Combined photoelectrocatalytic techniques in water remediation

In recent decades, water pollution has become a serious concern, since it causes health risks to humans and other living organisms. Many water purification methods have been developed; among them, semiconductor photocatalysis has generated much interest for decontamination of polluted water. But, semiconducting photocatalytic materials suffer in wastewater treatment due to rapid recombination of photogenerated electron-hole pairs. To eliminate this shortcoming, photoelectrocatalysis (PEC) was developed. PEC is a promising method for treatment of wastewater containing a wide range of water pollutants. This chapter describes the fundamental mechanism and development of photoelectrocatalysis in the removal of organic (dyes, pesticide, and antibiotic), inorganic (metal/metalloid species, anions), and biological pollutants (bacteria and viruses) from water. The influence of experimental conditions, like light source, pH, initial concentration, bias potential, rotating speed of cathode, etc., on the removal of contaminants is highlighted. Improvement strategies such as doping processes and fabrication of composites for pure photoelectrode materials in water treatment are emphasized. Recent studies related to simultaneous removal of organic, inorganic, and pathogen pollutants by the PEC method are also discussed.