Highly sensitive photoelectrochemical detection of glucose based on BiOBr/TiO2 nanotube array p-n heterojunction nanocomposites

Well-crystallized TiO2 nanotube arrays (TNTA) were firstly prepared by anodization of titanium foils and subsequent heat treatment. Then BiOBr-TNTA composite electrodes were obtained through vacuum impregnation and chemical precipitation method. The BiOBr-TNTA nanocomposites were used as photoelectrochemical (PEC) electrodes for the detection of glucose. The matched energy levels of TNTA and BiOBr promote the separation of photoelectrons and holes effectively. The preparation conditions (e.g. Bi3+ concentration and TNTA thickness) of the BiOBr-TNTA electrodes and test conditions (e.g. pH value and bias voltage) affect the PEC detection properties significantly. Results show that the composite electrode exhibits the best properties for detecting glucose when the Bi3+ concentration is 10 %, the TNTA thickness is 6.9 mu m, the test electrolyte is 0.1 M NaOH and the applied bias voltage is 0.5 V. The BiOBr-TNTA electrode prepared under the optimal conditions has a minimum detection limit of 10 nM (S/N = 3) and a linear range of 5 x 10(2)-3 x 10(7) nM, which are much superior to the previously-reported PEC electrodes. The optimized BiOBr-TNTA electrode possesses high selectivity, excellent stability and good repeatability in detection of glucose. This work provides a new PEC electrode for non-enzymatic detection of glucose, which can be practically employed in real serum samples.