Oxygen vacancies and oxygen cycle of copper oxide enhancing the ignition and combustion behavior of boron particles

The combustion of boron (B) powder tends to generate a dense oxide layer on its surface, which severely impedes the sustained reaction. To solve the issue, the B modified by CuO (B-CuO) was prepared to utilize the facilitating effect of CuO on the combustion of nano-sized boron (nB) powder. To elucidate the phenomenon observed in laser ignition experiments, which CuO significantly improves the ignition and combustion performance of nB powder, thermal analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and density functional theory were employed. The results show that CuO enhances the heat release and reduces the ignition temperature of nB. The nB modified by CuO is capable of inducing a pre-ignition reaction and the maximum heat release is achieved when the CuO content reaches 30 wt.%. The oxygen vacancies on the CuO surface act as reaction sites, which promote the speed of the cyclic oxygen absorption and release process, and enhance the flame intensity. This study demonstrates the effectiveness of CuO in promoting the combustion of B powder and provides insight into the underlying mechanisms.