Search

Plasma catalysis has recently been recognized as a promising route for artificial N2 reduction under mild conditions. Here we report a highly active VN catalyst for plasma-catalytic NH3 synthesis via the typical Mars–van Krevelen (MvK) mechanism. Our results indicate that NH3 synthesis occurs through the continuous regeneration and elimination of nitrogen vacancies on the VN surface. With this strategy, the VN catalyst achieves a superhigh NH3 yield of 143.2 mg h−1 gcat.−1 and a competitive energy efficiency of 1.43 gNH3 kW h−1. [ABSTRACT FROM AUTHOR]

Minimizing noble-metal (NM) usage by exposing all metal atoms on surfaces for catalysis has been a longstanding goal in the development of highly efficient NM catalysts. Here, we realized the full utilization of Pt and Ru atoms by anchoring the cross-linked PtRu multi-atom on the surface of atomically dispersed Zn, Fe and N tri-doped carbon nanomaterials through Pt–N and Ru–N bonds. This supported bimetallic PtRu multi-atom catalyst has extremely high atom efficiency and shows excellent stability and high activity towards the methanol oxidation reaction (MOR). Density functional theory (DFT) calculations reveal that the strongly coupled Pt–N and Ru–N bonds are critical for stabilizing multi-atom PtRu. [ABSTRACT FROM AUTHOR]

• We succeeded in fabricating a surface Ru enriched structurally ordered intermetallic PtFe@PtRuFe nanostructure. • We found that the atomic radius of Fe and Ru is a highly decisive factor for the surface composition of the PtFe@PtRuFe. • The well-Constructed PtFe@PtRuFe catalyst exhibits excellent anti-CO poisoning ability and MOR catalytic activity. Atomic-level control of the surface composition and atomic arrangement of multimetalic alloy nanocatalyst has emerged as an effective strategy to optimize their catalytic performance. By integrating the space-confined alloying and surface engineering strategies, we demonstrate a new class of core-shell structured PtFe@PtRuFe nanocatalyst, composed of an ordered PtFe intermetallic core with a 3–5 atomic-layers-thick PtRuFe shell. The well-defined PtFe@PtRuFe core-shell nanostructure exhibits excellent anti-CO poisoning ability and resistance to Fe leaching, achieving a factor of 1.68 enhancement in mass activity and a factor of 1.57 improvement in specific activity toward methanol oxidation reaction (MOR) compared to the state-of-the-art PtRu/C catalysts. Furthermore, the CO anodic oxidation on the PtFe@PtRuFe catalyst surface (0.39 V) starts much earlier than on the commercial PtRu/C (0.43 V) and Pt/C (0.83 V) catalysts. The enhanced MOR activity and anti-CO poisoning ability of the PtFe@PtRuFe catalyst is mainly attributed to the well-defined core-shell structure and favorable composition as well as the charge transfer from Fe/Ru to Pt and thusly be weakened Pt-CO ads adsorption energy. This novel core-shell structured nanocatalyst provide a new direction to reduce the usage of noble metal, tune the surface composition and atomic arrangement, enhance the activity and stability of multimetalic alloy nanocatalyst. [ABSTRACT FROM AUTHOR]

Forced obedience: Layer‐structured montmorillonite (MMT) was used as a nanoreactor for the generation of planar pyridinic and pyrrolic N sites in nitrogen‐doped graphene (NG; see picture). The selectivity for the formation of planar N sites was inversely proportional to the interspace width (δ) of the MMT and reached a maximum of 90.27 %. The NG catalyst exhibited low electrical resistance, high electrocatalytic activity, and good stability. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic activity of β-MnO2 with high-index (211) and (2-2-1) surfaces for oxygen reduction (ORR) were studied using density functional theory (DFT). MnO2 (2-2-1) has a higher HOMO energy level and a higher electric conductivity than MnO2 (211). Thus, MnO2 (2-2-1) surface is more beneficial for electron transfer between the O2 and the catalyst. The calculation of the adsorption energies shows that the MnO2 (211) surface has a stronger interaction with the intermediate OH of the ORR than the MnO2 (2-2-1) surface. Therefore, the activity of MnO2 (211) is inferior to that of MnO2 (2-2-1) for ORR catalysis. [Copyright &y& Elsevier]

• Cross-linked multi-atom Pt anchored on a Zn, Fe and N co-doped carbon catalyst is prepared. • The MAC-Pt/ZnFe -N- C catalyst shows 100 % exposure of surface Pt atoms. • The MAC-Pt/ZnFe -N- C catalyst exhibits remarkable catalytic activity and stability for the oxygen reduction reaction. • A fuel cell assembled by this catalyst delivers a maximal power output of 1.02 W cm−2 at 0.035 mg Pt cm−2 at the cathode. Although single-atom catalysts (SACs) are drawing wide attention because they offer properties that differ from those of conventional nanoparticle (NP)-based catalysts, the lack of neighboring metal centers to cooperate in catalysis limits their actual application in many important chemical processes. Here, we report the synthesis of multi-atom Pt catalyst that consists of cross-linked Pt-Pt metal centers stabilized by atomically dispersed ZnFe -N- C support through Pt-N bonds. XAFS analysis reveals that each Pt atom in the multi-atom Pt catalyst coordinates with ∼2.6 N atoms and ∼4.3 Pt atoms. This novel catalyst combines the merits of SACs and NPs, resulting in 100 % exposure of surface Pt atoms and excellent stability and fuel cell performance. With an ultralow Pt loading of 0.035 mg cm−2 at the cathode, the fuel cell delivers a 1.02 W cm-2 maximal power output. DFT calculations revealed that the strongly coupled Pt-N bond is critical for stabilizing the cross-linked Pt. [ABSTRACT FROM AUTHOR]