Atrazine is a widely used herbicide and a typical toxic pollutant. TiO2-mediated photocatalysis is an efficient way to degrade such a refractory contaminate. In a photocatalyic process, great charge separation and efficient interparticle electron transfer are highly desired and are usually achieved through element doping and phase junction optimization. However, in the traditional methods for synthesizing phase junction TiO2, high phase transition temperature and appropriate adjustors are always needed. In this work, boron-doped (B-doped) TiO2 with a tunable anatase/rutile ratio is successfully synthesized for efficient atrazine degradation by using a simple one-step calcination method, which is conducted below phase transition temperature with as-prepared Ti and B mixture as a precursor. The formation of the surface-phase junctions between anatase and rutile nanoparticles enables effective interparticle electron transfer and results in more efficient charge separation. Also, the B-doping serves as charge traps, which are able to mediate oxidative electron transfer. The prepared B-doped TiO2 exhibits a higher photocatalytic activity for the degradation of atrazine, with a reaction rate of 4 times faster than that of the non-doped counterpart. The photogenerated reactive species and degradation intermediates of atrazine are identified, and the photocatalytic atrazine degradation mechanism is elucidated. This study provides a new approach to prepare phase junction photocatalysts and demonstrates that the anatase/rutile ratio can be tuned by doping element. Such a "killing two birds with one arrow" strategy could be extended for preparing other photocatalysts for the degradation of various pollutants. (C) 2016 Elsevier B.V. All rights reserved.