Hole-scavenging in photo-driven N 2 reduction catalyzed by a CdS-nitrogenase MoFe protein biohybrid system

• Published in: Journal of inorganic biochemistry 2024-04, Vol.253, p.112484
• Main Authors: Clinger, Andrew, Yang, Zhi-Yong, Pellows, Lauren M, King, Paul, Mus, Florence, Peters, John W, Dukovic, Gordana, Seefeldt, Lance C
• Format: Article
• Language: English
• ISSN: 1873-3344
• DOI: 10.1016/j.jinorgbio.2024.112484

The light-driven reduction of dinitrogen (N ) to ammonia (NH ) catalyzed by a cadmium sulfide (CdS) nanocrystal‑nitrogenase MoFe protein biohybrid is dependent on a range of different factors, including an appropriate hole-scavenging sacrificial electron donor (SED). Here, the impact of different SEDs on the overall rate of N reduction catalyzed by a CdS quantum dot (QD)-MoFe protein system was determined. The selection of SED was guided by several goals: (i) molecules with standard reduction potentials sufficient to reduce the oxidized CdS QD, (ii) molecules that do not absorb the excitation wavelength of the CdS QD, and (iii) molecules that could be readily reduced by sustainable processes. Earlier studies utilized buffer molecules or ascorbic acid as the SED. The effectiveness of ascorbic acid as SED was compared to dithionite (DT), triethanolamine (TEOA), and hydroquinone (HQ) across a range of concentrations in supporting N reduction to NH in a CdS QD-MoFe protein photocatalytic system. It was found that TEOA supported N reduction rates comparable to those observed for dithionite and ascorbic acid. HQ was found to support significantly higher rates of N reduction compared to the other SEDs at a concentration of 50 mM. A comparison of the rates of N reduction by the biohybrid complex to the standard reduction potential (E ) of the SEDs reveals that E is not the only factor impacting the efficiency of hole-scavenging. These findings reveal the importance of the SED properties for improving the efficiency of hole-scavenging in the light-driven N reduction reaction catalyzed by a CdS QD-MoFe protein hybrid.