Chinese Journal of Catalysis ›› 2023, Vol. 54: 188-198.DOI: 10.1016/S1872-2067(23)64523-1

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Metalated carbon nitride with facilitated electron transfer pathway for selective NADH regeneration and photoenzyme-coupled CO2 reduction

Pengye Zhanga,1, Wenjin Donga,1, Yuanyuan Zhanga, Li-Nan Zhaoa,b, Hualei Yuana, Chuanjun Wanga, Wenshuo Wanga, Hanxiao Wanga, Hongyu Zhanga, Jian Liua,b,*()   

  1. aQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Shandong Energy Institute, Qingdao New Energy Shandong Laboratory, Qingdao 266101, Shandong, China
    bCollege of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, Shandong, China
  • Received:2023-07-31 Accepted:2023-09-28 Online:2023-11-18 Published:2023-11-15
  • Contact: *E-mail: liujian@qibebt.ac.cn (J. Liu).
  • About author:1Contributed equally to this work.
  • Supported by:
    National Natural Science Foundation of China(22175104);Natural Science Foundation of Shandong Province(ZR2019ZD47);Taishan Scholars Program

Abstract:

Photoenzyme-coupled catalysis, featuring the integration of photocatalysis with enzymes, is very promising for next-generation green biomanufacturing. The presence of an Rh complex is a prerequisite for the efficient photocatalytic regeneration of the reduced form of nicotinamide adenine dinucleotide (NADH), which poses the issue of immobilizing homogeneous complexes. In this study, a novel immobilization method based on the thermal polymerization of 2,2'-bipyridine-5,5'-diamine (DABP) onto a polymeric carbon nitride (PCN) framework is proposed. PCNbpy4 is metalated by immobilizing Rh on the terminal bipyridine structure. Notably, partial DABP has the ability to undergo high-temperature thermal polymerization, resulting in the formation of N-doped graphene. This N-doped graphene can be grafted onto the terminal amino group, forming a potential electron transfer pathway. Additionally, N-doped graphene, because of its good electrical conductivity, guides the photogenerated electrons toward the anchored Rh sites. The catalyst achieves exclusive regeneration of 1,4-NADH with only a 0.12% Rh atomic ratio and realizes 80% NADH regeneration in 20 min. The competitive relationship between hydrogen production and NADH regeneration is also elucidated. Combined with formate dehydrogenase immobilized on a hydrophobic membrane, CO2 reduction to formate is accomplished efficiently, and the formate concentration can accumulate to 7 mmol L-1 within 48 h.

Key words: Bioinspired metalation, NADH regeneration, Photoenzyme-coupled catalysis, CO2 reduction, Charge transfer