Functional CeOx nanoglues for robust atomically dispersed catalysts.

Single-atom catalysts1 make exceptionally efficient use of expensive noble metals and can bring out unique properties1-3. However, applications are usually compromised by limited catalyst stability, which is due to sintering3,4. Although sintering can be suppressed by anchoring the metal atoms to oxide supports1,5,6, strong metal-oxygen interactions often leave too few metal sites available for reactant binding and catalysis6,7, and when exposed to reducing conditions at sufficiently high temperatures, even oxide-anchored single-atom catalysts eventually sinter4,8,9. Here we show that the beneficial effects of anchoring can be enhanced by confining the atomically dispersed metal atoms on oxide nanoclusters or 'nanoglues', which themselves are dispersed and immobilized on a robust, high-surface-area support. We demonstrate the strategy by grafting isolated and defective CeOx nanoglue islands onto high-surface-area SiO2; the nanoglue islands then each host on average one Pt atom. We find that the Pt atoms remain dispersed under both oxidizing and reducing environments at high temperatures, and that the activated catalyst exhibits markedly increased activity for CO oxidation. We attribute the improved stability under reducing conditions to the support structure and the much stronger affinity of Pt atoms for CeOx than for SiO2, which ensures the Pt atoms can move but remain confined to their respective nanoglue islands. The strategy of using functional nanoglues to confine atomically dispersed metals and simultaneously enhance their reactivity is general, and we anticipate that it will take single-atom catalysts a step closer to practical applications.

Efficient Interfacial Sites between Metallic and Oxidized Cobalt for Propene Hydroformylation.

Currently, the hydroformylation of short olefins is operated almost exclusively by using Rh catalysts. Considering the high cost and scarcity of rhodium resources, it is important to develop non-noble metal catalysts toward hydroformylation. Herein, we report an efficient cobalt-based catalyst rich in interfacial sites between metallic and oxidized cobalt species for the hydroformylation of short olefin, propene, under a moderate syngas pressure. The catalyst exhibited a high specific activity of 252 mol molCo-1 h-1 in toluene under 2 bar of propene and 40 bar of CO/H2 mixed gas (CO/H2 = 1:1) at 160 °C. According to mechanistic studies, the interface of metallic and oxidized cobalt species promoted the adsorption of CO and propene. Moreover, the interfacial sites lowered the energy barrier for CO* hydrogenation and C-C coupling compared with metallic cobalt.

Bipyridine-Confined Silver Single-Atom Catalysts Facilitate In-Plane C-O Coupling for Propylene Electrooxidation.

The electrooxidation of propylene presents a promising route for the production of 1,2-propylene glycol (PG) under ambient conditions. However, the C-O coupling process remains a challenge owing to the high energy barrier. In this work, we developed a highly efficient electrocatalyst of bipyridine-confined Ag single atoms on UiO-bpy substrates (Ag SAs/UiO-bpy), which exposed two in-plane coordination vacancies during reaction for the co-adsorption of key intermediates. Detailed structure and electronic property analyses demonstrate that CH3CHCH2OH* and *OH could stably co-adsorb in a square planar configuration, which then accelerates the charge transfer between them. The combination of stable co-adsorption and efficient charge transfer facilitates the C-O coupling process, thus significantly lowering its energy barrier. At 2.4 V versus a reversible hydrogen electrode, Ag SAs/UiO-bpy achieved a record-high activity of 61.9 gPG m-2 h-1. Our work not only presents a robust electrocatalyst but also advances a new perspective on catalyst design for propylene electrooxidation.

Comparison of influenza- and COVID-19-associated pulmonary aspergillosis in China.

