3D-printable scaffolds via DIW from ceramic pastes of ZnO nanoparticles without organic binders and their application as reusable photocatalysts for the degradation of Bisphenol A

Direct ink writing (DIW) is an efficient and cost-effective additive manufacturing technique for fabricating ceramic architectures. Zinc oxide nanoparticles (ZnO_NP) are promising photocatalysts due to their chemical stability, low toxicity, and high efficiency. However, the development of DIW-printable ZnO_NP-based pastes remains limited. This work presents the first systematic study to successfully develop 3D-printable ZnO_NP-based ceramic pastes (63 wt% solids) without organic binders. A solvent:co-solvent system (deionized water:ethylene glycol) and silica nanoparticles as inorganic binders enabled the fabrication of robust and self-supporting ZnO_NP-based scaffolds under an optimal formulation window. The photocatalytic potential was demonstrated through Bisphenol A degradation, achieving 95–85 % degradation over successive cycles, including post-reactivation. Unlike conventional powder-based photocatalysts, 3D-printed scaffolds allow efficient recovery and reuse, offering a sustainable alternative for environmental remediation. This novel approach pioneers DIW-printable ZnO_NP-based pastes without organic binders, paving the way for future advancements in photocatalytic applications and additive manufacturing of functional ceramics.