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Photocatalysts with different morphologies and specific exposed facets usually exhibit distinguished activities. Previous researches have focused on revealing the essence of the facet effect in photocatalysis; however, quantitative analyses on the differences of carrier dynamic between different facets are scarce. Herein, we successfully synthesized WO nanosheets and nanowires with dominant exposed facets of {001} and {110}, respectively. The lower hole effective mass on {110} (0.94 m) than on {001} (1.28 m) calculated by density functional theory leads to the higher hole mobility on {110} (4.92 cm V s) than on {001} (3.14 cm V s). Combined with the Einstein equation and the lifetime of the hole, the calculated hole diffusion length on {110} (74.8 nm) is larger than on {001} (53.4 nm). Overall, the lower hole effective mass, higher hole mobility, and greater hole diffusion length on {110} collectively result in a photocatalytic activity on benzyl alcohol oxidation 2.46 times as high as that on {001}.

Single‐atomic‐site (SAS) catalysts, a new frontier of catalysts, always show extremely high atom efficiency and unexpected catalytic properties. Herein, a pyrolyzing coordinated polymer (PCP) strategy is developed, which is facile and widely applicable in the synthesis of a series of SAS catalysts including SAS‐Fe, SAS‐Ni, SAS‐Cu, SAS‐Zn, SAS‐Ru, SAS‐Rh, SAS‐Pd, SAS‐Pt, and SAS‐Ir. The as‐obtained SAS catalysts can be easily synthesized at gram scale and the metal loading of SAS‐Fe catalysts achieves a record value of 30 wt%, which meets the requirement of practical applications. Moreover, it is discovered that SAS‐Fe catalysts show unprecedented catalytic performance for epoxidation of styrene using O2 as the only oxidant (yield: 64%; selectivity: 89%), while Fe nanoparticles and ironporphyrin are inactive. This discovery is believed to pave the way for exploiting the unparalleled properties of SAS catalysts and promoting their industrial applications.

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atoms in SACs are chemically bonded to elements on the supports. This unique structural characteristic endows SACs with strong metal support interactions (SMSIs) [6][7][8][9][10] and tailorable homogenized active metal sites. [11][12][13][14] SACs have been found to be very favorable in many fields, including electrocatalysis, [15][16][17][18] organocatalysis, [19][20][21] industrial catalysis, [22][23][24] and others. [25][26][27][28][29][30] Consequently, revealing the atomic structure of the central metal atoms and the SMSI in SACs has become an important subject of research because it provides possibilities for rational design of novel SACs for specific reactions. The recent development of advanced characterization techniques, including aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM), scanning tunneling microscopy images, extended X-ray absorption fine structure (EXAFS) curve fitting, and DFT modeling, provide crucial tools for identifying the atomic structure. [31][32][33][34][35][36][37] Meanwhile, tremendous efforts have been devoted to exploring SMSIs in SACs and their relationship with catalytic properties. [38][39][40][41] However, a systematic understanding of SMSIs Recognizing and controlling the structure-activity relationships of singleatom catalysts (SACs) is vital for manipulating their catalytic properties for various practical applications. Herein, Fe SACs supported on nitrogen-doped carbon (SA-Fe/CN) are reported, which show high catalytic reactivity (97% degradation of bisphenol A in only 5 min), high stability (80% of reactivity maintained after five runs), and wide pH suitability (working pH range 3-11) toward Fenton-like reactions. The roles of different N species in these reactions are further explored, both experimentally and theoretically. It is discovered that graphitic N is an adsorptive site for the target molecule, pyrrolic N coordinates with Fe(III) and plays a dominant role in the reaction, and pyridinic N, coordinated with Fe(II), is only a minor contributor to the reactivity of SA-Fe/CN. Density functional theory (DFT) calculations reveal that a lower d-band center location of pyrrolic-type Fe sites leads to the easy generation of Fe-oxo intermediates, and thus, excellent catalytic properties.

Porous CoNC catalysts with ultrahigh surface area are highly required for catalytic reactions. Here, a scale-up method to synthesize gram-quantities of isolated Co single-site catalysts anchored on N-doped porous carbon nanobelt (Co-ISA/CNB) by pyrolysis of biomass-derived chitosan is reported. The usage of ZnCl 2 and CoCl 2 salts as effective activation-graphitization agents can introduce a porous belt-like nanostructure with ultrahigh specific surface area (2513 m 2 g −1 ) and high graphitization degree. Spherical aberration correction electron microscopy and X-ray absorption fine structure analysis reveal that Co species are present as isolated single sites and stabilized by nitrogen in CoN 4 structure. All these characters make Co-ISA/CNB an efficient catalyst for selective oxidation of aromatic alkanes at room temperature. For oxidation of ethylbenzene, the Co-ISA/CNB catalysts yield a conversion up to 98% with 99% selectivity, while Co nanoparticles are inert. Density functional theory calculations reveal that the generated CoO centers on isolated Co single sites are responsible for the excellent catalytic efficiency.

The active species in supported metal catalysts are elusive to identify, and large quantities of inert species can cause significant waste. Herein, using a stoichiometrically precise synthetic method, we prepare atomically dispersed palladium-cerium oxide (Pd /CeO ) and hexapalladium cluster-cerium oxide (Pd /CeO ), as confirmed by spherical-aberration-corrected transmission electron microscopy and X-ray absorption fine structure spectroscopy. For aerobic alcohol oxidation, Pd /CeO shows extremely high catalytic activity with a TOF of 6739 h and satisfactory selectivity (almost 100 % for benzaldehyde), while Pd /CeO is inactive, indicating that the true active species are single Pd atoms. Theoretical simulations reveal that the bulkier Pd clusters hinder the interactions between hydroxy groups and the CeO surface, thus suppressing synergy of Pd-Ce perimeter.