Synthesis of Single-Atom Catalysts Through Top-Down Atomization Approaches

Abstract

Single-atom catalysts (SACs) have emerged as a hot research topic in recently years, and have been intensively investigated for energy storage and conversion applications. Significant advances in the synthesis of SACs have been achieved through enormous efforts in this area, however, their application is hindered by the low active site loading and poor long-term stability. In contrast with other methods, atomization, in which the SACs are synthesized from transformation of the nanoparticles to atomic sites, is a very attractive and innovative top-down approach to achieve high-density supported active sites with outstanding stability. However, limited attention has been paid to this area, despite the significant advances achieved in the past two years. In this short review, we discuss in detail the latest advances in atomization approaches for the synthesis of SACs and highlight the associated advantages and opportunities.

Cobalt-Based Cathode Catalysts for Oxygen-Reduction Reaction in an Anion Exchange Membrane Fuel Cell

“…To localize the single cobalt atom [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ] which is expressed in CoNx bonding in the carbon matrix, HRTEM pictures taken from Figure 5 a at two selected sites (sites 1 and 2) are shown in Figure 5 b,d, respectively. Many CoNx dots are dispersed around Co crystalline in Figure 5 b and the electron diffraction pattern which is also demonstrated in Figure 5 c. From the HRTEM micrograph revealed in Figure 5 d, the Co(111) and C(002) planes are identified, and the electron diffraction pattern of the Co crystalline is illustrated in Figure 5 e.…”

“…To localize the single cobalt atom [23][24][25][26][27][28][29][30][31][32][33][34][35][36] which is expressed in Co carbon matrix, HRTEM pictures taken from Figure 5a at two selected s…”

“…The embedded Co metal or CoO inside CoNC-1000A-900 can also be found in Figure 4f or Figure 4g. To localize the single cobalt atom [23][24][25][26][27][28][29][30][31][32][33][34][35][36] which is expressed in CoNx bonding in the carbon matrix, HRTEM pictures taken from Figure 5a at two selected sites (sites 1 and 2) are shown in Figure 5b,d, respectively. Many CoNx dots are dispersed around Co crystalline in Figure 5b and the electron diffraction pattern which is also demonstrated in Figure 5c.…”

Engineering at Subatomic Scale: Achieving Selective Catalytic Pathways via Tuning of the Oxidation States in Functionalized Single‐Atom Quantum Catalysts

“…Therefore, most of the time the synthesis of SACs is carried out under inert atmospheres (Ar or N 2 ). [ 18 ] Another factor that is to be considered is the type of support on which single atoms are stabilized. One successful attempt of altering the oxidation states in a SAC utilizing this strategy was achieved via alteration of the Pt coordination environments with oxygen atoms on CeO 2 support in order to attenuate the electron dynamics over the metal/CeO 2 surface.…”

Scalable Synthesis of Pt Nanoflowers on Solution‐Processed MoS2 Thin Film for Efficient Hydrogen Evolution Reaction

“…[9b,10] Atom-scale defects on these support materials such as oxygen vacancies, unsaturated coordination sites, and heteroatom dopants serve as anchoring sites on which platinum atoms can bind to. Although the single-atom platinum catalysts allow for significant enhancement in the catalytic activity compared to the platinum nanoparticles on a per atom basis, [9a] their practical application in electrochemical water splitting is hindered because 1) scalable production of finely distributed defect sites at high densities is still challenging; [11] 2) the catalyst loading needs to be kept low (typically < 1 wt%) to ensure atomic dispersion of platinum without nanoparticle formation, which often leads to a low electrochemical activity per unit electrode area; [12] and 3) platinum atoms tend to detach from the anchoring sites and aggregate into nanoparticles during catalytic reaction. [11,13] Besides downsizing of the platinum catalysts, engineering of nanoscale particle morphology has also been intensively pursued to enhance the surface-to-volume ratio and the catalytic properties.…”