Mass-produced flexible Br doped PEDOT modified carbon paper electrodes for constructing mercury ion photoelectrochemical sensor.

• Br doped PEDOT modified carbon paper electrode is constructed through situ thermal polymerization. • The photocurrent of Br doped PEDOT was enhanced due to the doping of Br. • Br doped PEDOT was adopted as photoactive material the first time and was applied in PEC. • The as-prepared electrode can be volume production with good reproducibility. • The constructed Hg2+ PEC sensor exhibited speedy response, outstanding stability, excellent selectivity, wide linear range. Mercury (Hg) is a kind of the most common heavy metals with high toxicity in nature, existing in water, soil, and even food. Hence, it is of great importance to develop a simple, effective way to detect Hg2+. Flexible sensing has attracted extensive attention in recent years, which can be flexibly applied in various detection environments. Poly(3,4-ethylenedioxythiophene) (PEDOT) with conjugation structure which can accelerate the transfer of electrons and inhibit the recombination of carriers is favorable to the photoelectrochemical (PEC) process. Here, Br doped PEDOT modified carbon paper with narrower bandgap was firstly fabricated through situ thermal polymerization which exhibited high photocurrent intensity under visible-light irradiation. The success synthesis of PEDOT was confirmed by SEM, XPS, FT-IR and Raman spectrum. Meanwhile, the as-prepared electrode can be mass produced with good reproducibility. Based on excellent performance of as-prepared electrode of Br doped PEDOT/carbon paper, we constructed a PEC sensing platform for Hg2+ detection with the detection limit of 0.3 nM and linear range from 1 nM to 450 nM. In addition, the PEC sensor exhibited speedy response, outstanding stability, excellent selectivity, wide linear range, and was used for determination of Hg2+ in river water samples with recover range of 97.7–104.5 % and RSD of 2.8–4.7 %. [ABSTRACT FROM AUTHOR]