A photo-switch for enzymatic biofuel cells based on the photo-oxidization of electron acceptor in cathode by C-dots nanozyme

Abstract Enzymatic biofuel cells (EBFCs) are a promising green power source due to their merits of using renewable bio-fuels, environmentally friendly bio-catalysts and mild operating condition. For the practical point of view, it is necessary to tune the power output of the cell according to the electric device of interest. However, current approaches that are based on pH- or temperature-sensitive materials and enzymes in anode or the alteration of conductivity in the cathode face several challenges. In this article we designed a novel photo-switch based on the photo-oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the cathode catalyzed by C-dots nanozymes. As the first photo-switch adopting a cathode-controlled strategy, it achieved rapid, sensitive, and repeatable regulation of EBFC current and the power density with the designed working mechanism. After systematically optimizing the concentration of C-dots and TMB as well as the current collector area, the current of the EBFC equipped with the photo-switch rose from 2.3 to approximately 9 μA and the power density increased from 2.8 to 35 μW cm−2 after the 20 min of blue light irradiation, which is an improvement over most reported switches. Thus, this photo-switch makes it possible to adjust the power output of the EBFCs according to the specific photo signal and promotes “smart” EBFC applications.