Triboelectric-photocatalytic coupling enhanced photogenerated electrons and holes utilization for efficient algal inactivation

Algal blooms have become a challenging problem in conventional water treatment processes due to numerous negative effects on human health and ecosystems. Photocatalysis has turned out to be a promising solution with the environmental and economic benefits beheld, but the rapid recombination of photogenerated electron and hole inhibited the application in practice. This study proposed a rotating triboelectric nanogenerator (R-TENG) as a self-powered bias for photocatalysis to enhance the algal removal efficiencies. R-TENG harvest waste water wave energy from coagulation tank to convert it into stable DC voltage (31 V) and DC current (27 μA). TiO2 nanotubes (TNT) serving as the anode in the photocatalysis with TENG system achieved complete inactivation of algae (>97%) after 7 h of reaction, which was increased by 13.9% compared with photocatalysis. This enhanced performance was attributed to the improvement of active species generation (e.g., •O2-, •OH and h+). During algal inactivation, the active species destroyed photosynthetic activity (decline of Chlorophyll a), antioxidant system (decrease of superoxide dismutase, catalase and malondialdehyde) and membrane in algal cells. Given the ubiquitous existence of algal cells in surface water, this work offers a novel method to develop high-performance electro-assisted photocatalysis for algal removal.