Photochemical ammonia production under ambient conditions remains a grand challenge. Here we demonstrate efficient visible-light fixation of N-2 to NH3 in water using novel two-dimensional (2D) Sb/TiO2 nanocomposites. Such hybrids afford a remarkable NH3 formation rate of about 20.8 mu mol h(-1) g(cat.)(-1), showing promise as photochemical materials for sustainable NH3 production.