Smart Paper Transformer—New Insight for Enhanced Catalytic Efficiency and Reusability of Noble Metal Nanocatalysts

Although noble metal nanocatalysts show superior performance to conventional catalysts, they can be problematic when balancing catalytic efficiency and reusability. In order to address this dilemma, we for the first time developed a smart paper transformer (s-PAT) to support nanocatalysts, based on easy phase conversion between paper and pulp. The pulp phase was used to keep high catalytic efficiency of nanocatalysts and the transformation to paper enabled their high reusability. Herein, as an example of the smart paper transformers, a novel chromatography paper-supported Au nanosponge (AuNS/pulp) catalyst through a simple water-based preparation process was developed for the successful reduction of p-nitrophenol to demonstrate high catalytic efficiency and reusability of the noble metal nanocatalyst/pulp system. The composition, structure, and morphology of the AuNS/pulp catalyst were characterized by XRD, TGA, FE-SEM, ICP, TEM, FT-IR, and XPS. The AuNS/pulp catalyst was transformed into a pulp phase during the catalytic reaction and into the paper phase to recover catalysts after use. Owing to this smart switch of physical morphology, the AuNS/pulp catalyst was dispersed more evenly in the solution. Therefore, it exhibited excellent catalytic performance for the p-nitrophenol reduction. Under optimal conditions, the conversion rate of p-nitrophenol reached nearly 100% within 6 min and the k value of AuNS/pulp (0.0106 s-1) was more than twice that of a traditional chromatography paper-based catalyst (0.0048 s-1). Additionally, it exhibited outstanding reusability and could maintain its high catalytic efficiency even after fifteen recycling times. Accordingly, the unique phase switch from this smart paper transformer enables Au nanosponges to transform into a highly efficient, recoverable, and cost-effective multifunctional catalyst. The paper transformer can support various nanocatalysts for a wide range of applications, thus providing a new insight to maintain both high catalytic efficiency and reusability of nanocatalysts in the fields of environmental catalysis and nanomaterials.