PURPOSE: We conducted a monocentric retrospective study using the latest definitions to compare the demographic, clinical, and biological characteristics of influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA). METHODS: The study retrospectively enrolled 180 patients, including 70 influenza/IPA patients (with positive influenza A/B and Aspergillus) and 110 COVID-19/IPA patients (with positive SARS-CoV-2 and Aspergillus). Among them, 42 (60%) and 30 (27.3%) patients fulfilled the definitions of IAPA and CAPA, respectively. RESULTS: The CAPA patients had significantly higher in-hospital mortality (13/31, 41.9%) than IAPA patients (8/42, 19%) with a P-value of 0.033. Kaplan-Meier survival curve also showed significantly higher 30-day mortality for CAPA patients (P = 0.025). Additionally, the CAPA patients were older, though insignificantly, than IAPA patients (70 (60-80) vs. 62 (52-72), P = 0.075). A lower percentage of chronic pulmonary disease (12.9 vs. 40.5%, P = 0.01) but higher corticosteroids use 7 days before and after ICU admission (22.6% vs. 0%, P = 0.002) were found in CAPA patients. Notably, there were no significant differences in the percentage of ICU admission or ICU mortality between the two groups. In addition, the time from observation to Aspergillus diagnosis was significantly longer in CAPA patients than in IAPA patients (7 (2-13) vs. 0 (0-4.5), P = 0.048). CONCLUSION: Patients infected with SARS-CoV-2 and Aspergillus during the concentrated outbreak of COVID-19 in China had generally higher in-hospital mortality but a lower percentage of chronic pulmonary disease than those infected with influenza and Aspergillus. For influenza-infected patients who require hospitalization, close attention should be paid to the risk of invasive aspergillosis upfront.

The Importance of Sintering-Induced Grain Boundaries in Copper Catalysis to Improve Carbon-Carbon Coupling.

Syngas conversion serves as a gas-to-liquid technology to produce liquid fuels and valuable chemicals from coal, natural gas, or biomass. During syngas conversion, sintering is known to deactivate the catalyst owing to the loss of active surface area. However, the growth of nanoparticles might induce the formation of new active sites such as grain boundaries (GBs) which perform differently from the original nanoparticles. Herein, we reported a unique Cu-based catalyst, Cu nanoparticles with in situ generated GBs confined in zeolite Y (denoted as activated Cu/Y), which exhibited a high selectivity for C5+ hydrocarbons (65.3 C%) during syngas conversion. Such high selectivity for long-chain products distinguished activated Cu/Y from typical copper-based catalysts which mainly catalyze methanol synthesis. This unique performance was attributed to the GBs, while the zeolite assisted the stabilization through spatial confinement. Specifically, the GBs enabled H-assisted dissociation of CO and subsequent hydrogenation into CHx*. CHx* species not only serve as the initiator but also directly polymerize on Cu GBs, known as the carbide mechanism. Meanwhile, the synergy of GBs and their vicinal low-index facets led to the CO insertion where non-dissociative adsorbed CO on low-index facets migrated to GBs and inserted into the metal-alkyl bond for the chain growth.

Dynamic Metal-Ligand Coordination Boosts CO2 Electroreduction.

The interfacial structure of heterogeneous catalysts determines the reaction rate by adjusting the adsorption behavior of reaction intermediates. Unfortunately, the catalytic performance of conventionally static active sites has always been limited by the adsorbate linear scaling relationship. Herein, we develop a triazole-modified Ag crystal (Ag crystal-triazole) with dynamic and reversible interfacial structures to break such a relationship for boosting the catalytic activity of CO2 electroreduction into CO. On the basis of surface science measurements and theoretical calculations, we demonstrated the dynamic transformation between adsorbed triazole and adsorbed triazolyl on the Ag(111) facet induced by metal-ligand conjugation. During CO2 electroreduction, Ag crystal-triazole with the dynamically reversible transformation of ligands exhibited a faradic efficiency for CO of 98% with a partial current density for CO as high as -802.5 mA cm-2. The dynamic metal-ligand coordination not only reduced the activation barriers of CO2 protonation but also switched the rate-determining step from CO2 protonation to the breakage of C-OH in the adsorbed COOH intermediate. This work provided an atomic-level insight into the interfacial engineering of the heterogeneous catalysts toward highly efficient CO2 electroreduction.

