Non-enzymatic photoelectrochemical sensors based on Schiff base and chitosan co-decorated TiO2 nanosheets for dopamine detection

TiO 2 nanosheets (TiO 2 NSs) with a high percentage of {0   0   1} facets show high photoelectrochemical activity, but they only can utilize ultraviolet light due to the wide band gap. Thus, a new Schiff base monocrystal were synthesized and used to sensitize TiO 2 NSs. And then we constructed photoelectrochemical (PEC) sensors based on Schiff base sensitized TiO 2 NSs for dopamine (DA) detection. The sensitized TiO 2 NSs can extend the absorption spectrum range to the visible light region, and the photocurrent of the PEC sensors was increased by   one order of magnitude. Chitosan further decorated the sensors to enhance the selectivity. DA was oxidized by hole and covalently linked with chitosan. Subsequently, the DA oxide acted as electron acceptor to cause photocurrent quenching, enabling quantitative and selective detection of DA. The PEC sensors have wide detection range from 0.0005 to 5.0 mM with the detection limit (LOD) of 0.206 μM (S/N = 3). The non-enzymatic PEC sensors have a good selectivity which can distinguish DA from ascorbic acid (AA) and uric acid (UA), and also have reliable stability and recovery, thus, it has a good application prospect in biomedicine.