<p>A flower-like microsphere g-C₃N₄/Bi₂MoO₆ S-scheme heterojunction was successfully constructed, and its photocatalytic performance in the Cr(VI) reduction was investigated under visible light. The g-C₃N₄/Bi₂MoO₆ sample with a mass ratio of 10% showed the fastest reduction rate with a rate constant of 0.1203 min⁻¹, which was 9 and 5 times higher as compared with pure g-C₃N₄ and Bi₂MoO₆, respectively. Moreover, the g-C₃N₄/Bi₂MoO₆ sample exhibited excellent stability in the process of cyclic experiments. The photocurrent response and EIS analysis implied that the g-C₃N₄/Bi₂MoO₆ sample possessed a higher separation efficiency of photogenerated electron–hole pairs. Scavenger experiments and EPR measurements demonstrated that e⁻ and ⋅O₂⁻ are the major reactive species in photocatalytic reduction of Cr(VI) for g-C₃N₄/Bi₂MoO₆ sample. The S-scheme heterojunction formation between the g-C₃N₄ and Bi₂MoO₆ promoted the separation of photogenerated charge carriers, thus forming more active species, which is the reason for the enhanced photocatalytic activity of the g-C₃N₄/Bi₂MoO₆ sample.</p> Graphical abstract <p></p>