Modulating photoinduced spatial charge separation by synergistic N/Cu dual-doped MgO-embedded CdS heterojunction for robust phenol degradation

Dissemination of phenolic compounds from environmental compartments is of hazardous concern that notably threatens individuals’ well-being. To tackle the pressing challenges posed by phenol-contaminated water bodies, the deployment of heterojunction photocatalysts has emerged as a promising and effective alternative, providing unparalleled rate and selectivity toward refractory contaminants. Herein, nitrogen-copper dual dopants were incorporated in situ onto the hexagonal MgO and spherical wurtzite CdS catalyst, constructing a novel N/Cu co-doped MgO/CdS (NCMC) heterojunction for the phenol decontamination. The structural, morphological and optical features of the NCMC heterojunction were thoroughly assessed by diverse characterizations, including XRD, FTIR, FESEM-EDS, TEM, BET, PL, EIS, Mott-Schottky, and DRS. The as-made NCMC material has a well-defined crystalline structure with reduced particle agglomeration, facilitating efficient charge migration to and from active sites and thereby enhancing phenol oxidation performance. The successful incorporation of N and Cu impurities in the NCMC heterojunction introduced mid-state defects. This resulted in band gap narrowing, increased active surface area (59.13 m² g − ¹), boosted the photogenerated carrier mobility, and prolonged carrier lifespan. h + and OH • radicals were verified to be dominant oxidative species in the catalytic degradation reaction by free radical quenching experiments. 93% of phenol degradation was achieved with a rate constant of 9.3×10 −3 min −1 by NCMC under optimal conditions, which is roughly two times greater than the N/Cu-MgO (NCM) nanocatalyst. Besides, the N and Cu dual-doped MgO/CdS heterojunction retained the photocatalytic rate over five consecutive runs with high selectivity (84%). Through the integration of Fermi level computations from the Mott-Schottky analysis, radical trapping experiments, and EIS, the interfacial charge relocation was systematically unraveled. Additionally, the probabilistic hazards of the purified and unpurified phenol media were explored via a HQ approach.