Bismuth Vanadate/Bilirubin Oxidase Photo(bio)electrochemical Cells for Unbiased, Light‐Triggered Electrical Power Generation

The construction of bias‐ and donor‐free photobioelectrochemical cells for the generation of light‐triggered electrical power is presented. The developed oxygen reduction biocathodes are based on bilirubin oxidase (BOD) that originates from Myrothecium verrucaria (MvBOD) and a thermophilic Bacillus pumilus (BpBOD). Methods to entrap the BOD with 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) redox molecules in a polydopamine layer are presented. A pH‐independent, positively charged pyrenebetaine linker was synthesized, utilized, and led to a threefold improvement to the bioelectrocatalytic current. Both the developed polydopamine/ABTS/MvBOD and the pyrenebetaine/BpBOD biocathodes were further coupled with BiVO4/cobalt phosphate water‐oxidation photoanodes to construct biotic/abiotic photobioelectrochemical cells, which generated power outputs of 0.74 and 0.85 mW cm−2, respectively. The presented methods are versatile, show the strength of biotic/abiotic hybrids, and can be further used to couple different redox enzymes with electrodes. Unbiased: A BiVO4 photoanode and photocathodes based on bilirubin oxidase variants are developed for bias‐ and donor‐free electrical power generation. The different electron transfer pathways between the thermostable Bacillus pumilus or the Myrothecium verrucaria bilirubin oxidase with the electrodes are investigated. The developed biocathodes are further coupled to a BiVO4 photoanode to construct a biotic/abiotic photoelectrochemical cell.