Constructing hotspots through star-shaped gold-copper alloy nanocrystals for laser initiation of explosives

Laser initiation technology is an effective way to detonate high energy materials safely and reliably, which has broad application prospect in military blasting. However, there are many obstacles in high-power laser propagating through optical fiber, which directly affect the initiation of high-energy explosives under low-power conditions. Photosensitizer is a necessary substance for initiating low energy and low sensitivity explosives. Herein we developed gold-copper alloys nanocrystals as free-standing laser energy converter material to reduce the laser initiation threshold and delay time. By controlling the nanocrystals morphology, more hotspots were created in the nanocrystals and the ultraviolet–visible-near infrared (UV–VIS-NIR) absorption peak of nanocrystals was regulated to around 808 nm. The laser irradiation result showed that the temperature of the gold-copper alloys nanocrystals was close to 280 ℃ within 10 s (808 nm, 1 W·cm−2). In the practical applications, the cyclotrimethy lenetrinitramine (RDX) initiation threshold can be reduced by 83.47% and B/KNO3 delay time by 43.95% by using gold-copper alloy nanocrystals as laser energy absorber. This result indicates that the gold-copper alloy as an independent laser absorbing material can effectively initiate low-sensitive explosives under low-power conditions.