General Design Concept for Single‐Atom Catalysts toward Heterogeneous Catalysis

Abstract

state of the catalyst, it can be classified as three types: homogeneous catalyst, heterogeneous catalyst, and biological (enzyme) catalyst. [4,5] Among them, the heterogeneous catalyst is the most important one because of its strong stability under severe conditions (e.g., high temperature, high pressure) and easy recovery from the reactants and products. [6,7] Heterogeneous catalyst is usually in the form of welldispersed metal particles and clusters, each of which may have multiple active sites with different properties. [8] It is well known that the coordination environment and electronic structure of metal-centered sites are the decisive factors in affecting the catalytic performance. However, traditional heterogeneous catalysts usually suffer from the insufficient utilization of atom, because only a small fraction of surface metal atoms can participate in the reaction. To reduce the cost of heterogeneous catalysis and improve the utilization efficiency of active metals in the heterogeneous catalyst, to rationally design and develop catalytic materials with good activity, durability and selectivity is now of greatest concern.Last decades, the gradual development of various precision instruments and detection methods has greatly stimulated the interests in the observation and exploration of microcosms. [9][10][11][12][13][14][15][16][17][18] Therefore, nanocatalysis, a new era of catalytic research, has been introduced and promoted by the rapid development of nanoscience. Studies have shown that the performance of catalyst can be determined by the size of catalytic metal particles. By controlling the nucleation and growth processes at nanoscale, nanoparticles (NPs) with high surface-to-volume ratios can be obtained. [19][20][21][22][23] Moreover, the abundant coordination unsaturated surface atoms located at edges, corners, and steps along with specific morphology of nanoparticles both have an important effect on the adsorption, desorption and activation process of small molecule reactants, which can effectively modulate the catalytic efficiency. [24] To obtain high atomic utilization efficiency, the particle of active metal is continuously reduced from nanoscale to sub-nanometer-scale or even atomic scale. [25,26] To this end, single-atom catalysts (SACs) bring new opportunities to the study in molecularly and atomically catalytic mechanisms, which require the accurate structure design at atomic scale.Compared with NPs catalysts, the metal species of SACs are uniformly dispersed on the support with maximum atom dispersion. [5,7,[27][28][29] Furthermore, the catalytic activities As a new and popular material, single-atom catalysts (SACs) exhibit excellent activity, selectivity, and stability for numerous important reactions, and show great potential in heterogeneous catalysis due to their high atom utilization efficiency and the controllable characteristics of the active sites. The composition and coordination would determine the geometric and electronic structures of SACs, and thus greatly influence the catal...

Synergy of Pd atoms and oxygen vacancies on In2O3 for methane conversion under visible light

“…Stimulated by molecular catalysis, single atom cocatalysts promise an extremely high efficiency, where atomic dispersed species with unsaturated coordination environment could improve the catalytic performances based on the unique electronic structure 43 – 45 . Meanwhile, high atom utilization efficiency could be achieved 46 , 47 . On the other hand, since CH 4 exhibited low electron and proton affinity, moderate decoration of defective sites could enhance the chemical-adsorption of non-polar molecular, then promoting the activation of CH 4 48 .…”

Atomically Defined Undercoordinated Copper Active Sites over Nitrogen‐Doped Carbon for Aerobic Oxidation of Alcohols

“…[12] As a new frontier, single atom catalysts (SACs) have gained wide attention because of their great advantages of high atom efficiency and unique catalytic activity. [13][14][15][16][17][18][19][20] SACs possess distinctive chemical and physical properties and a unique coordination environment that is different from their nanoparticle counterparts. [21][22][23][24][25] Moreover, SACs have been found to be effective in bridging homogeneous and heterogeneous catalysis.…”

Single-atom-based catalysts for photoelectrocatalysis: challenges and opportunities

“…18 The rational design of SACs can offer favorable congurations and advantageous adsorption energy of chemisorbed molecules on single-atom active sites, to further improve the catalytic activity and selectivity of PEC. 43 Promoted charge separation and transfer Anchored or coordinated with the support, single metal atoms can form strong interactions with their support. 44 The metalsupport interaction arises with the orbital rehybridization and charge transfer across the interface.…”