Dynamically Reversible Interconversion of Molecular Catalysts for Efficient Electrooxidation of Propylene into Propylene Glycol.

For the electrooxidation of propylene into 1,2-propylene glycol (PG), the process involves two key steps of the generation of *OH and the transfer of *OH to the C═C bond in propylene. The strong *OH binding energy (EB(*OH)) favors the dissociation of H2O into *OH, whereas the transfer of *OH to propylene will be impeded. The scaling relationship of the EB(*OH) plays a key role in affecting the catalytic performance toward propylene electrooxidation. Herein, we adopt an immobilized Ag pyrazole molecular catalyst (denoted as AgPz) as the electrocatalyst. The pyrrolic N-H in AgPz could undergo deprotonation to form pyrrolic N (denoted as AgPz-Hvac), which can be protonated reversibly. During propylene electrooxidation, the strong EB(*OH) on AgPz favors the dissociation of H2O into *OH. Subsequently, the AgPz transforms into AgPz-Hvac that possesses weak EB(*OH), benefiting to the further combination of *OH and propylene. The dynamically reversible interconversion between AgPz and AgPz-Hvac accompanied by changeable EB(*OH) breaks the scaling relationship, thus greatly lowering the reaction barrier. At 2.0 V versus Ag/AgCl electrode, AgPz achieves a remarkable yield rate of 288.9 mmolPG gcat-1 h-1, which is more than one order of magnitude higher than the highest value ever reported.

Molecular Characteristics of an NDM-4 and OXA-181 Co-Producing K51-ST16 Carbapenem-Resistant Klebsiella pneumoniae: Study of Its Potential Dissemination Mediated by Conjugative Plasmids and Insertion Sequences.

The carbapenem-resistant Klebsiella pneumoniae (CRKP) strain GX34 was recovered from the respiratory tract of an elderly male with severe pneumonia, and only susceptible to amikacin, tigecycline, and colistin. Complete genome suggested that it belonged to K51-ST16 and harbored plasmid-encoded NDM-4 and OXA-181, located on IncFIB plasmid GX34p1_NDM-4 and ColKP3/IncX3 plasmid GX34p4_OXA-181, respectively. A series of transconjugants generated in the plasmid conjugation assays, including Escherichia coli J53-N1 (harboring a self-transmissible and blaNDM-1-producing plasmid Eco-N-1-p), J53-N2 (harboring a blaNDM-4-producing plasmid and a helper plasmid GX34p5), and J53-O (harboring a blaOXA-181-producing plasmid), could be stably inherited after 10 days of serial passage and no significant biological fitness costs were detected. Furthermore, we first reported the blaNDM-1 gene, derived from blaNDM-4 mutation (460C>A) under meropenem pressure, could be in vitro transferred into a self-conjugative, recombined plasmid Eco-N-1-p of J53-N1. Eco-N-1-p was mainly recombined by GX34p4_OXA-181 (40,449 bp, 75.16%) and GX34p1_NDM-4 (8,553 bp, 15.89%), in which IS26 and IS5-like probably played a major role. Eco-N-1-p could be transferred into the conjugation recipient K. pneumoniae KP54 and make the latter sacrifice fitness. The retention rates of blaNDM-1 remained high stability (>80% after 200 generations). The comparative genomic analysis of GX34 and those carrying blaNDM-4 or blaOXA-181 genes retrieved from the NCBI RefSeq database showed all blaNDM-4 (26/26, 100.00%) and blaOXA-181 (13/13, 100.00%) were surrounded by IS26. The immediate environment of blaNDM-4 and blaOXA-181 in GX34 and some retrieved strains shared identical features, hinting at their possible dissemination. Effective measures should be taken to monitor the spread of this clone.

In vitro activity of cefiderocol, a siderophore cephalosporin, against carbapenem-resistant hypervirulent Klebsiella pneumoniae in China.

