Chitosan as a promising hole-scavenger for photoelectrochemical monitoring of cobalt(II) ions in water

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2019-10, Vol.851, p.113470, Article 113470
• Main Authors: Zheng, Chenyan, Li, Baichuan, Hong, Chengyi, Peng, Aihong, Chen, Xiaomei
• Format: Article
• Language: English
• Subjects: Chelating agent; Chelating agents; Chelation; Chitosan; Cobalt; Cobalt(II) ions; Electromagnetic absorption; Fluorine; Natural polymers; Photoelectric effect; Photoelectric emission; Photoelectrochemical sensor; Reagents; Tin oxides; Tungsten oxides; Tungsten trioxide
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2019.113470

In this work, a traditional and natural polymer, chitosan (CS) is reported as an efficient hole-scavenger that enhances the photoelectrochemical (PEC) properties of tungsten trioxide (WO3) for Co2+ detection in water. Decoration of WO3/fluorine-doped tin oxide (FTO) electrodes with CS remarkably improves the visible-light absorption and enhances the photo electron–hole separation efficiency of WO3, giving rise to significant photocurrent enhancement. Moreover, by taking the advantage of the strong chelating ability of CS, Co2+ can be extracted effectively from water by using the CS/WO3/FTO material. The introduction of Co2+ prevents CS from consuming the oxidative holes, resulting in a decrease of the photocurrent. Enlightened by this, we developed a sensitive and selective PEC method for tracing of Co2+ in the range of 1.0 to 60.0 μmol L−1, with a detection limit of 0.3 μmol L−1 (S/N = 3). In addition, based on a systematic study, we proposed a possible mechanism for the PEC process on CS/WO3/FTO. This work may provide new insight into the use of natural polymers as electron donors and specific chelating agents in PEC sensors, in addition to expanding the application of the PEC approach in the field of environmental and biological analysis. [Display omitted] •Chitosan acted as a novel hole-scavenger to enhance the PEC properties of WO3.•Chitosan functioned as a chelate to effectively extract Co2+ from water.•A sensitive and selective PEC method was established on the basis of CS/WO3/FTO.•The proposed PEC approach was successfully used to analyze Co2+ content in water.