This article comes from WeChat public account: Institute of Science (ID: kexuedayuan) , author: Li Qinglin (Qingdao Institute of bioenergy and Bioprocess Technology), drawing from the title The movie “Mars Rescue”
Because of its similarity to many characteristics of the earth, Mars has always been regarded as the preferred destination for future human migration to outer space.
If you want to immigrate to Mars, it is much more than flying from Earth to Mars. Humans want to achieve semi-permanent or permanent settlement on Mars, not just for a day trip to Mars, building a Mars base and ensuring that people are better on Mars. Survival is the key to whether you can emigrate to Mars.
Now, the food, clothing and housing in our lives are inseparable from a wide variety of chemicals, especially after the immigration to Mars in the future. It is certainly possible to transport materials across the planet, but the problems of low timeliness and high costs force people to find once and for all. Solution.
In this case, let ’s build a chemical plant on Mars!
Imagination Map of Mars Base (Image Source: Space X)
Mars chemical plant: mining raw materials
The chemical plants on the earth use the fossil resources of petroleum and coal as raw materials, through a variety of processes and processes, and with physical and chemical means to obtain a series of end products that are closely related to our production and life, such as plastics. , Medicines, fuels, including masks that are now in short supply worldwide.
So, to build a chemical plant on Mars, the first step is to go to Mars to mine!
Wait, before thinking about mining, what I want to tell you is that according to current scientific reports, there is no evidence that Mars ever had life forms such as plants or animals. At present, the scientific community generally believes that fossil resources are due to the long-term evolution of the remains of animals and microorganisms in ancient oceans or lakes in the stratum. Therefore, There are not necessarily mines under Mars .
Did the plan to build a chemical plant on Mars yet?Did you declare failure without starting?
Mars has not found any resources such as oil and coal, but does Mars really have nothing? Let’s take a look at what Mars has?
The scientific community generally believes that there is soil on the surface of the Martian body, there is ice under the surface, and there is a thin atmosphere. In addition, in 1969, Professor Pimentel of the University of Berkeley, through infrared detectors, found that the Martian atmosphere contains 96% CO > 2 and 4% of N 2 . If we really want to build a chemical plant on Mars, it seems that the only carbon substance CO 2 has become the only choice for chemical plant raw materials, that is, through CO 2 Preparation of polymer materials, fuels, pharmaceuticals and other chemicals necessary for life.
This idea sounds very fantasy, but it is not a fantasy. In fact, through artificial photosynthesis, all this can be achieved in the future!
Liquid sunlight: artificial photosynthesis system
No matter which planet humans emigrate in the future, how to survive better is particularly important. This is inseparable from chemicals such as polymer materials, drugs, fuels and fertilizers. So in 2003, the US Department of Energy launched the “Helios Project” at Berkeley National Laboratory, which aims to through learning from nature to construct a photosynthesis system, using semiconductors and catalysts, to convert CO 2 Convert into various chemicals.
Lawrence-Berkeley National Laboratory (Image source: google map)
In recent years, the team of academician Yang Peidong from Berkeley National Laboratory successfully built such a first integrated system using semiconductors and microorganisms in 2015, turning this vision intoA reality. Just recently, they launched a better “2.0 version”, that is, using silicon nanowires to capture solar photons and generate photo-generated electrons to provide them to the attached microorganisms. Finally, microorganisms absorb carbon dioxide, perform chemical reactions, and produce acetate, which achieves up to 3.6% solar energy conversion efficiency for a week.
This artificial photosynthesis system actually mimics the photosynthesis of plants and converts solar energy into chemical energy. Plant photosynthesis is to use absorbed sunlight to convert CO2 and water in the atmosphere into organic substances such as sugar for plants to carry out various metabolic activities. In fact, the coal, oil and natural gas we use also come from primitive plants. Energy accumulation.
comparison of natural photosynthesis and artificial photosynthesis (Source: Nat Commun. 2018, 9, 5003)
The artificial photosynthesis system is mainly composed of two parts, semiconductor and microbial engineering bacteria . Semiconductors are responsible for absorbing light energy and converting it into electrical energy. Engineering bacteria with specific functions use this energy to synthesize absorbed CO 2 into specific organic matter (Convert electrical energy to chemical energy) . At present, the utilization efficiency of solar energy by artificial photosynthesis can reach 8% to 10%, which is about 20 times higher than the photosynthesis efficiency of plants. In addition, the products it produces are not metabolized by bacteria like plants. Ensure a higher product yield.