Cefiderocol is a siderophore cephalosporin that binds ferric iron and utilizes iron transporters to cross the cell membrane. Hypervirulent Klebsiella pneumoniae (hvKp) is known to produce more siderophores; in this case, the uptake of cefiderocol may be decreased. Therefore, the objective of this study was to evaluate the in vitro activity of cefiderocol against hvKp isolates. A total of 320 carbapenem-resistant K. pneumoniae (CRKp) isolates were collected in China between 2014 and 2022, including 171 carbapenem-resistant hvKp (CR-hvKp) and 149 carbapenem-resistant classical K. pneumoniae (CR-cKp). Quantitative detection of siderophores showed that the average siderophore production of CR-hvKp (234.6 mg/L) was significantly higher than that of CR-cKp (68.9 mg/L, P < 0.001). The overall cefiderocol resistance rate of CR-hvKp and CR-cKp was 5.8% (10/171) and 2.7% (4/149), respectively. The non-susceptible rates of both cefiderocol and siderophore production of CR-hvKp isolates were higher than those of CR-cKp in either NDM-1- or KPC-2-producing groups. The MIC90 and MIC50 for CR-hvKp and CR-cKp were 8 mg/L and 2 mg/L and 4 mg/L and 1 mg/L, respectively. The cumulative cefiderocol MIC distribution for CR-hvKp was significantly lower than that of CR-cKp isolates (P = 0.003). KL64 and KL47 consisted of 53.9% (83/154) and 75.7% (53/70) of the ST11 CR-hvKp and CR-cKp, respectively, and the former had significantly higher siderophore production. In summary, cefiderocol might be less effective against CR-hvKp compared with CR-cKp isolates, highlighting the need for caution regarding the prevalence of cefiderocol-resistant K. pneumoniae strains, particularly in CR-hvKp isolates.

Understanding the Effect of *CO Coverage on C-C Coupling toward CO2 Electroreduction.

Cu-based tandem nanocrystals have been widely applied to produce multicarbon (C2+) products via enhancing CO intermediate (*CO) coverage toward CO2 electroreduction. Nevertheless, it remains ambiguous to understand the intrinsic correlation between *CO coverage and C-C coupling. Herein, we constructed a tandem catalyst via coupling CoPc with the gas diffusion electrode of Cu (GDE of Cu-CoPc). A faradaic efficiency for C2+ products of 82% was achieved over a GDE of Cu-CoPc at an applied current density of 480 mA cm-2 toward CO2 electroreduction, which was 1.8 times as high as that over the GDE of Cu. Based on in situ experiments and density functional theory calculations, we revealed that the high *CO coverage induced by CO-generating CoPc promoted the local enrichment of *CO with the top adsorption mode, thus reducing the energy barrier for the formation of OCCO intermediate. This work provides an in-depth understanding of the surface coverage-dependent mode-specific C-C coupling mechanism toward CO2 electroreduction.

Symmetry-Breaking Sites for Activating Linear Carbon Dioxide Molecules.

