The classical strong metal–support interaction between TiO2 and IB metals was demonstrated.

No abstract

Synergistic effects have been discussed extensively in bimetallic heterogeneous catalysis, but it remains unclear how the effects function at the atomic scale. Here, we report a dual single-atom catalyst (DSAC) Ir1Mo1/TiO2 displaying much greater catalytic chemoselectivity (>96%, at 100% conversion) than comparable single-atom catalysts (SACs) Ir1/TiO2 (38%, at 87% conversion) and Mo1/TiO2 (no activity) for the hydrogenation of 4-nitrostyrene (4-NS) to 4-vinylaniline (4-VA). Activation of the TiO2-supported bimetallic carbonyl cluster Ir2Mo2(CO)10(η5-C5H5)2 in an Ar atmosphere affords the DSAC Ir1Mo1/TiO2. Characterization of the dual single-atom structure confirms that it consists of well-dispersed Ir single atoms (Ir1) and Mo single atoms (Mo1) on TiO2. Density functional theory studies reveal that Ir1 sites effect H2 activation while Mo1 sites are responsible for 4-NS adsorption, with synergistic cooperation between the two sets of single atoms contributing to the better catalytic performance for the hydrogenation of 4-NS. This work provides a deep understanding of synergistic effects in dual single-atom catalysis.

No abstract

Size matters: Gold clusters (<2.0 nm), but not gold nanoparticles, deposited on alkaline‐treated titanosilicalite‐1 allow O2 and H2O to react to give hydroperoxides (‐OOH). These transfer to neighboring Ti sites to form Ti‐OOH (see scheme), which is responsible for propene epoxidation to give propene epoxide (PO).

The solvent-free selective oxidation of alcohols to aldehydes with molecular oxygen is highly attractive yet challenging. Interfacial sites between a metal and an oxide support are crucial in determining the activity and selectivity of such heterogeneous catalysts. Herein, we demonstrate that the use of supported single-atom catalysts (SACs) leads to high activity and selectivity in this reaction. The significantly increased number of interfacial sites, resulting from the presence of individually dispersed metal atoms on the support, renders SACs one or two orders of magnitude more active than the corresponding nanoparticle (NP) catalysts. Lattice oxygen atoms activated at interfacial sites were found to be more selective than O activated on metal NPs in oxidizing the alcohol substrate. This work demonstrates for the first time that the number of interfacial sites is maximized in SACs, providing a new avenue for improving catalytic performance by developing appropriate SACs for alcohol oxidation and other reactions occurring at metal-support interfacial sites.

This study was to estimate the prevalence and characteristics of Staphylococcus aureus from 1,850 retail meat and meat products in China during July 2011 to June 2016. The samples were collected covering most provincial capitals in China, including 604 raw meat, 601 quick-frozen meat, and 645 ready-to-eat meat. Using the qualitative and quantitative methods, all 39 cities had S. aureus-positive samples, and S. aureus was detected in 35.0% (647/1,850) of the samples. The levels of S. aureus in retail meat showed that the MPN value of the majority of the positive samples ranged from 0.3 to 100 MPN/g. Twenty-four antibiotics were used to test all 868 S. aureus isolates for antibiotic susceptibility. Only 11 isolates (1.26%) were susceptible to all antibiotics, whereas most isolates (821/868, 94.6%) showed resistance or intermediary resistance to more than three or more antibiotics. Of these strains, 104 (12.0%) were resistant to more than 10 antibiotics. However, the most frequent resistance was observed to ampicillin (85.4%), followed by penicillin (84.6%), erythromycin (52.7%), tetracycline (49.3%), kanamycin (45.3%), telithromycin (30.1%), clindamycin (29.6%), streptomycin (21.1%), norfloxacin (20.4%), gentamicin (19.4%), fusidic acid (18.4%), ciprofloxacin (16.9%), chloramphenicol (13.1%), amoxycillin/clavulanic acid (11.0%), and others (<10%). 7.4% of isolates (62/868) were confirmed as methicillin-resistance S. aureus (MRSA). By molecular typing analysis, there were 164 spa types and 111 STs were identified, including 15 novel spa types and 65 newly STs by multilocus sequence typing (MLST) and spa typing. Despite the wide genetic diversity observed among the 868 isolates, a great proportion of the population belonged to finite number of major clones: ST1-t127 (93/868, 10.7%) and ST7-t091 (92/868, 10.6%), ST5-t002 (42/868, 4.8%), ST398-t034 (40/868, 4.6%), ST188-t034 (38/868, 4.4%), ST59-t437 (30/868, 3.5%), ST6-t701 (29/868, 3.3%), and ST9-t899 (27/868, 3.1%) in China. This study reflects S. aureus was readily detected in Chinese retail meat and meat products but the level were not very excessive. In this study, the high antibiotic resistance is alarming and raising public health concern. In additions, most of molecular types of isolates have been linked to human infections around the world, indicating that these types of S. aureus in China have a theoretical pathogenic potential.

Atomic substitutions at the tetrahedral site (ATd) could theoretically achieve an efficient optimization of the charge at the octahedral site (BOh) through the ATd‐O‐BOh interactions in the spinel oxides (AB2O4). Despite substantial progress having been made, the precise control and adjustment of the spinel oxides are still challenging owing to the complexity of their crystal structure. In this work, we demonstrate a simple solvent method to tailor the structures of spinel oxides and use the spinel oxide composites (ACo2O4/NCNTs, A=Mn, Co, Ni, Cu, Zn) for oxygen electrocatalysis. The optimized MnCo2O4/NCNTs exhibit high activity and excellent durability for oxygen reduction/evolution reactions. Remarkably, the rechargeable liquid Zn–air battery equipped with a MnCo2O4/NCNTs cathode affords a specific capacity of 827 mAh gZn−1 with a high power density of 74.63 mW cm−2 and no voltage degradation after 300 cycles at a high charging–discharging rate (5 mA cm−2). The density functional theory (DFT) calculations reveal that the substitution could regulate the ratio of Co3+/Co2+ and thereby lead to the modulation of the electronic structure accompanied with the movement of the d‐band center. The tetrahedral and octahedral sites interact through the Mn−O−Co, and the Co3+Oh of MnCo2O4 with the optimal charge structure allows a more suitable binding interaction between the active center and the oxygenated species, resulting in superior oxygen electrocatalytic performance.