Photochemical conversion of oxalic acid on heterojunction engineered FeWO4/g-C3N4 photocatalyst for high-efficient synchronous removal of organic and heavy metal pollutants

Refractory organic and heavy metal contaminants have aroused increasing attention because of their high toxicity and degradation-resistant. Photochemical conversion of oxalic acid (OA) into active radicals on Fe-based photocatalysts, displaying unprecedented surface Fenton activity for the synchronous removal of organic and heavy metal pollutants, shows great application potentials. Herein, we reported a S-scheme FeWO4/g-C3N4 (FWO/CNS) heterojunction associated with OA activation exhibited unprecedented catalytic performance for cooperative removal of Rhodamine B (RhB) and Cr(Ⅵ). Density functional theory (DFT) calculations manifested the elaborate design of S-scheme FWO/CNS heterojunction could accelerate the separation of photoinduced carriers driven by built-in electric field. Experimental results confirmed that S-scheme FWO/CNS heterojunction could efficiently activate OA to generate abundant active species and the catalytic degradation rates toward RhB and Cr(Ⅵ) were 5 and 4 times than that of the absence of OA, respectively. These findings provide an insight comprehending to internal relationship between OA activation and photocatalyst, and further inspire us to design highly efficient OA-catalyst systems for environmental remediation.