Continuous-flow catalytic reactors based on 1d hydrogels for catalytic conversion and photocatalytic removal of organic materials in water

Contrasting with traditional batch-type reaction methodologies, continuous-flow chemistry introduces a transformative paradigm in heterogeneous catalysis, characterized by its advantageous features for industrial and environmental applications. In this study, we developed a novel approach to synthesize highly efficient continuous-flow reactors for water purification by integrating the principles of flow chemistry and nanocomposite hydrogels. Pd@AuAg trimetallic nanohybrids were synthesized with near-100 % yield by inducing the overgrowth of AuAg alloy nanoislands on a single Pd nanoplate, and further converted to Pd@AuAg–AgAuS metal-semiconductor nanohybrids through sulfidation. These nanohybrids were embedded within one-dimensional (1D) hydrogels housed in a transparent tube, forming internal channels for continuous flow. Through optimization of hydrogel cross-linking, channel architecture, and flow dynamics, the reactors demonstrated an impressive ability to convert 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a 96 % conversion rate using Pd@AuAg nanohybrids, and to degrade methylene blue (MB) with a 93 % efficiency using Pd@AuAg–AgAuS nanohybrids. Notably, these reactors have also exhibited outstanding stability, preserving over 95 % of their photocatalytic activity after 4 weeks of storage in a dried state. This work highlights the potential of continuous-flow reactors with tailored nanohybrids for environmental remediation and opens avenues for further advances in catalysis.