Selective photocatalytic semihydrogenation of alkynols to alkenols on Pd-C3N4 nanosheets under ambient conditions

Zhipeng Ren; Lei Zhang; Jinjin Li; Jun Bu; Wenxiu Ma; Zhihao Zhao; Zhenpeng Liu; Jian Zhang

doi:10.1016/j.jcis.2023.09.062

Selective photocatalytic semihydrogenation of alkynols to alkenols on Pd-C₃N₄ nanosheets under ambient conditions

J Colloid Interface Sci. 2024 Jan;653(Pt A):39-45. doi: 10.1016/j.jcis.2023.09.062. Epub 2023 Sep 9.

Authors

Zhipeng Ren¹, Lei Zhang², Jinjin Li², Jun Bu², Wenxiu Ma², Zhihao Zhao³, Zhenpeng Liu⁴, Jian Zhang⁵

Affiliations

¹ Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology and Department of Advanced Chemical Engineering, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an 710129, PR China; State Key Laboratory of Solidification Processing and School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China.
² Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology and Department of Advanced Chemical Engineering, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an 710129, PR China.
³ State Key Laboratory of Solidification Processing and School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China.
⁴ State Key Laboratory of Solidification Processing and School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China. Electronic address: liuzp@nwpu.edu.cn.
⁵ Key Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology and Department of Advanced Chemical Engineering, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an 710129, PR China; State Key Laboratory of Solidification Processing and School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China. Electronic address: zhangjian@nwpu.edu.cn.

PMID: 37708730
DOI: 10.1016/j.jcis.2023.09.062

Abstract

Selective hydrogenation of alkynols to alkenols is an essential process for producing fine and intermediate chemicals. Currently, thermocatalytic alkynol hydrogenation faces several challenges, e.g., the safety of high-pressure hydrogen (H₂) gas and the need for elevated temperature, and unavoidable side reactions, e.g., overhydrogenation. Here, a novel photocatalytic strategy is proposed for selectively reducing alkynols to alkenols with water as a hydrogen source under ambient temperature and pressure. Under the irradiation of simulated solar light, carbon nitride (C₃N₄) nanosheets with palladium (Pd) nanoparticles as cocatalysts (Pd-C₃N₄ NSs) exhibit a 2-methyl-3-butyn-2-ol (MBY) conversion of 98% and 2-methyl-3-buten-2-ol (MBE) selectivity of 95%, outperforming state-of-the-art thermocatalysts and electrocatalysts. After natural-sunlight irradiation (average light intensity of 25.13 mW cm^-2) for 36 h, a MBY conversion of 98% and MBE selectivity of 92% was achieved in a large-scale photocatalytic system (2500 cm²). Experimental and theoretical investigations reveal that Pd cocatalysts on C₃N₄ facilitate the adsorption and hydrogenation of MBY as well as the formation of active hydrogen species, which promote the selective semihydrogenation of alkynols. Moreover, the proposed strategy is applicable to various water-soluble alkynols. This work paves the way for photocatalytic strategies to replace thermocatalytic hydrogenation processes using pressurized hydrogen.

Keywords: Alkenol; Alkynol; DFT calculations; Photocatalysts; Selective hydrogenation.