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Construction of isolated Ni sites on nitrogen-doped hollow carbon spheres with Ni–N3 configuration for enhanced reduction of nitroarenes
Nano Research 2022, 15 (7): 6001-6009
Published: 04 May 2022
Downloads:55

Designing and synthesizing high-efficiency non-precious metal-based catalysts having uniform active sites increases the reactivity and selectivity of materials and provides a platform for an in-depth understanding of their catalytic reaction mechanism. In this study, we provided an approach for fabricating isolated nickel single-atom sites (Ni SAs) with high loading (4.9 wt.%) stabilized on nitrogen-doped hollow carbon spheres (NHCS) using a core–shell structured Zn/Ni bimetallic zeolitic imidazolate framework (ZIF) composite as the sacrificial template. The as-fabricated Ni SAs/NHCS catalyst shows superior activity, selectivity, and recycling durability for the catalytic transfer hydrogenation of nitrobenzene to aniline, thus achieving 100% yield of aniline with a turn-over frequency (TOF) value as high as 29.9 h−1 under mild conditions. This TOF value is considerably superior to the supported Ni nanoparticle catalysts. The experiments designed show that the hollow structure feature of NHCS facilitates accessible active sites and mass transfer, which thus contributes to the enhancement of the catalytic performance of Ni SAs/NHCS. Density functional theory calculations show the high chemo-selectivity and activity of the Ni SAs catalyst, arising from the unique role of the single Ni-N3 site on simultaneously activating the H donor (N2H4) and substrate, as well as the hydrogenation of the –NOH group as the rate-determining step.

Research Article Issue
Porous β-FeOOH nanotube stabilizing Au single atom for high-efficiency nitrogen fixation
Nano Research 2022, 15 (4): 3026-3033
Published: 18 November 2021
Downloads:31

Electrochemical nitrogen reduction reaction (NRR) under ambient conditions is highly desirable to achieve sustainable ammonia (NH3) production via an alternative carbon free strategy. Single-atom catalysts (SACs) with super high atomic utilization and catalytic efficiency exhibit great potential for NRR. Herein, a high-performance NRR SAC is facilely prepared via a simple deposition method to anchor Au single atoms onto porous β-FeOOH nanotubes. The resulting Au-SA/FeOOH can efficiently drive NRR under ambient conditions, and the NH3 yield reaches as high as 2,860 μg·h−1·mgAu−1 at −0.4 V vs. reversible hydrogen electrode (RHE) with 14.2% faradaic efficiency, much superior to those of all the reported Au-based electrocatalysts. Systematic investigations demonstrate that the synergy of much enhanced N2 adsorption, directional electron export, and mass transfer ability in Au-SA/FeOOH greatly contributes to the superior NRR activity. This work highlights a new insight into the design of high efficient NRR electrocatalysts by combination of porous metal oxide matrix and highly active single-atom sites.

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