In Situ Catalytic Activity of CuO Nanosheets Synthesized from a Surfactant-Lamellar Template

CuO nanosheets approximately 0.8 nm thick were synthesized under ambient conditions within a few hours using a surfactant lamellar mesophase as a soft template. In aqueous media, metal ions and anionic surfactants form a lamellar mesophase. In the lamellar layers, metal ions can crystallize without structural collapse. Highly ordered CuO nanosheet/surfactant lamellar layers formed in an aqueous solution can be easily delaminated by washing with water. The use of the delaminated CuO nanosheet catalyst instead of traditional metallic catalysts resulted in a reduction reaction of 4-nitrophenol with NaBH₄ that obeyed zero-order kinetics. This indicates in situ conversion of CuO to Cu in the reaction solution. Cu in situ reduced by BH⁻ ₄ acted as a catalyst relaying electrons for the reduction of 4-NP. The catalytic reaction was investigated by UV-vis spectroscopy, and the reduction and crystalline structures of the nanosheets were analyzed by UV-vis spectroscopy and X-ray diffraction. These results indicate CuO nanosheets to be an attractive alternative to metal catalysts in reactions involving hydrogen.