<p>In-situ synthesis of g-C₃N₄ containing nitrogen vacancies and cyano group via one-pot method using urea as the precursor. The structural, morphological or electrochemical properties of synthesized photocatalysts were characterized by XRD, BET analysis, TEM, FTIR, UV-DRS, PL, XPS and EPR. It was found that the nitrogen vacancy was successfully introduced into g-C₃N₄. Compared to pure g-C₃N₄, the (200) crystal plane in XRD of synthesized g-C₃N₄ showed slight red-shift, and the BET surface areas had changed from 27.5 to 35.7 m²<b>·</b>g⁻¹, which could provide more reaction center and active site. TEM confirmed that g-C₃N₄ and V_N-g-C₃N₄ were porous materials, and FTIR, XPS as well as EPR could prove the presence of nitrogen vacancies and cyano group. The UV-Vis absorption edge of V_N-g-C₃N₄ demonstrated briefly red-shift, PL intensity and lifetime of carriers declined in comparison with pure g-C₃N₄. Electrochemical test results showed that enhanced charge separation efficiency and low recombination rate of charge carriers of V_N-g-C₃N₄. The photocatalytic activity of the photocatalysts was researched by RhB degradation and ACT removal under visible light irradiation, the results showed the rate of RhB degradation on the V_N-g-C₃N₄ was 81%, which was 1.4-fold as high as that of g-C₃N₄ in visible light. The degradation contribution from the active species were h⁺ (67.3%) &gt;¹O₂(63.0%)&gt;•OH (49.4%) &gt;•O₂⁻ (20.3%) &gt; e⁻ (20.1%) &gt; H₂O₂(0.2%), and V_N-g-C₃N₄ exhibited excellent ACT removal rate, which was 1.6-fold higher than that of pure g-C₃N₄ in visible light. This study provides an efficient photocatalyst for the treatment of toxic wastewater.</p>