ConspectusCO2 is not only a greenhouse gas but also a pivotal carbon source as a promising supplement to fossil fuels. Both the environment and energy crises have compelled the researchers to explore how to efficiently transform CO2 into liquid fuels and value-added chemicals. As the industrialized approach nowadays, heterogeneous CO2 hydrogenation driven by thermal energy represents a potential strategy to help mitigate the greenhouse effect and reduce the reliance on fossil fuels. However, as the prerequisite for CO2 hydrogenation, CO2 activation is difficult due to the thermodynamic stability and chemical inertness of CO2 molecules. It is not proper to activate CO2 by directly increasing the reaction temperature, because CO2 hydrogenation into liquid products is an exothermic process where elevating the temperature decreases both the balanced conversion of CO2 and the balanced selectivity for target products. Therefore, the key scientific issue for CO2 hydrogenation lies in how to design catalysts which enable efficient activation of CO2. Up to date, a vast variety of active sites have been constructed for effective activation of CO2. These active sites including step sites, alloys, interface, substitution, vacancies, etc. are generally symmetry-breaking rather than perfect flat surfaces.Herein, we propose a catalyst design principle of constructing symmetry-breaking sites to activate nonpolar CO2 molecules. From the perspective of electronic properties, there is a prominent charge density gradient in a symmetry-breaking center, resulting in perturbing electronic structures of nonpolar CO2 and polarizing the adsorbed species. From the perspective of adsorption configuration, a symmetry-breaking site gives a local torque which enables more effective overlapping of atomic orbitals and thus more facilely bending of linear CO2 molecules, compared with symmetric sites. In this Account, we categorize the modes of CO2 activation and put forward the design principle of constructing symmetry-breaking sites. Moreover, we illustrate how to construct symmetry-breaking sites from the perspectives of local and global structures. Strategies to break the symmetry of local structures include surface substitution, surface adatom, and surface vacancy. Strategies to break the symmetry of global structures comprise surface modification with ligands, high-index surface, and phase reconstruction. In the future, further improvements, such as quantified descriptors, function for C-C coupling, and applicability to other nonpolar molecules, are necessary.

Bias-Adaptable CO2-to-CO Conversion via Tuning the Binding of Competing Intermediates.

CO2 electroreduction powered by renewable electricity represents a promising method to enclose anthropogenic carbon cycle. Current catalysts display high selectivity toward the desired product only over a narrow potential window due primarily to unoptimized intermediate binding. Here, we report a functional ligand modification strategy in which palladium nanoparticles are encapsulated inside metal-organic frameworks with 2,2'-bipyridine organic linkers to tune intermediate binding and thus to sustain a highly selective CO2-to-CO conversion over widened potential window. The catalyst exhibits CO faradaic efficiency in excess of 80% over a potential window from -0.3 to -1.2 V and reaches the maxima of 98.2% at -0.8 V. Mechanistic studies show that the 2,2'-bipyridine on Pd surface reduces the binding strength of both *H and *CO, a too strong binding of which leads to competing formate production and CO poison, respectively, and thus enhances the selectivity and stability of CO product.

Pd-Pt Tesseracts for the Oxygen Reduction Reaction.

Hollow frame structures are of special interest in the realm of catalysis since they hold only ridges and hollow interiors, enabling the accessibility of active sites to the most extent. Herein, we prepared Pd-Pt hollow frame structures composed of double-shell cubes linked by body diagonals as an efficient catalyst toward the oxygen reduction reaction (ORR), inspired by the 4D analogue of a cube, denoted as a tesseract. The etching process involves the selective removal of Pd atoms and the subsequent rearrangement of the remaining Pd and Pt atoms. The successful preparation of Pd-Pt tesseracts via etching lies in the selection of Pd/Pt ratio in the initial Pd-Pt nanocubes. With various ratios of Pd-Pt nanocubes as templates, we obtained Pd-Pt octapods, tesseracts, and nanoframes, respectively. During the ORR, Pd-Pt tesseracts exhibited the highest mass activity of 1.86 A mg-1Pt among these Pd-Pt nanocrystals. On the basis of mechanistic studies, the high activity of Pd-Pt tesseracts derived from the optimal oxygen adsorption energy due to the facet effect and composition effect.

High-Throughput Single-Cell Cultivation on Microfluidic Streak Plates.

This paper describes the microfluidic streak plate (MSP), a facile method for high-throughput microbial cell separation and cultivation in nanoliter sessile droplets. The MSP method builds upon the conventional streak plate technique by using microfluidic devices to generate nanoliter droplets that can be streaked manually or robotically onto petri dishes prefilled with carrier oil for cultivation of single cells. In addition, chemical gradients could be encoded in the droplet array for comprehensive dose-response analysis. The MSP method was validated by using single-cell isolation of Escherichia coli and antimicrobial susceptibility testing of Pseudomonas aeruginosa PAO1. The robustness of the MSP work flow was demonstrated by cultivating a soil community that degrades polycyclic aromatic hydrocarbons. Cultivation in droplets enabled detection of the richest species diversity with better coverage of rare species. Moreover, isolation and cultivation of bacterial strains by MSP led to the discovery of several species with high degradation efficiency, including four Mycobacterium isolates and a previously unknown fluoranthene-degrading Blastococcus species.

