PSII as an in vivo molecular catalyst for the production of energy rich hydroquinones - A new approach in renewable energy

One of the pertinent issues in the field of energy science today is the quest for an abundant source of hydrogen or hydrogen equivalents. In this study, phenyl-p-benzoquinone (pPBQ) has been used to generate a molecular store of hydrogen equivalents (phenyl-p-hydroquinone; pPBQH2) from thein vivo splitting of water by photosystem II of the marine cyanobacterium Synechococcus elongatus BDU 70542. Using this technique, 10.8 μmol of pPBQH2 per mg chlorophyll a can be extracted per minute, an efficiency that is orders of magnitude higher when compared to the techniques present in the current literature. Moreover, the photo-reduction process was stable when tested over longer periods of time. Addition of phenyl-p-benzoquinone on an intermittent basis resulted in the precipitation of phenyl-p-hydroquinone, obviating the need for costly downstream processing units for product recovery. Phenyl-p-hydroquinone so obtained is a molecular store of free energy preserved through the light driven photolysis of water and can be used as a cheap and a renewable source of hydrogen equivalents by employing transition metal catalysts or fuel cells with the concomitant regeneration of phenyl-p-benzoquinone. The cyclic nature of this technique makes it an ideal candidate to be utilized in mankind's transition from fossil fuels to solar fuels. •Phenyl-p-benzoquinone is used to store hydrogen equivalents through the in vivo splitting of water by PSII of S. Elongatus.•10.8 μmol of hydrogen equivalents (pPBQH2)/mg chl a/min was extracted using this process exhibiting very high efficiency.•The process exhibited stability in producing hydrogen equivalents over longer periods of time.•The precipitation of the desired product (phenyl-p-hydroquinone) obviates the need for costly downstream processing.