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A unique electrochemical four-component reaction of terminal alkynes, (thio)xanthenes, nitriles, and water has been established in the absence of any catalyst or external oxidant. This electrochemical reaction features high atom economy and mild conditions, affording oxazole derivatives in moderate to good yields. [ABSTRACT FROM AUTHOR]

La0.8Sr0.2MnO3 (LSM) catalyst has been successfully prepared by solid phase method (G-LSM-T), sol–gel method (C-LSM-T) and molten salt method (S-LSM-T), using as-prepared MnCO3 microspheres as templates, respectively. It was shown that the S-LSM-550 catalyst presented well-formed perovskite structures, large specific surface area (49.65m2/g) and promising catalytic activity in CO oxidation, which T50 and T90 for CO conversion over fresh S-LSM-550 were 145.14 °C and 170.73 °C. The S-LSM-550 calcined at 550 °C for 2 h exhibited excellent thermal stability and catalytic activity compared with the samples prepared by solid phase method and sol–gel method. Its superior catalytic performance could be greatly attributed to its stable microstructure, high surface Mn4+/Mn3+ molar ratio and more available surface adsorbed oxygen species. [ABSTRACT FROM AUTHOR]

Development of hybrid catalysts with high activity, good stability and low cost is extremely desirable for hydrogen production by electrolysis of water. In this work, a hybrid composed of Ni 2 P nanoparticles (NPs) on N-doped reduced graphene oxide (NRGO) is synthesized via an in situ thermal decomposition approach for the first time and investigated as a catalyst for the hydrogen evolution reaction (HER). The as-synthesized Ni 2 P/NRGO hybrid exhibits an enhanced catalytic activity with low onset overpotential (37 mV), a small Tafel slope (59 mV dec −1 ), a much larger exchange current density (4.9 × 10 −5 A cm −2 ), and lower HER activation energy (46.9 kJ mol −1 ) than Ni 2 P/RGO hybrid. In addition, the Ni 2 P/NRGO hybrid maintains its catalytic activity for at least 60′000 s in acidic media. The enhanced catalytic activity is attributed to the synergistic effect of N-doped RGO and Ni 2 P NPs, the charged natures of Ni and P, as well as the high electrical conductivity of Ni 2 P/NRGO hybrid. This study may offer a new strategy for improving the electrocatalytic activity for hydrogen production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Perovskite-based catalyst was modified to improve catalytic activity. • Membrane filtration and catalytic oxidation was integrated effectively. • Abundant channel-assisted reaction sites were formed on membrane structure. • Refractory pollutants can be degraded by catalytic membrane in the presence of NOM. • Continuous outflow of feed stream guarantee favorable stability of membrane. Catalytic membrane that can simultaneously enable physical separation and advanced oxidation process is considered as a novel approach for wastewater remediation; however, the unsatisfied catalytic performance and instability impede its further application. In this study, Fe doped LaCoO 3 perovskite with tunable electron structure was employed as a heterogeneous catalyst and incorporated with Polyacrylonitrile ultrafiltration membrane via a controlled phase inversion method. Owing to the continuous outflow of the intermediates and enriched concentration gradients in membrane channels, the catalytic membrane exhibited exceptional catalytic performance and stability under cross-flow apparatus. Correspondingly, over 99% of tetracycline hydrochloride can be degraded via activating peroxymonosulfate in 36 min under the flux of 220 L/m2h. Besides, the catalytic membrane with suitable pore size could exclude natural organic matter and selectively assist the degradation of pollutants in membrane channels due to a massive generation of sulfate radicals and singlet oxygen (equivalent to a retention time of 1.64 s). Following this, the degradation pathways and toxicity analysis of the intermediates were investigated to further verify the catalysis mechanism and the reduced toxicity of treated solution. Overall, it can be concluded that the integration of membrane and catalytic oxidation is effective for enhancing wastewater purification efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ mineralization method was used to anchor β-FeOOH in confined membrane pores. • Highly dispersed nanocatalysts were constructed in membrane structure. • Confined pore structure increases the effective contact of radicals and pollutants. • High rejection and rapid pollutants degradation can be realized simultaneously. Heterogeneous advanced oxidation process performs a promising perspective in the field of refractory pollutant degradation. However, the agglomeration and difficulty-to-recycle characters of the heterogeneous catalysts greatly impede its further development. In this study, membrane-confined pores were employed as the immobilization support to anchor highly dispersed β-FeOOH via an in situ mineralization method, which not only exposed highly active sites for refractory pollutants degradation but also endowed the membrane with hydrophilic/underwater superoleophobic properties. Accordingly, the Polyvinylidene fluoride/β-FeOOH (PVDF/β-FeOOH) catalytic membrane demonstrated favorable separation capacity and attractive catalytic oxidation performance via activating peroxymonosulfate. Instantaneous degradation (contact time about 1 s) of recalcitrant pollutants (over 98%) and high oil rejections (96.4% to 99.1%) can be achieved simultaneously under low operating pressure. Both the confined pore structure-induced enhanced mass transfer and enrichment of radicals and pollutants lead to favorable catalytic degradation performance. The mechanism of the catalytic membrane was analyzed by radical quenching test and electron paramagnetic resonance analysis, proving that sulfate radicals were predominant reactive oxygen species during catalytic oxidation. Besides, the PVDF/β-FeOOH catalytic membrane also possessed attractive stability without tedious catalyst separation/recovery processes. This work provides a meaningful tactic to further enhance the catalytic oxidation performance of catalytic membrane in water treatment. [ABSTRACT FROM AUTHOR]