Loss and gain of ceftazidime-avibactam susceptibility in a non-carbapenemase-producing K1-ST23 hypervirulent Klebsiella pneumoniae.

OBJECTIVES: This study aimed at revealing the underlying mechanisms of the loss and gain of ceftazidime-avibactam susceptibility in a non-carbapenemase-producing hypervirulent Klebsiella pneumoniae (hvKp). METHODS: Here we longitudinally recovered 3 non-carbapenemase-producing K1-ST23 hvKp strains at a one-month interval (KP29105, KP29499 and KP30086) from an elderly male. Antimicrobial susceptibility testing, whole genome sequencing, transcriptomic sequencing, gene cloning, plasmid conjugation, quantitative real-time PCR (qRT-PCR), and SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) were conducted. RESULTS: Among the 3 hvKp strains, KP29105 was resistant to the third- and fourth-generation cephalosporins, KP29499 acquired resistance to both ceftazidime-avibactam and carbapenems, while KP30086 restored its susceptibility to ceftazidime-avibactam, imipenem and meropenem but retained low-level resistance to ertapenem. KP29105 and KP29499 carried plasmid-encoded genes blaCTX-M-15 and blaCTX-M-71, respectively, but KP30086 lost both. Cloning of gene blaCTX-M-71 and conjugation experiment of blaCTX-M-71-carrying plasmid showed that the transformant and transconjugant were susceptible to ceftazidime-avibactam but had a more than 8-fold increase in MICs. Supplementation with an outer membrane permeabilizer could reduce the MIC of ceftazidime-avibactam by 32 folds, indicating that porins play a key role in ceftazidime-avibactam resistance. The OmpK35 of the 3 isolates was not expressed, and the OmpK36 of KP29499 and KP30086 had a novel amino acid substitution (L359R). SDS-PAGE and qRT-PCR showed that the expression of porin OmpK36 of KP29499 and KP30086 was significantly down-regulated compared with KP29105. CONCLUSIONS: In summary, we reported the rare ceftazidime-avibactam resistance in a non-carbapenemase-producing hvKp strain. Resistance plasmid carrying blaCTX-M-71 and mutated OmpK36 had a synergetic effect on the resistance.

Coexistence of virulent and multidrug-resistant plasmids in an uropathogenic Escherichia coli.

OBJECTIVES: The emergence of pathogens co-harbouring multiple mobile resistance and virulence elements is of great concern in clinical settings. Herein, we report an O101: H10-ST167 Escherichia coli Hu106 strain isolated from the urinary tract of a female in China. METHODS: Antibiotic susceptibility testing was used to present the antimicrobial resistance spectrum. Whole-genome sequencing (WGS) and bioinformatic analysis were used to clarify the virulent and resistance mechanisms. Furthermore, the virulence of this strain was tested by the Greater wax moth larvae and siderophore production experiment. RESULTS: The strain E. coli Hu106 was resistant to almost all antimicrobials tested, and only susceptible to aztreonam, amikacin, and tigecycline. WGS analysis revealed that the strain Hu106 co-harboured blaNDM-9 and mcr-1 on p2-Hu106, belonging to IncHI2/IncHI2A (256,000 bp). The co-existence of both resistance genes, blaNDM-9 and mcr-1, on the plasmid p2-Hu106 was mainly acquired by transposition recombination of mobile antibiotic elements mediated by IS26 and/or IS1 on IncHI2/IncHI2A type plasmid. In addition, the virulence clusters aerobactin (iutA-iucABCD) and salmochelin (iroBCDEN) were identified on an IncFIB/IncFIC(IncFII) type plasmid p1-Hu106, flanked by small mobile elements such as IS1A, ISkpn28, and IS3, respectively. After performing genomic comparison of p1-Hu106 with the WGS in NCBI, we identified that the virulent plasmid p1-Hu106-like could spread in different clones of E. coli and Klebsiella pneumoniae, revealing its underlying dissemination mechanism between Enterobacterales. Furthermore, the strain caused a decreased survival rate of larvae and produced high siderophore units (62.33%), similar to hypervirulent K. pneumoniae NTUH-K2044. CONCLUSIONS: The strains co-carrying the multidrug-resistant plasmid p2-Hu106 and virulent plasmid p1-Hu106 should be closely monitored to prevent its further spreading.

