Reduced graphene oxide modified Z-scheme AgI/BiMoO heterojunctions with boosted photocatalytic activity for water treatment originated from the efficient charge pairs partition and migration.

In order to enhance degradation of harmful organic pollutants like Rhodamine B (RhB) dye under visible-light irradiation (λ >420 nm), a silver iodide/reduced graphene oxide/bismuth molybdate (AgI/rGO/BiMoO) Z-scheme heterojunction photocatalyst was synthesized by a solvothermal process combined with an in-situ precipitation technique. The AgI (15 wt.%)/rGO/BiMoO (AGBMO-15) photocatalyst with a dosage of 0.5 g/L exhibited the highest photocatalytic activity with 98.0% RhB removal under an initial concentration of 10 mg/L within 30 min. This removal rate was approximately 65.8%, 57.7%, and 72.7% higher than that for a rGO/BiMoO (GBMO) binary composite, pure AgI powder, and pristine BiMoO nanoplates, respectively. The novel photocatalyst achieved approximately three times higher photocatalytic degradation within a shorter period of visible-light irradiation than pure BiMoO. Through photoluminescence analysis and trapping experiments, this outstanding performance was attributed to the efficient separation of photogenerated electron-hole pairs owing to an internal electric field at the contact interface of AgI and BiMoO, which generated more superoxide radical anions (•O) as primary reactive species to promote RhB degradation. Meanwhile, the rGO participated in the capture of visible-light and played a role of solid electronic medium at the AgI/BiMoO interface, which realized an effective Z-scheme electron transfer path, avoided the self oxidation of photocatalyst and prolonged the carrier life. Furthermore, the AGBMO-15 photocatalyst exhibited excellent photocatalytic degradation stability, maintaining an RhB removal rate of 96.2% after four cycles of reuse. Due to its simplicity, reusability, and controllability, the proposed photocatalyst has excellent application potential for the environmental remediation of wastewater.