Comparative study of different polyatomic ions of electrolytes on electricity generation and dye decolourization in photocatalytic fuel cell

• Published in: Journal of water process engineering 2020-10, Vol.37, p.101479, Article 101479
• Main Authors: Ong, Yong-Por, Ho, Li-Ngee, Ong, Soon-An, Banjuraizah, Johar, Ibrahim, Abdul Haqi, Lee, Sin-Li, Nordin, Noradiba
• Format: Article
• Language: English
• Subjects: Conductivity; Degradation; Electrolytes; Photocatalytic fuel cell (PFC); Polyatomic ions
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2020.101479

[Display omitted] •Interface interaction between ZnO/Ni with RR120 was explored.•The supporting electrolytes could reduce the internal resistance (higher Jsc).•Higher charge number of polyatomic ions led to higher energy recovery efficiency.•SO42- was more efficient than PO43- in cleavage of aromatic compounds.•Excellent stability and reusability of ZnO/Ni photoanode achieved in 5 cyclic runs. Developing an effective interface interaction between photoanode and electrolyte is crucial for achieving superior photocatalytic fuel cell (PFC) performance. In this aspect, the contribution of the medium or electrolyte properties in the PFC system such as dye concentration, ionic nature and active radicals play a decisive role. Herein, we constructed a PFC with ZnO loaded nickel foam (ZnO/Ni) photoanode to study the influence of initial dye concentration, pH and supporting electrolytes of different polyatomic anions on the PFC performance. The optimum initial dye concentration and pH for the PFC with reactive red 120 as organic pollutants were found to be 30 mg L−1 and 7.5, respectively. The PFC performance can be synergistically enhanced by the addition of three types of polyatomic anions (Na3PO4, Na2SO4 and NaNO3) as supporting electrolytes. In turn, PO43- had the greatest influence on the reduction of internal resistance (highest short circuit current, Jsc) which corresponded to the conductivity of dye solution. Eventually, the higher charge of polyatomic ions could contribute to higher energy conversion efficiency in PFC. Nonetheless, SO42- anions favoured the cleavage of aromatic compounds by the advantage of recycling between SO42- and SO4- through hole scavenging activity. Comprehensively, our findings provided new insight into the selection of supporting electrolyte as well as the proposed mechanism of active radicals involved in PFC. Additionally, the ZnO/Ni photoanode demonstrated its excellent recyclability as it retained high PFC performance after five consecutive runs.