The Progress and Outlook of Metal Single-Atom-Site Catalysis

Abstract

Single-atom-site catalysts (SASCs) featuring maximized atom utilization and isolated active sites have progressed tremendously in recent years as a highly prosperous branch of catalysis research. Varieties of SASCs have been developed that show excellent performance in many catalytic applications. The major goal of SASC research is to establish feasible synthetic strategies for the preparation of high-performance catalysts, to achieve an in-depth understanding of the active-site structures and catalytic mechanisms, and to develop practical catalysts with industrial value. This Perspective describes the up-to-date development of SASCs and related catalysts, such as dual-atom-site catalysts (DASCs) and nano-single-atom-site catalysts (NSASCs), analyzes the current challenges encountered by these catalysts for industrial applications, and proposes their possible future development path.

Atomic Replacement of PtNi Nanoalloys within Zn-ZIF-8 for the Fabrication of a Multisite CO2 Reduction Electrocatalyst

“…Heterogeneous metal catalysts play a vital role in industrial chemical production, environmental protection, and sustainable energy generation. − To achieve efficient utilization of catalytically active metals, the metal species are generally designed to be highly dispersed forms such as metal nanoparticles, nanoclusters, and single atoms on a solid support . Among them, single-atom site catalysts (SASCs) have attracted particular attention owing to the almost 100% metal dispersion and unique geometric and electronic structures. − These structural characteristics endow SASCs with enhanced catalytic activities and even unprecedented catalytic properties compared with their nanoparticle counterparts. − However, ultrasmall-sized metal species including single atoms may not remain intact at elevated temperature or during the catalytic reaction, which can lead to unpredictable catalytic behavior changes.…”

Engineering the Electronic Structure of Single‐Atom Iron Sites with Boosted Oxygen Bifunctional Activity for Zinc–Air Batteries

“…The development of advanced energy conversion and storage technologies is important to fulfill the purpose of clean energy Single-atom catalysts (SACs), by virtue of their well-defined atomic structure, maximal metal utilization, unique electronic/ geometric properties, and excellent activity and selectivity, have attracted considerable research attention. [17][18][19][20][21][22][23][24][25][26] Nitrogen-doped carbon (NC) supported transition metal-based SACs, which exhibit the merits of good electrical conductivity, low cost, environmental friendliness, and comparable catalytic activity with precious-metal counterparts, have been regarded as one of the potentially feasible alternatives to precious-metal-based electrocatalysts in ORR and OER. [27][28][29][30] For example, Chen et al reported a polymerization-pyrolysis-evaporation strategy to synthesize N-doped porous carbon with atomically dispersed Fe 1 -N 4 sites.…”

“…[33] It exhibited impressive bifunctional oxygen electrocatalytic performance with an activity ΔE of merely 0.79 V. Nevertheless, further improvement in oxygen bifunctional electrocatalytic activity is still required to meet the real-life demands in energy storage systems. [20,34,35] In general, increasing the metal loading with a high number of exposed metal sites and optimizing the corresponding electronic structure are two important tactics to improve the intrinsic activity of electrocatalysts. [36][37][38][39] One grand challenge faced by NC-supported SACs is that when a high number of metal precursors are used but without a proper modification to the synthetic methods, these atomically dispersed metal sites tend to aggregate into large nanoclusters during pyrolysis, which is detrimental to electrocatalytic activity.…”

“…[36][37][38][39] One grand challenge faced by NC-supported SACs is that when a high number of metal precursors are used but without a proper modification to the synthetic methods, these atomically dispersed metal sites tend to aggregate into large nanoclusters during pyrolysis, which is detrimental to electrocatalytic activity. [19,20] Another challenge is ensuring the maximal exposure of metal sites in a 3D NC matrix, with negligible numbers of metal sites being buried inside and inaccessible, to significantly minimize the mass transport effects. [28,37,40,41] Furthermore, engineering the electronic structure of metal sites by tuning coordination environments can further optimize the adsorption/desorption of oxygen intermediates to effectively enhance the kinetics and activity of SACs.…”

“…[28,37,40,41] Furthermore, engineering the electronic structure of metal sites by tuning coordination environments can further optimize the adsorption/desorption of oxygen intermediates to effectively enhance the kinetics and activity of SACs. [20,34,42] Therefore, creating an efficient approach to simultaneously expose high-density active sites and precisely tune the electronic structure in SACs is required to endow excellent bifunctional ORR and OER performance in rechargeable zinc-air batteries. Meeting these design requirements is the main goal of this paper.…”