Single‐Atom Catalysts: Emerging Multifunctional Materials in Heterogeneous Catalysis

Abstract

Supported metal nanoparticles are the most widely investigated heterogeneous catalysts in catalysis community. The size of metal nanostructures is an important parameter in influencing the activity of constructed catalysts. Especially, as coordination unsaturated metal atoms always work as the catalytically active centers, decreasing the particle size of the catalyst can greatly boost the specific activity per metal atom. Single‐atom catalysts (SACs), containing single metal atoms anchored on supports, represent the utmost utilization of metallic catalysts and thus maximize the usage efficiency of metal atom. However, with the decreasing of particle size, the surface free energy increases obviously, and tends to aggregate into clusters or particles. Selection of an appropriate support is necessary to interact with isolated atoms strongly, and thus prevents the movement and aggregation of isolated atoms, creating stable, finely dispersed active sites. Furthermore, with uniform single‐atom dispersion and well‐defined configuration, SACs afford great space for optimizing high selectivity and activity. In this review, a detailed discussion of preparing, characterizing, and catalytically testing within this family is provided, including the theoretical understanding of key aspects of SACs materials. The main advantages of SACs as catalysts and the challenges faced for further improving catalytic performance are also highlighted.

Atomically Dispersed Molybdenum Catalysts for Efficient Ambient Nitrogen Fixation

“…[1][2][3][4] From an energy-saving perspective,g reen N 2 to NH 3 fixation methods are strongly desired because the main industrial process for producing NH 3 -the Haber-Bosch process-requires extremely harsh reaction conditions (400-600 8 8C, 20-40 MPa) and causes pollution and greenhouse gas emissions. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However,t he efficiency of the NRR suffers from ap arallel hydrogen evolution reaction (HER) in aqueous solutions on traditional NRR electrocatalysts. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However,t he efficiency of the NRR suffers from ap arallel hydrogen evolution reaction (HER) in aqueous solutions on traditional NRR electrocatalysts.…”

“…An otable example involves the Bi 4 V 2 O 11 /CeO 2 hybrid for producing NH 3 ,w here the highest FE and NH 3 yield rate achieved were 10.16 %a nd 23.21 mgh À1 mg cat. [27] It has been established that metal atoms with unsaturated coordination sites are likely to be the active catalytic centers. [20] Metal-free catalysts,s uch as boron carbide, [23] porous carbon, [24] and their derivatives, [25,26] are alternative materials,o fw hich boron carbide (B 4 C) nanosheets presented the highest FE of 15.95 %a nd ac orresponding NH 3 yield rate of 26.57 mgh À1 mg À1 cat .…”

“…À1 ,r espectively. [27] Therefore,when optimizing catalysts it is highly desirable to simultaneously decrease the size of ac atalyst and increase the fraction of metal atoms with unsaturated coordination sites.O nt he basis of this aspect, atomically dispersed catalysts with mononuclear non-precious-metal complexes or single non-precious-metal atoms anchored on supports would be ap romising candidate for NRR catalysts because of their maximum atom efficiency, unique catalytic performances,a nd unsaturated metal coordination environment. [23] These significant discoveries guide the scientific community to development of cost-effective and high-performance NRR electrocatalysts for achieving high FE and NH 3 yield rates in aqueous solution under ambient conditions.…”

Ultrasmall MoOx Clusters as a Novel Cocatalyst for Photocatalytic Hydrogen Evolution

“…Fu and colleagues have integrated CdS with MoS 2 and obtained much improved hydrogen evolution activity. [25,26] Herein, a bottom-up strategy is developed to decorate ultrasmall molybdenum-oxygen (MoO x ) clusters onto the surface of CdS nanowires (NWs). [18][19][20] Thus, designing novel materials which can address these problems may lead to the discovery of non-noble metal cocatalysts with enhanced performance.…”

Modulierung der elektronischen Strukturen anorganischer Nanomaterialien für eine effiziente elektrokatalytische Wasserspaltung

“…[11,12,19,72] Die Elektronenpolarisierung an der Dotierungsstelle kçnnte die Elektronenaffinitäts owohl der dotierenden Metallatome als auch der ursprünglichen Nichtmetallatome abstimmen und hierdurch die Reaktionskinetik des Ladungstransfers in Nachbarschaft zur Dotierungsstelle verbessern. [11,12,19,72] Die Elektronenpolarisierung an der Dotierungsstelle kçnnte die Elektronenaffinitäts owohl der dotierenden Metallatome als auch der ursprünglichen Nichtmetallatome abstimmen und hierdurch die Reaktionskinetik des Ladungstransfers in Nachbarschaft zur Dotierungsstelle verbessern.…”