[1] He is known for significant contributions to the discovery and research of photocatalytic and superhydrophilic properties of titanium dioxide (TiO2), which is also known as the Honda-Fujishima effect.

In 1967, while working on his Ph.D. under the supervision of professor Kenichi Honda (本多 健一), he discovered the phenomenon of photocatalytic water decomposition (water photolysis) when he exposed a titanium dioxide electrode to strong light, later called the Honda-Fujishima effect.

[citation needed] In 1999 he was founder editor-in-chief of the editorial panel of the Journal of Photochemistry and Photobiology C: Photochemistry Reviews[6] In 2001, he was nominated vice president of the Chemical Society of Japan,[citation needed] becoming its president in 2006.

[5] In 2002 he was research supervisor for the development of advanced nanostructured materials for energy conversion and storage at the Japan Science and Technology Agency (JST).

[5] In 2012 he received the Laurea Honoris Causa in chemistry of the environment from the University of Turin.