Polyhedral Cu2O crystal: Morphology evolution from meshed nanocube to solid and gas-sensing performance

Previously, the formation of polyhedral Cu 2 O crystal is usually proposed like that the seed crystals grow outward following the relative growth rates (R values) along different directions ( Inside-out Pattern ) or that the surrounding building blocks aggregate toward the center followed by ripening ( Outside-in Pattern ). However, in this study, simply mixing aqueous Cu(CH 3 COO) 2 , NaOH, and D-(+)-glucose in the order listed at 70 °C for a period, a distinct growth manner of Cu 2 O polyhedron was observed based on carefully recording the solution color changes and the elaborate time-dependent SEM/TEM observations, which was referred to All-direction Pattern . More specifically, the initially formed Cu 2 O nanoshuttles first self-aggregated into porous braided structure with well-defined cubic framework and then condensed into solid cube from all direction via consuming the surrounding fragments everywhere possible, rather than in gradient densification from inside-out or outside-in. After that, the solid cube fell into the common Outside-in Pattern , i.e., adsorbing the surroundings followed by ripening. Although many complex polyhedral submicrostructures have been already reported, to our best knowledge, Cu 2 O crystal that grows in such manner is barely observed. It is believed that such interesting growth mechanism of polyhedral crystals could be general. What's more, the 30 min-Cu 2 O powder was made into a gas sensor towards ethanol, the performance of which has reached the level of application.