BACKGROUND The non‐modified titanium dioxide (TiO2) nanotube (TNT) and silver (Ag)‐modified TNT samples were fabricated via an alkaline hydrothermal process. The synthesized samples had a high Brunauer–Emmett–Teller surface area since the resulted TNT was free of calcination, which is different from the traditional synthesized method. The specific surface area of non‐modified TNT and Ag‐modified TNT samples were 392 and 330 m2 g−1, respectively. RESULTS The results indicated that anatase phase, cubic silver chloride (AgCl) and Ag co‐existed in the Ag‐modified TNT sample. In contrast, non‐modified TNT sample has only anatase phase. The OH groups, pre‐adsorbed water, and oxygen vacancies can be found on the surface of all samples. The Ag‐modified TNT sample showed to have higher removal efficiencies than that of non‐modified TNT sample for gas‐phase elemental mercury, carcinogenic malachite green, crystal violet and mixtures of dyes. CONCLUSION Although specific surface area of non‐modified TNT was larger than that of Ag‐modified TNT, the Ag‐modified TNT possessed a high‐performance photocatalyst due to the electron‐hole pairs separation efficiency increase. © 2019 Society of Chemical Industry