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Electrocatalytic water splitting that is coupled with electrocatalytic chemical oxidation is considered as one of the promising methods for efficiently obtaining hydrogen energy and fine chemicals. Herein, we focus on an electrochemical redox activation strategy to rationally manipulate the microstructure and surface valence states of copper foam (CF) and boost the corresponding performance towards electrocatalytic benzyl alcohol oxidation (EBA), accompanied by the efficient hydrogen production. Correspondingly, the Cu(II)‐dominated species are gradually formed on the CF surface with the dissolution and redeposition of copper in the suitable potential range. The new species containing Cu2O, CuO, and Cu(OH)2 during surface reconstruction process of the CF were confirmed by multiple characterization techniques. After 220‐cycled activation (CF‐220), the activated CF achieves an increase of current density for EBA in anode from 9.5 for the original CF to 29.3 mmol/cm2, while the pure hydrogen yield increases threefold than that of the original CF at 1.5 VRHE. The produced new species can endow the CF‐220 with abundant acidity sites, which can enhance the adsorption toward Lewis‐basicity benzyl alcohol, confirmed by NH3‐temperature‐programmed desorption. In situ Raman result further reveals that the as‐produced CuO, Cu(OH)2, and Cu(OH)42− are the main active species toward the EBA process. [ABSTRACT FROM AUTHOR]

Electrocatalytic synthesis of aldehydes from alcohols exhibits unique superiorities as a promising technology, in which cascade reactions are involved. However, the cascade reactions are severely limited by the low selectivity resulting from the peroxidation of aldehydes in a traditional liquid‐solid system. Herein, we report a novel liquid‐liquid‐solid system to regulate the selectivity of benzyl alcohol electrooxidation. The selectivity of benzaldehyde increases 200‐fold from 0.4 % to 80.4 % compared with the liquid‐solid system at a high current density of 136 mA cm−2, which is the highest one up to date. In the tri‐phase system, the benzaldehyde peroxidation is suppressed efficiently, with the conversion of benzaldehyde being decreased from 87.6 % to 3.8 %. The as‐produced benzaldehyde can be in situ extracted to toluene phase and separated from the electrolyte to get purified benzaldehyde. This strategy provides an efficient way to efficiently enhance the selectivity of electrocatalytic cascade reactions. [ABSTRACT FROM AUTHOR]

The electrocatalytic N2 reduction reaction (NRR) to ammonia (NH3) driven by intermittent renewable electricity under ambient conditions offers an alternative to the energy-intensive Haber–Bosch process. However, as a distinct core of the process, the design strategy of the electrocatalyst for enhancing the N2 activation ability is still in a trial-and-error stage due to the absence of theoretical guidance. As a result, the corresponding NH3 yield rate and selectivity are much lower than that required for implementation at scale. In this work, on the basis of the hard–soft acid–base theory, we report a paradigm for the design of an electrocatalyst with tuned Lewis acidity to efficiently activate and reduce N2 to NH3. As a proof of concept, it is revealed that enhancing the Lewis acidity of the molybdenum sulfide (MoSx) model catalyst supported on carbon nanotubes can greatly improve its activation ability toward the N2 molecule. Accordingly, a high faradaic efficiency of 21.60 ± 2.35% and NH3 yield rate of 40.4 ± 3.6 μg h−1 mgcat.−1 are obtained over the modified MoSx, which are ∼2 times enhanced in comparison with the original MoSx, respectively. Density functional theory calculations verify that the electron transfer from the occupied σ orbitals of N2 to the empty d orbitals of Mo sites within MoSx can be greatly accelerated by tuning the Lewis acidity of MoSx to match with the basicity of N2, thereby enhancing the N2 activation process via the σ → d donation mechanism. [ABSTRACT FROM AUTHOR]

Integrated/cascade plasma-enabled N 2 oxidation and electrocatalytic NO x - (where x = 2, 3) reduction reaction (pNOR-eNO x - RR) holds great promise for the renewable synthesis of ammonia (NH 3 ). However, the corresponding activated effects and process of plasma toward N 2 and O 2 molecules and the mechanism of eNO x - RR to NH 3 are unclear and need to be further uncovered, which largely limits the large-scale deployment of this process integration technology. Herein, we systematically investigate the plasma-enabled activation and recombination processes of N 2 and O 2 molecules, and more meaningfully, the mechanism of eNO x - RR at a microscopic level is also decoupled using copper (Cu) nanoparticles as a representative electrocatalyst. The concentration of produced NO x in the pNOR system is confirmed as a function of the length for spark discharge as well as the volumetric ratio for N 2 and O 2 feeding gas. The successive protonation process of NO x - and the key N-containing intermediates (e.g., -NH 2 ) of eNO x - RR are detected with in situ infrared spectroscopy. Besides, in situ Raman spectroscopy further reveals the dynamic reconstruction process of Cu nanoparticles during the eNO x - RR process. The Cu nanoparticle-driven pNOR-eNO x - RR system can finally achieve a high NH 3 yield rate of ∼40 nmol s -1 cm -2 and Faradaic efficiency of nearly 90%, overperforming the benchmarks reported in the literature. It is anticipated that this work will stimulate the practical development of the pNOR-eNO x - RR system for the green electrosynthesis of NH 3 directly from air and water under ambient conditions.

The Pd/C catalysts are widely used in synthesis of fine chemicals in industry, but their production suffers from a complicated two-step process involving impregnation and reduction, and requires large amounts of solvents and reductant, which would lead to a series of issues such as time consumption, resource waste and environmental pollution. Herein, ultra-small Pd nanoparticles uniformly anchored on carbon nanotubes (Pd/CNTs) were synthesized by using a one-pot and low-temperature reduction strategy. The present process/technology is very sensitive to and controlled by the supports and solvents, and the carbon support and acetic acid synergistically play crucial and decisive roles in the fast production of Pd/C catalysts. Also, the used solvents can be recycled and reutilized, which meets the requirements of sustainable chemistry and green economy. When the as-obtained Pd/CNTs catalyst was used to catalyze the oxidation of benzyl alcohol to benzaldehyde, it achieved a conversion efficiency as high as 99.3 % and a high selectivity up to >99.9 %. The simple, scalable and environmentally friendly strategy can be extended to anchor Pd nanoparticles on various carbon substrates, which sheds a new light on the synthesis of Pd/C catalysts., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A wide range of 2-substituted benzoxazoles can be efficiently synthesized from N-(2-iodo-/bromo-phenyl)benzamides, and even the less reactive N-(2-chlorophenyl)benzamides, via Cu-catalysed intramolecular coupling cyclization reactions using methyl 2-methoxybenzoate as the ligand under mild reaction conditions. In addition, the benzoxazoles can be easily prepared from the primary amides coupling with o-dihalobenzenes in a single step.