The development of methods for selective cleavage reactions of thermodynamically stable C−C/C=C bonds in a green manner is a challenging research field which is largely unexplored. Herein, we present a heterogeneous Fe−N−C catalyst with highly dispersed iron centers that allows for the oxidative C−C/C=C bond cleavage of amines, secondary alcohols, ketones, and olefins in the presence of air (O2) and water (H2O). Mechanistic studies reveal the presence of water to be essential for the performance of the Fe−N−C system, boosting the product yield from <1 % to >90 %. Combined spectroscopic characterizations and control experiments suggest the singlet 1O2 and hydroxide species generated from O2 and H2O, respectively, take selectively part in the C−C bond cleavage. The broad applicability (>40 examples) even for complex drugs as well as high activity, selectivity, and durability under comparably mild conditions highlight this unique catalytic system. [ABSTRACT FROM AUTHOR]

The development of methods for selective cleavage reactions of thermodynamically stable C−C/C=C bonds in a green manner is a challenging research field which is largely unexplored. Herein, we present a heterogeneous Fe−N−C catalyst with highly dispersed iron centers that allows for the oxidative C−C/C=C bond cleavage of amines, secondary alcohols, ketones, and olefins in the presence of air (O2) and water (H2O). Mechanistic studies reveal the presence of water to be essential for the performance of the Fe−N−C system, boosting the product yield from <1 % to >90 %. Combined spectroscopic characterizations and control experiments suggest the singlet 1O2 and hydroxide species generated from O2 and H2O, respectively, take selectively part in the C−C bond cleavage. The broad applicability (>40 examples) even for complex drugs as well as high activity, selectivity, and durability under comparably mild conditions highlight this unique catalytic system. [ABSTRACT FROM AUTHOR]

Fundamental understanding of the synergistic effect of bimetallic catalysts is of extreme significance in heterogeneous catalysis, but a great challenge lies in the precise construction of uniform dual‐metal sites. Here, we develop a novel method for constructing Pt1−Fe1/ND dual‐single‐atom catalyst, by anchoring Pt single atoms on Fe1−N4 sites decorating a nanodiamond (ND) surface. Using this catalyst, the synergy of nitroarenes selective hydrogenation is revealed. In detail, hydrogen is activated on the Pt1−Fe1 dual site and the nitro group is strongly adsorbed on the Fe1 site via a vertical configuration for subsequent hydrogenation. Such synergistic effect decreases the activation energy and results in an unprecedented catalytic performance (3.1 s−1 turnover frequency, ca. 100 % selectivity, 24 types of substrates). Our findings advance the applications of dual‐single‐atom catalysts in selective hydrogenations and open up a new way to explore the nature of synergistic catalysis at the atomic level. [ABSTRACT FROM AUTHOR]

Fundamental understanding of the synergistic effect of bimetallic catalysts is of extreme significance in heterogeneous catalysis, but a great challenge lies in the precise construction of uniform dual‐metal sites. Here, we develop a novel method for constructing Pt1−Fe1/ND dual‐single‐atom catalyst, by anchoring Pt single atoms on Fe1−N4 sites decorating a nanodiamond (ND) surface. Using this catalyst, the synergy of nitroarenes selective hydrogenation is revealed. In detail, hydrogen is activated on the Pt1−Fe1 dual site and the nitro group is strongly adsorbed on the Fe1 site via a vertical configuration for subsequent hydrogenation. Such synergistic effect decreases the activation energy and results in an unprecedented catalytic performance (3.1 s−1 turnover frequency, ca. 100 % selectivity, 24 types of substrates). Our findings advance the applications of dual‐single‐atom catalysts in selective hydrogenations and open up a new way to explore the nature of synergistic catalysis at the atomic level. [ABSTRACT FROM AUTHOR]

