A self-powered photoelectrochemical aptasensing platform for microcystin-LR cathodic detection via integrating Bi2S3 photoanode and CuInS2 photocathode

Although cathodic photoelectrochemical (PEC) analysis has inherently good anti-interference properties, the relatively insufficient number of holes and rapid recombination rate of carriers result in the relatively low sensitivity of PEC sensors; thus, an additional bias voltage is often required in practical applications. Herein, this study presents a self-powered PEC aptasensing platform to detect microcystin-LR (MC-LR) by integrating an n-type semiconductor Bi2S3 photoanode with a p-type semiconductor CuInS2 photocathode. Based on the difference between the Fermi levels of Bi2S3 and CuInS2, a large number of photogenerated electrons produced by the Bi2S3 photoanode can be supplied to the CuInS2 photocathode along an external circuit, effectively solving the problem of an inconspicuous photocurrent in the cathodic PEC analysis. The constructed sensor can detect MC-LR in the range from 10 fg/mL to 10 ng/mL with a low limit of detection of 9.0 fg/mL (S/N = 3). In addition to its high sensitivity, the aptasensing platform exhibited good anti-interference properties and reproducibility. The constructed self-powered PEC aptasensor can achieve highly efficient MC-LR determination without the addition of any electron donors or acceptors and does not require the application of an additional bias voltage, which uncovers new perspectives for the development of high-performance PEC sensors.