Photo(electro)catalytic Performance of ZnO‐Based Nanopowders Prepared through Pulse Alternating Current Electrosynthesis in Alkaline Earth Chloride Electrolytes

Abstract

Photo(electro)catalysis is a technology that allows abundant and clean solar energy to be harvested as an essential step to achieving sustainable development goals. However, controllable and economically viable synthesis of nanocatalysts is one of the key challenges that hinder the practical application of many important energy‐related photo(electro)catalytic reactions. In this study insights into the electrosynthesis of ZnO‐based materials using pulse alternating current as a green oxidant and the alkaline earth metal chloride aqueous solutions as electrolytes were provided. The effect of electrolyte on composition and structure of final products was demonstrated. ZnO photocatalyst prepared in BaCl2 exhibited different activity tendency in photoelectrocatalytic and photocatalytic systems showing the highest photocurrent (0.18 mA cm−2) for ZnO photoelectrode annealed at 300 °C and maximum rate constant for methylene blue dye photodegradation in the presence of ZnO particles annealed at 500 °C. Optimized ZnO nanopowder was further employed for the degradation of 2,4‐dinitrophenol pollutant in a custom‐designed flow photoreactor operating under low‐power UV. 2,4‐dinitrophenol was degraded to 90.1 % at ZnO dosage of 0.2 mg L−1 within 280 min of illumination. Overall, the optimization of pulse alternating current electrosynthesis and post‐annealing might be promising and sustainable approach to ZnO‐based nanopowders for environmental photo(electro)catalytic applications.