Electrochemically decorated gold nanoparticles on CVD graphene ChemFET sensor for the highly sensitive detection of As(III)

•A reusable receptor-free ChemFET sensor was developed for As(III) detection.•The properties of the AuNPs-Gr sensing channel were characterized.•A method for As(III) detection based on electrochemical doping was proposed.•The sensing mechanism of the sensor was investigated.•The concentration of As(III) can be detected as low as 1.0 ppt.