Abstract: Treatment of heavy metal pollution is challenging, and hence, is the focus of tackling environmental problems. Photocatalysis-based technologies provide a green and sustainable route to heavy metal removal. TiO$_{2}$ is regarded as the most suitable photocatalyst because of its unique photo- and electrochemical performances. However, its application under visible light and natural sunlight is limited due to its large band gap and high carrier recombination rate. This review summarises a series of photo catalysts that have been developed in the recent years for heavy metal removal. Strategies for improving the photocatalytic activity of TiO$_{2}$, which involve surface modification, metal/non-metal doping, immobilisation, and coupling with other semiconductors, were summarised; the corresponding reaction mechanisms were also discussed. Moreover, the status and drawbacks of the current research on the photocatalytic removal of heavy metals were critically discussed.

Key words: heavy metal, photocatalysis, TiO₂