Search

Transition metal nitrogen carbon based single‐atom catalysts (SACs) have exhibited superior activity and selectivity for CO2 electroreduction to CO. A favorable local nitrogen coordination environment is key to construct efficient metal‐N moieties. Here, a facile plasma‐assisted and nitrogen vacancy (NV) induced coordinative reconstruction strategy is reported for this purpose. Under continuous plasma striking, the preformed pentagon pyrrolic N‐defects around Ni sites can be transformed to a stable pyridinic N dominant Ni‐N2 coordination structure with promoted kinetics toward the CO2‐to‐CO conversion. Both the CO selectivity and productivity increase markedly after the reconstruction, reaching a high CO Faradaic efficiency of 96% at mild overpotential of 590 mV and a large CO current density of 33 mA cm‐2 at 890 mV. X‐ray adsorption spectroscopy and density functional theory (DFT) calculations reveal this defective local N environment decreases the restraint on central Ni atoms and provides enough space to facilitate the adsorption and activation of CO2 molecule, leading to a reduced energy barrier for CO2 reduction. [ABSTRACT FROM AUTHOR]

A surface reconstructing phenomenon is discovered on a defect‐rich ultrathin Pd nanosheet catalyst for aqueous CO2 electroreduction. The pristine nanosheets with dominant (111) facet sites are transformed into crumpled sheet‐like structures prevalent in electrocatalytically active (100) sites. The reconstruction increases the density of active sites and reduces the CO binding strength on Pd surfaces, remarkably promoting the CO2 reduction to CO. A high CO Faradaic efficiency of 93 % is achieved with a site‐specific activity of 6.6 mA cm−2 at a moderate overpotential of 590 mV on the reconstructed 50 nm Pd nanosheets. Experimental and theoretical studies suggest the CO intermediate as a key factor driving the structural transformation during CO2 reduction. This study highlights the dynamic nature of defective metal nanosheets under reaction conditions and suggests new opportunities in surface engineering of 2D metal nanostructures to tune their electrocatalytic performance. [ABSTRACT FROM AUTHOR]

The utility of Cu(OTf)2 as the catalyst for the synthesis of a series of N - tert -butyl amides in excellent isolated yields via the reaction of nitriles (alkyl, aryl, benzyl, and furyl nitriles) with di- tert -butyl dicarbonate is described. Cu(OTf)2 is a highly stable and efficient catalyst for the present Ritter reaction under solvent-free conditions at room temperature. [ABSTRACT FROM AUTHOR]

The utility of Cu(OTf)2 as the catalyst for the synthesis of a series of N - tert -butyl amides in excellent isolated yields via the reaction of nitriles (alkyl, aryl, benzyl, and furyl nitriles) with di- tert -butyl dicarbonate is described. Cu(OTf)2 is a highly stable and efficient catalyst for the present Ritter reaction under solvent-free conditions at room temperature. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical carbon dioxide (CO2) reduction can produce valuable carbonaceous compounds that are in significant demand, due to its ability to decrease the accumulated atmospheric CO2 and improve the intermittent nature of renewable energy sources. Considering the sluggish kinetics of CO2 reduction reaction, the multielectron–proton transfer process, and the inevitable mixed reduction products, designing efficient and robust electrocatalysts that benefit from the structure–activity relationship is the focus to promote CO2 conversion. In this review, various metal‐based materials are first classified and discussed in terms of their structural and elemental compositions for catalytic behaviors. Afterward, the most intrinsic microstructural/electronic effects as well as the influence of compositional alteration on the catalyst activity, selectivity, and stability are summarized. Additionally, recent attempts to develop the assigned electrochemical cells are surveyed and described from a technological point of view. [ABSTRACT FROM AUTHOR]

Alloying Ni with Pd lowers the overpotential of benzaldehyde hydrogenation and obtains a reaction rate 20 times higher than that of Ni at 0.1 V vs. RHE, which is ascribed to the lower binding energy of benzaldehyde on the metal surface revealed by the in-situ IR study. [Display omitted] • Nanoporous nanowire NiPd alloys were synthesized using a dealloying method. • Alloying Ni and Pd lowers the overpotential of ECH of benzaldehyde. • The activity of NiPd alloy is comparable with Pd. • In-situ IR study reveals that Pd tunes the binding strength of adsorbed benzaldehyde. Ni is one of the most promising catalysts in aldehydes hydrogenation, although the high overpotential and low Faradaic efficiency limit its electrocatalytic performances. Here we introduce an effective and facile alloying strategy to tune the electronic structure of Ni. We demonstrate that alloying Pd to Ni can significantly boost the electrocatalytic performances of benzaldehyde hydrogenation and lower the overpotential to the level of pure Pd. Pd introduction enhances the electrocatalytic hydrogenation process over hydrogen evolution reaction (HER), and results in an increased Faradaic efficiency. The npnw-Ni 82 Pd 18 catalyst shows the optimal atomic ratio of Ni and Pd among the explored catalysts, and achieved a turnover frequency (TOF) value of 1387 mol mol metal -1h-1 at -0.1 V vs. reversible hydrogen electrode (RHE), higher than that of npnw-Ni (60 mol mol metal -1h-1) and comparable to np-Pd (1306 mol mol metal -1h-1) under the same reaction conditions. In-situ surface-enhanced infrared absorption spectroscopy study reveals that the electronic interactions between Ni and Pd would activate the adsorbed benzaldehyde, and therefore result in an enhanced activity in benzaldehyde hydrogenation. [ABSTRACT FROM AUTHOR]