Electrospun graphene-cellulose acetate/Paulschulzia pseudovolvox (Algae) modified photoelectrodes generating electricity via harnessing solar energy: A novel biosensing design for photoelectrochemical pesticide detection via photosynthesis inhibition

Abstract

This article explores the possibility of biophotovoltaic devices (BPVs) as a sustainable solution to the global energy issue and climate change mitigation. BPVs produce renewable power by harnessing sunshine and water, employing the photosynthetic processes of biological photocatalysts such as green algae and cyanobacteria. Carbon-based electrodes, particularly graphene (Gr), are distinguished as advantageous alternatives owing to their affordability, electrical conductivity, and mechanical robustness. While reduced graphene oxide is frequently utilized, non-oxidized graphene has not been extensively studied until recent researches emphasized its remarkable current-harvesting abilities. Moreover, one-dimensional structured nanomaterials, such as electrospun nanofibers, present opportunities for enhancing electron transit and augmenting charge collecting efficiency. A novel photoanode design has been developed, using Paulschulzia pseudovolvox sp. (green algae) immobilized on a graphene-cellulose acetate electrospun matrix. This mat offers a porous structure that facilitates suitable algal attachment and effective electron transfer. The cathode is linked to a gold electrode surface coated with Poly (4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzamine), P(SNS-NH₂) electrochemically, on which the bilirubin oxidase (BOx) enzyme gets immobilized via glutaraldehyde activation. The algae-based system employs light to oxidize and dissociate water at the photoanode, producing oxygen. At the same time oxygen is converted to water at the cathode through bioelectrocatalysis. Optimizations were carried out to improve electron transport and promote electron transfer, hence achieving high photocurrent. Under optimal conditions, the BPV attained a peak power output of 55.2 mW/m² at a steady state with a current density of 125 mA/m². In addition to conversion of light energy to electricity, the system was applied as a pesticide biosensor. The BPV system effectively detected atrazine and diuron, with analytical characterisation performed for atrazine within the 0.1–1.2 μM range and diuron within the 0.01–0.15 μM range. The detection limits were significantly low, measuring 7.5 nM for atrazine and 0.29 nM for diuron. Furthermore, recovery studies were also performed to evaluate the pesticide biosensor capabilities of BPV.