Ultra-Low Intensity Continuous Wave Laser Ablation Propulsion With Graphene-Engineered Wood

Conventional propellant materials, including polymers, metals, and doped polymers, have long been investigated for laser ablation propulsion, though achieving desired specific impulse values with low-intensity continuous wave laser irradiation remains a challenge. This study presents low-density graphene-delignified wood composites as novel, sustainable propellants for continuous-wave laser ablation propulsion. Experimental results show that natural wood achieves a density-specific specific impulse of 5043.0 ± 188 s g^-1 cm³, surpassing the performance of all previously reported conventional propellants. Graphene delignified wood improves the absorption of laser energy of natural wood by 98.61%, thereby achieving an ultra-low ablation threshold intensity of 0.54 MW m^-2; the lowest intensity attained so far, and an exceptional density-specific specific impulse of 1569.60 ± 57.40 s g^-1 cm³. The absolute specific impulse values of NW and GDW are 907.74 and 800.49 s, respectively, whereas no other material has achieved a value >100 s under CW laser irradiation. Additionally, graphene delignified wood has a tensile strength of 273.1 MPa, ∼10 times greater than NW, and a specific tensile strength of 533 MPa g^-1 cm³, exceeding common aerospace structural materials in strength-to-weight ratio. The findings unlock the potential of lightweight and sustainable graphene delignified wood for use in various light and space applications.