Sustainable Energy Conversion And Self-powered Sensing Applications Based On Enzymatic Biofuel Cells

Thanks to the vigorous development of electrochemistry,synthesis,and nanotechnology,enzyme biofuel cells(EBFCs)have made significant progress in systems,electrodes,and catalysts.Despite the great improvement in power output,from a few μW·cm-2 to mW·cm-2,EBFCs are still too poor to meet the energy demands of practical applications due to their inherent limitations.Therefore,the current research focus on EBFCs is no longer limited to increasing their power output.Instead,benefiting from their simple structure,extensive feedstock,low cost,and mild operating conditions,EBFCs can be developed in a variety of ways.Exploiting the unique advantages of enzymes,such as high selectivity,high specificity,and low overpotential may open the door to broad applications of EBFCs in both sustainable energy conversion and self-powered sensing applications.1.We have developed a bio-hybrid photoelectrochemical cell(BPEC)to implement direct and sustainable "solar-to-fuel-to-electric power" conversion,by systematically coupling the photoelectrochemical H2O2 generation and bioelectrochemical H2O2 consumption in a single compartment.Inside the BPEC,a dynamic circulation of H2I,H2O2,and O2 was established,without any additional fuels or sacrificial agents,thus making the BPEC intrinsically clean,simple,safe,and costeffective.Under visible light illumination,the BPEC exhibited an extraordinarily large open circuit potential of 1.03 V,and delivered a maximum power density of 0.18 mW·cm-2,which performed equally well even using seawater as electrolyte.2.We have presented an EBFCs-based self-powered biosensor(ESPB)for both electrochemical and colorimetric detection of formaldehyde pollutant,by employing formaldehyde dehydrogenase as bioanode and Prussian blue(PB)as electrochromic cathode.The developed ESPB exhibits desirable high sensitivity,low detection limit,and a broad linear range of 0.01-0.35 mM,covering the permissive level of formaldehyde in GB3880-2002 and the World Health Organization associated with environmental quality control.In special,the formaldehyde concentration can be precisely quantified by analyzing the color change of cathode digitally.In a spiked real sample test,the recovery ratios of formaldehyde with concentrations from 0.010 to 0.045 mM are determined to be between 95 and 100%by both measuring the short circuit current and analyzing the color change digitally,demonstrating the feasibility of the ESPB in practical applications.3.We report on a design of a naked-eye readout ESPB toward gaseous formaldehyde based on the good catalytic activity of the formaldehyde dehydrogenase bioanode to formaldehyde oxidation and the excellent electrochromic property of the PB cathode.The ESPB has a planar configuration and is covered with a thin film of gel electrolyte to provide an inner lateral resistance large enough to enable the progressive discoloration of the patterned PB at cathode,which in turn,making the determination of gaseous formaldehyde feasible by measuring the distance consumed.The ESPB shows obvious responses to gaseous formaldehyde in a broad concentration range of 80 to 3000 ppb,with good anti-interference ability to acetaldehyde and benzaldehyde.The ESPB also exhibits satisfying results in sensing gaseous formaldehyde released from the real plywood that is one of the dominant sources of the indoor gaseous formaldehyde.