Atomically dispersed Zn–N–C nanomaterials are promising platinum‐free catalysts for the oxygen reduction reaction (ORR). However, the fabrication of Zn–N–C catalysts with a high Zn loading remains a formidable challenge owing to the high volatility of the Zn precursor during high‐temperature annealing. Herein, we report that an atomically dispersed Zn–N–C catalyst with an ultrahigh Zn loading of 9.33 wt % could be successfully prepared by simply adopting a very low annealing rate of 1° min−1. The Zn–N–C catalyst exhibited comparable ORR activity to that of Fe–N–C catalysts, and significantly better ORR stability than Fe–N–C catalysts in both acidic and alkaline media. Further experiments and DFT calculations demonstrated that the Zn–N–C catalyst was less susceptible to protonation than the corresponding Fe–N–C catalyst in an acidic medium. DFT calculations revealed that the Zn–N4 structure is more electrochemically stable than the Fe–N4 structure during the ORR process. [ABSTRACT FROM AUTHOR]

Ammonium carbonate-assisted mechanochemical preparation of Cu-based catalysts has been developed for steam reforming of methanol (SRM). The characteristics of the catalysts were studied by N2 adsorption–desorption, N2O titration, TEM, XRD, XPS, H2-TPR, and TG analysis. Optimized-prepared samples showed a porous structure with high surface areas due to the ammonium carbonate decomposing during the calcination. Because of the positive correlation between surface area and catalytic activity, the porous catalysts exhibited superior SRM activity, e.g., Cu1Zn1Zr1Al7 with a high surface area of 147.1 m2 g−1 reached a maximum methanol conversion of 85.2%. Furthermore, more Cu–Al spinels were introduced on Cu1Zn1Al8 by the milling process compared to wet-impregnated IM-Cu1Zn1Al8. Ascribed to the interaction of dispersed copper components with the surface oxygen vacancies of the CeO2/ZrO2, the promoted reducibility was observed with reduction peaks observed at low temperatures of 170 and 152 °C. With CexZr1−xO2 solid solution in Cu1Zn1Ce1Zr1Al6, a high surface-oxygen population was clearly formed on the surface, which suppressed CO production (0.8%) in the reaction. The ball-milled catalysts were found to have a much better catalytic time-on-stream stability, while the degradation of IM-Cu1Zn1Al8 was mainly ascribed to Cu sintering in the reaction, not the carbon deposits. [ABSTRACT FROM AUTHOR]

[Display omitted] • An extension of classic deep oxidation CuMnOx catalysts to selective oxidation of alcohol with high efficiency. • CuMnOx catalysts characterized by Mn 2 O 3 -Cu 1.4 Mn 1.6 O 4 and CuO-Cu 1.4 Mn 1.6 O 4 oxide pairs. • Mn 2 O 3 -Cu 1.4 Mn 1.6 O 4 oxide pair is more active than CuO-Cu 1.4 Mn 1.6 O 4 oxide pair. • Rich Cu+ species in Mn 2 O 3 -Cu 1.4 Mn 1.6 O 4 oxide pair is essential to achieve high catalytic activity. This work presents an extension of classic deep oxidation CuMnOx catalysts to a selective oxidation of alcohol with high efficiency and in an environmental-friendly reaction system. A series of CuMnOx catalysts characterized by CuO-Cu 1.4 Mn 1.6 O 4 and Mn 2 O 3 -Cu 1.4 Mn 1.6 O 4 oxide pairs were prepared via a novel half carbonized citrus grandis peel assisted hard template method. A shift of the oxide pairs from CuO-Cu 1.4 Mn 1.6 O 4 to Mn 2 O 3 -Cu 1.4 Mn 1.6 O 4 has been achieved by tuning Cu/Mn molar ratio, and then leads to a one-pass benzaldehyde yield more than 50% with 100% benzaldehyde selectivity in the selective oxidation of benzyl alcohol using H 2 O 2 as oxidant. Higher relative amount of Cu 1.4 Mn 1.6 O 4 in either Mn 2 O 3 -Cu 1.4 Mn 1.6 O 4 or CuO-Cu 1.4 Mn 1.6 O 4 oxide pair is found to be essential for achieving high catalytic activity. The interaction between the Cu 1.4 Mn 1.6 O 4 constituent and Mn 2 O 3 constituent of Mn 2 O 3 -Cu 1.4 Mn 1.6 O 4 oxide pair is found to able to enhance the formation of Cu+ species, which can reacts with H 2 O 2 to produce •OH and then touch off a Fenton-like catalytic oxidation process of benzyl alcohol, in the current CuMnOx-H 2 O 2 system, to produce benzaldehyde with high selectivity. This work presents a new perspective in the development of highly effective and low cost CuMnOx catalysts for heterogeneous catalytic oxidation reactions. [ABSTRACT FROM AUTHOR]

