Gram-scale synthesis of ultra-fine Cu₂O for highly efficient ozone decomposition

Nowadays, it is necessary and challenging to prepare Cu₂O in a large scale for various applications such as catalysis due to its excellent properties. Here, gram-scale Cu₂O with nm size is successfully prepared using a simple liquid-phase reduction method at 25 °C. The amount of NaOH is found to be the key factor to determine the particle size of Cu₂O by modifying the complexation and reduction reactions. The obtained ultra-fine Cu₂O exhibits high performance of >95% efficiency for removing high-concentration (3000 ppm) ozone at 25 °C and even at a high relative humidity (RH) of 90% for more than 8 h. Furthermore, the Cu₂O nanoparticles are coated onto an aluminium honeycomb substrate to form a monolithic catalyst, which shows high ozone removal efficiency of >99% in dry air and >97% in 90% RH for >10 h at a space velocity of 8000 h^-1. The high performance could be attributed to the enhanced release of the ozone decomposition intermediate by the small size of Cu₂O, as verified by O₂ temperature-programmed desorption and X-ray photoelectron spectroscopy. All these results show the industrial promise of the large scale synthesis of ultrafine Cu₂O applicable for high-performance ozone removal.