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Decoration of Pd Nanoparticles with N and S Doped Carbon Quantum Dots as a Robust Catalyst for the Chemoselective Hydrogenation Reaction

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journal contribution
posted on 17.04.2019, 00:00 by Chunshan Lu, Qianwen Zhu, Xuejie Zhang, Haoke Ji, Yebin Zhou, Hao Wang, Qiangqiang Liu, Juanjuan Nie, Wenfeng Han, Xiaonian Li
Achieving high selectivity is one of the major challenges for the noble metal catalysts. A strategy of decoration of Pd nanoparticles by N–S doped carbon quantum dots (N,S-CQDs) to regulate selectivity is proposed. Through adjusting the loading amounts of N,S-CQDs, high selectivity toward catalytic hydrogenation reactions can be obtained. N,S-CQDs facilely adhere to the Pd nanoparticle via surface reactions among C–S/C–N species of N,S-CQDs and C–O species of the carbon support under the catalysis of Pd particles. N loss was detected due to the transformation of some C–N species into nitrogen-containing soluble substances or gas. However, S-containing species, specially −SO2/SO3 species, are turned into C–S–C (thiophene-S), leading to a strong coordination between Pd and S. As a result, a N,S-CQDs-Pd interface is fabricated, in which electrons transfer from Pd to S species and the interface of Pd–S plays a major role in hydrogen spillover and generation of dissociated hydrogen with negative charge. Consequently, Pd@N,S-CQDs suppress the hydrode­halogenation and exhibit superior conversion and selectivity (both 100%) for the selective hydrogenation of various halonitrobenzenes. N,S-CQDs as a nonmetallic promoter of metal catalysts provides a promising strategy for the improvement of selectivity.