials for various biomedical applications (Figure 1). [16] First, Figure 1 illustrates that SAzyme can be rationally designed according to the structure of SAzyme by adjusting the carrier, the coordination environment of the first/second shell layer, and the metal active site to control the reactivity of SAzymes; in addition, Figure 1 illustrates the application of SAzyme in biosensing, tumor therapy, antibacterial, and anti-inflammatory therapies according to different development mechanisms.…”

Unraveling Intrinsic Electronic Factors in Thermocatalytic (Hemi-)Hydrogenation of Ethylene and Acetylene with Electric Polarization

“…Meanwhile, the interfacial sites between the metal nanoparticles and the support are highly support dependent and in many cases are the most catalytically active, − e.g., the interfacial Pt–Nb alloy sites on Pt/Nb 2 CT x MXene have been reported to enhance the kinetics of the water–gas shift reaction . Deconvolution of the electronic effect on metal catalysis from the chemical effect specific to the support material is often a topic of discussion in the literature. ,,− In this regard, non-Faradaic electrochemical modification of catalytic activity (NEMCA), initially proposed by Huggins, Mason, and co-workers and later developed by Vayenas and co-workers, , offers a conceptually straightforward method to isolate the effect of the Fermi level of metals on catalytic performance.…”