Facet sensitivity of iron carbides in Fischer-Tropsch synthesis.

Fischer-Tropsch synthesis (FTS) is a structure-sensitive reaction of which performance is strongly related to the active phase, particle size, and exposed facets. Compared with the full-pledged investigation on the active phase and particle size, the facet effect has been limited to theoretical studies or single-crystal surfaces, lacking experimental reports of practical catalysts, especially for Fe-based catalysts. Herein, we demonstrate the facet sensitivity of iron carbides in FTS. As the prerequisite, {202} and {112} facets of χ-Fe5C2 are fabricated as the outer shell through the conformal reconstruction of Fe3O4 nanocubes and octahedra, as the inner cores, respectively. During FTS, the activity and stability are highly sensitive to the exposed facet of iron carbides, whereas the facet sensitivity is not prominent for the chain growth. According to mechanistic studies, {202} χ-Fe5C2 surfaces follow hydrogen-assisted CO dissociation which lowers the activation energy compared with the direct CO dissociation over {112} surfaces, affording the high FTS activity.

Spatial decoupling of bromide-mediated process boosts propylene oxide electrosynthesis.

The electrochemical synthesis of propylene oxide is far from practical application due to the limited performance (including activity, stability, and selectivity). In this work, we spatially decouple the bromide-mediated process to avoid direct contact between the anode and propylene, where bromine is generated at the anode and then transferred into an independent reactor to react with propylene. This strategy effectively prevents the side reactions and eliminates the interference to stability caused by massive alkene input and vigorously stirred electrolytes. As expected, the selectivity for propylene oxide reaches above 99.9% with a remarkable Faradaic efficiency of 91% and stability of 750-h (>30 days). When the electrode area is scaled up to 25 cm2, 262 g of pure propylene oxide is obtained after 50-h continuous electrolysis at 6.25 A. These findings demonstrate that the electrochemical bromohydrin route represents a viable alternative for the manufacture of epoxides.

Efficient tandem electroreduction of nitrate into ammonia through coupling Cu single atoms with adjacent Co3O4.

The nitrate (NO3-) electroreduction into ammonia (NH3) represents a promising approach for sustainable NH3 synthesis. However, the variation of adsorption configurations renders great difficulties in the simultaneous optimization of binding energy for the intermediates. Though the extensively reported Cu-based electrocatalysts benefit NO3- adsorption, one of the key issues lies in the accumulation of nitrite (NO2-) due to its weak adsorption, resulting in the rapid deactivation of catalysts and sluggish kinetics of subsequent hydrogenation steps. Here we report a tandem electrocatalyst by combining Cu single atoms catalysts with adjacent Co3O4 nanosheets to boost the electroreduction of NO3- to NH3. The obtained tandem catalyst exhibits a yield rate for NH3 of 114.0 mg NH 3 h-1 cm-2, which exceeds the previous values for the reported Cu-based catalysts. Mechanism investigations unveil that the combination of Co3O4 regulates the adsorption configuration of NO2- and strengthens the binding with NO2-, thus accelerating the electroreduction of NO3- to NH3.