Atomically dispersed Ni as the active site towards selective hydrogenation of nitroarenes

Abstract

Rational design of heterogeneous non-noble metal catalysts as highly efficient and selective catalysts for hydrogenation of nitroarenes with hydrogen as the reducing agent is currently a great challenge, which has attracted a great deal of attention. Herein, a new strategy for achieving atomic dispersion of Ni atoms on nitrogen-doped porous carbon (Ni–N–C) with a specific surface area of up to 810 m² g⁻¹ and nickel loading as high as 4.4 wt% is developed, yielding high activity, chemoselectivity, and reusability of catalysts in the hydrogenation of nitroarenes using hydrogen as the reductant with a turnover of number (TON) value of 84 and a turnover of frequency (TOF) value of 8.4 h⁻¹ for the first time. The Ni single atoms anchored on N-doped porous carbon by binding with nitrogen/carbon have been proved to be the active sites. Importantly, the Ni–N₃ active species is found to contribute more activity compared with Ni–N₂ and Ni–N₄. Density functional theory (DFT) calculations also reveal that the Ni–N₃ structure exhibits the highest activity according to the lowest adsorption energy and the longest elongation N–O bonds of nitrobenzene, which originated from the induced charge transfer. This work opens a new route for rational design and accurate modulation of nanostructured organic molecular transformation catalysts at the atomic scale.