CoOOH nanosheets-coated g-C3N4/CuInS2 nanohybrids for photoelectrochemical biosensor of carcinoembryonic antigen coupling hybridization chain reaction with etching reaction

•A signal-on photoelectrochemical biosensor was developed for the detection of CEA.•Semiconductor materials (g-C3N4/CuInS2 and CoOOH) with low toxicity were selected as the signal tags.•Target-triggered hybridization chain reaction and hydrolyzate-induced etching reaction were used for the signal amplification.