Insight into the Morphology-Dependent Catalytic Performance of CuO/CeO2 Produced by Tannic Acid for Efficient Hydrogenation of 4-Nitrophenol

The construction of a heterogeneous nanocatalyst with outstanding catalytic performance via an environmentally benign and cost-effective synthetic category has long been one of the challenges in nanotechnology. Herein, we synthesized highly efficient and low-cost mesoporous morphology-dependent CuO/CeO2-Rods and CuO/CeO2-Cubes catalysts by employing a green and multifunctional polyphenolic compound (tannic acid) as the stabilizer and chelating agent for 4-nitrophenol (4-NP) reduction reaction. The CuO/CeO2-Rods exhibited excellent performance, of which the activity was 3.2 times higher than that of CuO/CeO2-Cubes. This can be connected with the higher density of oxygen vacancy on CeO2-Rods (110) than CeO2-Cubes (100), the oxygen vacancy favors anchoring CuO species on the CeO2 support, which promotes the strong interaction between finely dispersed CuO and CeO2-Rods at the interfacial positions and facilitates the electron transfer from BH4- to 4-NP. The synergistic catalytic mechanism illustrated that 4-NP molecules preferentially adsorbed on the CeO2, while H-2 from BH4- dissociated over CuO to form highly active H* species, contributing to achieving efficient hydrogenation of 4-NP. This study is expected to shed light on designing and synthesizing cost-effective and high-performance nanocatalysts through a greener synthetic method for the areas of catalysis, nanomaterial science and engineering, and chemical synthesis.