The development of efficient and stable catalysts for advanced oxidation processes (AOPs) is of increasing interest for water purification. In this study, commercially available NiO microparticles were employed as an effective catalyst for the activation of peroxydisulfate (PDS) to degrade bisphenol A (BPA). Comprehensive physicochemical characterization confirmed that NiO possessed morphology of aggregated microparticles, coexisting Ni²⁺/Ni³⁺ oxidation states, and abundant surface oxygen vacancies, which are favorable for activating PDS. Under optimized conditions, the NiO/PDS system exhibited a degradation efficiency of 93.2% and a mineralization rate of 82.96%. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that both radical and non-radical pathways were involved in the degradation process, where radical pathway played a minor role and non-radical pathway played a dominant role. The system demonstrated sufficient resistance to anion interference, pH variation, and humic acid presence, and exhibited a selective degradation for the target pollutant BPA. Furthermore, application to real pharmaceutical wastewater further confirmed the practical applicability of the NiO/PDS system, and a bio-toxicity assessment using the Ecological Structure Activity Relationships (ECOSAR) model predicted a substantial reduction in ecological risk of BPA solution after the treatment by the system.

How to regulate the supramolecular structures in the assembly of graphene quantum dots (GQDs) is still a great challenge to be overcome. Herein, the GQDs of 1-3 layers with high quality are synthesized from the new precursor m-trihydroxybenzene in a green method. More importantly, a strategy for designing the supramolecular structures of GQDs is demonstrated, and the novel supramolecular morphologies of GQDs have been constructed for the first time. Moreover, the supramolecular morphologies of GQDs can be well controlled by regulating the preparation conditions, and the formation mechanism of the branch-like supramolecular structure has been explained by the the diffusion-limited aggregation (DLA) model. This work not only develops a new precoursor to synthesize GQDs, but also opens up an effective route to form the polymorphic supermolecules, thus greatly facilitating their potential applications.