Dual-atomic-site catalysts (DASCs), as an extension of single-atom catalysts (SACs), have attracted increasing attention owing to the synergistic effect. However, the study of DASCs is still at the early stages and mainly based on metal atom pairs. More experimental and theoretical exploration needed for further guiding the reasonable design of diatomic active sites. Herein, remarkable activity for oxygen reduction reaction (ORR) of Se 1 -NC single-atom catalyst was discovered, and then Fe/Se dual-atom catalysts were constructed to demonstrate the dual-atom sites synergistic effect. Encouraging, the Fe 1 Se 1 -NC catalyst displays significant enhancement for ORR towards Fe 1 -NC and Se 1 -NC in both alkaline and acid electrolytes. Spectroscopic characterizations and theoretical calculations reveal that there are multiple effects for the introduction of Se, especially for supplying new active sites, and effectively tuning charge redistribution and the spin-state of Fe active sites, which presenting a new strategy to improve the electrochemical performance based on the metal-nonmetal dual-atomic-site catalysts. Atomically dispersed metal(Fe) and non-metal (Se) dual atoms anchored on nitrogen-doped carbon for the first time. The co-exist of Fe-N 5 moiety and SeC 2 dual active sites displays significant synergetic enhancement for ORR towards Fe 1 -NC and Se 1 -NC. This work provides a unique insights of atomical introducing of non-metal active sites for rational design of more effective catalysts. [Display omitted] • Metal(Fe) and nonmetal(Se) dual-atom sites are prepared for the first time, which displays significant enhancement for ORR. • DFT calculations indicate that the co-exist of Fe and Se dual-atomic-site is more beneficial to *OH desorption process. • Se atom has several functions: (1) adjust the electronic state of the Fe-N X. (2) Serve as ORR site. (3) Create rich pores. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new understanding in the active site of CuMnOx catalysts. • CuMnOx catalysts are composed by uniform CuO-Mn 2 O 3 oxide pairs. • Highly isolated CuO nano-particles are essential for CuO-Mn 2 O 3 oxide pairs. • Cu-O-Mn sites are found to be the active sites of CuO-Mn 2 O 3 oxide pairs. The current work provide a new understanding on the active site of CuMnOx catalysts and thus offer a new perspective in the development of highly effective and low cost CuMnOx catalysts for heterogeneous catalytic oxidation reactions. A series of dual-component copper-manganese multi-oxide catalysts (CuMnOx) have been successfully synthesized using a surfactant assisted hydrolysis-hydrothermal method and studied by XRD, N 2 adsorption–desorption test, ICP-AES, SEM, Aberration-corrected HADDF-STEM, HRTEM, FT-IR, Raman, XPS, H 2 -TPR. These CuMnOx catalysts were found to be composed with uniform CuO-Mn 2 O 3 oxide pair structure, in which highly isolated/dispersed CuO species are anchored in the framework of Mn 2 O 3. It was found that the speciation in these CuMnOx catalysts presents a shift from highly isolated or even single Cu2+ oxide species (Cu2+Ox) to CuO nanoclusters and CuO microcrystalline with increasing Cu content. In CO oxidation reaction, which was employed to probe the structure of the CuO-Mn 2 O 3 oxide pairs in these CuMnOx catalysts, the Cu-O-Mn sites in those CuMnOx catalysts with highly isolated or highly dispersed CuO species were found to be highly active. For CuO-Mn 2 O 3 oxide pair catalysts, the highly isolated/dispersed CuO species in Mn 2 O 3 framework is essential to achieve high activity. [ABSTRACT FROM AUTHOR]

Spent hydrodesulfurization (HDS) catalysts, containing considerable amount of pollutants and metals including vanadium (V), molybdenum (Mo), aluminum (Al), and nickel (Ni), are considered as hazardous wastes which will result in not only ecosystem damage but also squandering resource. Herein, a process featuring blank roasting-alkaline leaching is proposed to recover spent HDS catalyst. During roasting, low-valence compounds convert to high-valence oxides which can be leached out by NaOH solution. Afterwards, leaching solution is subjected to crystallization to separate metals. The results show that for samples roasted at 650 °C, 97% V, 96% Mo, and 88% Al are leached out at optimal condition; for samples roasted at 1000 °C, selective leaching of 91% V and 96% Mo respectively, are realized, with negligible Al being dissolved. NiO is insoluble in strong alkali leaving in residue. The advantages of this process are that first, the leaching of V, Mo, and Al can be manipulated by controlling roasting conditions, providing flexible process design. Second, leaching solution can be fully recycled. Finally, mild leaching condition and clean separation of V, Mo, and Al is achieved, proving fundamental information for peer researches to facilitate their future research on the development of more efficient and cleaner technologies. [Display omitted] • Blank roasting-alkaline leaching process is proposed. • Phases transformation of Al 2 O 3 , MoS 2 and V 2 S 3 during roasting are discussed. • Roasting at 650 °C results in co-leaching of V, Mo, and Al. • Roasting at 1000 °C enables a selective leaching of V and Mo without Al. [ABSTRACT FROM AUTHOR]