Photocatalytic fuel cell self-powered sensor for Cu2+ detection in water and soil: Signal amplification of biomass induced carbon-rich carbon nitride photoanode

The development of an accurate, selective, sensitive, and quantitative monitoring method for copper ion (Cu2+) in water and soil is crucial for addressing environmental pollution. Herein, a photocatalytic fuel cell self-powered sensor (PFC-SPS) platform was proposed by carbon-rich carbon nitride photoanode for Cu2+ determination. Carbon-rich carbon nitride is formed by replacing nitrogen atoms of tertiary nitrogen with carbon generated through the thermal decomposition of biomass chitosan. The carbon-rich structure enhances the pi delocalization in the carbon nitride skeleton, improving the optical absorption and accelerating the transmission of charge, endowing the photoanode with high and stable output signal. The formed Cu2+-aptamer complex increases the surface resistance of electrode, hindering the catalytic reaction of H2O2 oxidation and leading to the decrease in the output power density signal. This PFC-SPS platform detected Cu2+ with a wide range of 1.0 similar to 1.5 x 10(3) nM, a low limit of 0.40 nM, excellent selectivity, stability and accuracy for real river water and agricultural soil samples. It is expected that the platform can achieve low-cost and portable monitoring by a digital multimeter, and this work also proposes a strategy for detecting heavy metal ions based on the synergism of a photocatalytic fuel and self-powered platform.