[New Energy Applications] – “Photoactive” graphene material that can be used in fuel-free spacecraft

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Tianjin, June 19 (China Youth Daily·Zhongqing Online reporter Zhang Guo; correspondent Wu Junhui) – After three years of research, a research team from Nankai University has developed a special type of graphene material that can enable flight when exposed to various light sources, including sunlight. The driving force generated by this material is more than a thousand times greater than that of traditional photonic pressure. This research achievement makes \"opto-mechanical\" flight possible. Currently, almost all aviation and space flights rely on chemical propulsion, that is, they use burning chemicals to generate thrust; directly driving flight with light has been a dream of the scientific and aviation communities for many years. The issue of power sources has always prevented humanity from going further. On June 15, a paper by a research team led by Professor Chen Yongsheng from the School of Chemistry and Professor Tian Jianguo from the School of Physics at Nankai University was published online in the journal Nature Photonics. In numerous previous studies, scientists have attempted to use \"light pressure\" to generate power. “\"Light pressure\" is the pressure generated by light falling on an object. Photons possess both mass and velocity; the light pressure generated when a large number of photons with momentum strike an object causes the object to move. However, the driving force from light pressure is minuscule and far from sufficient to meet the load requirements of aviation and aerospace. The graphene material developed by Professor Chen Yongsheng’s team can be effectively driven to fly under the illumination of various light sources, including sunlight, thanks to the combined effect of the special morphological structure of this macroscopic material and the unique electronic structure of graphene itself. In the Key Laboratory of Functional Polymer Materials of the Ministry of Education, located at Nankai University, researchers placed a 4-milligram sponge-like, disc-shaped three-dimensional graphene material into a vacuum tube. Driven by different light sources, the \"sponge\" instantly moves horizontally or vertically, with a maximum displacement of up to 40 centimeters. The researchers explained that the light sources used in the experiments were all weak, such as ordinary lasers and xenon lamps. Experiments have shown that the wavelength of the light source is inversely proportional to the driving force generated by the graphene material. That is, the shorter the wavelength, the greater the driving force generated by the material. Through outdoor experiments, researchers found that sunlight can also drive this graphene material to move. “This is what we have learned: for the first time in the history of science, light has been used to propel a macroscopic object, achieving macroscopic propulsion. ”Professor Chen Yongsheng said that, through quantitative measurements, the force generated by this graphene material under light exposure is more than a thousand times that of conventional photonic pressure. “Through calculations, for a load of 500 kilograms, using drive sails fabricated from this graphene-based material, the driving force generated theoretically can provide an acceleration of at least 0.09 meters per second. ” In addition to observing that this light directly drives flight, the research team, through numerous experiments, proposed a new driving mechanism: under the influence of light, this material generates a corresponding driving force by emitting a large number of electrons; in other words, this special form of propulsion is achieved through electron ejection, which is completely different from traditional chemical rockets. Currently, Professor Chen Yongsheng’s team is conducting further research and verification on this mechanism. Therefore, this material can also serve as a convenient electron emission source. This work also suggests that other materials with structures similar to the Dirac band may obtain similar properties and capabilities through appropriate assembly. A review article published in the UK’s renowned popular science magazine New Scientist in its latest issue on this achievement states that it \"adds another amazing property to graphene, this excellent material.\" ”