So how does an artificial photosynthesis system that directly converts solar energy into chemical energy work?
Pandora ’s box: a magic weapon for the production of acetic acid
Taking the production of acetic acid as an example, acetic acid ( CH 3 COOH) , The scientific name acetic acid is an important organic chemical containing two carbons and the main component of vinegar. In the artificial photosynthesis system, the researchers selected anaerobic M. thermoacetica as the protagonist, and developed gold nanoclustered inorganic materials for light absorption.
Because the metabolic process is mainly carried out in the cytoplasm, in order to reduce the excessive energy consumption of redox intermediate products in transmembrane transportation, the researchers modified the gold nanoclusters by cysteine and injected it into hot vinegar In the cytoplasm of Murella spp., Highly biocompatible gold nanoclusters can get along with them for a long time in the body of Murella vinegar, which not only does not reduce its activity, but also greatly improves the quantum utilization efficiency of light. The engineered bacteria injected into the gold nanoclusters are placed in a specific culture solution, maintaining a pure CO 2 anaerobic atmosphere, and giving a certain intensity of light. Everything is ready, and a good show is really a start.
a) Flow chart of M. thermoacetica / gold nanocluster hybrid system; b) Schematic diagram of the work of M. thermoacetica bacteria (Photo source: Nat Nanotechnol. 2018, 13, 900-905)
The photons in the visible light enter the gold nanoclusters in the cytoplasm of M. thermoaceticum by irradiating them, and excite them to generate an electron ( < span class = "text-remarks" label = "Remarks"> e – ) and an empty Acupoint (h + ) , in order to prevent the generated electrons and holes from recombining, the cysteine wrapped around the gold nanoclusters (Cys) plays a role, cysteine is oxidized by holes to generate cystine (CySS) , in this process, the holes in the gold nanoclusters are successfully consumed. The excited electrons and absorbed CO2 meet in a class of enzyme intermediates, via the acetyl-CoA pathway < span class = "text-remarks" label = "Remarks"> (The Wood-Ljungdahl path mainly exists in anaerobic bacteria and archaebacteria, relying on CO / CO 2 and H 2 Carbon and energy sources for anabolic and catabolism) , successfully synthesize acetic acid molecular products, release them into the culture medium, and be collected and used.
Acetyl-CoA Pathway Artificial Photosynthesis Reaction Process
Study on the artificial photosynthesis synthesis of acetic acid is not only because of its simple structure, but the original intention of studying this synthesis process is because of important application of acetic acid in the chemical industry . For example, using acetic acid as the raw material, we can produce butanol. Butanol is known as a new fuel that can replace petroleum in the future because of its low saturated vapor pressure. It is also known as a new fuel that can replace petroleum in the future; Polymerization synthesizes polymer materials and synthesizes chiral molecules such as artemisinin and other pharmaceutical intermediates. These will be essential chemicals for our future survival on Mars.
Looking forward: future migrants in outer space
inAfter we successfully open the Pandora’s box of synthetic photosynthetic chemicals, more chemicals will be continuously synthesized in the future. For example, there is still 4% nitrogen on Mars. If a new artificial photosynthesis integrated system is developed in the future to synthesize nitrogen into ammonia compounds, it will provide immigrant Mars with ample fertilizer for the cultivation of crops.
greenhouse vegetable cultivation in the film (Source: “Mars Rescue”)
Otherwise, when immigrating to Mars in the future, I am afraid that we can only use the flavored organic fertilizer to grow fruits and vegetables like the male host in “Mars Rescue” …
References:
[1] Peidong Yang, et.al. Bacteria photosensitized by intracellular gold nanoclusters for solar fuel production. Nat Nanotechnol. 2018, 13, 900-905. < / p>
[2] Peidong Yang, et.al. Close-Packed nanowire-bacteria hybrids for efficient solar-driven CO2 fixation. Joule. 2020, 4, 1-12.
[3] Gengfeng Zheng, et.al. Efficientsolar-driven electrocatalytic CO2 reduction in aredox-medium-assisted system. Nat Commun. 2018, 9, 5003.
This article comes from the WeChat public account: Institute of Science (ID: kexuedayuan) , Author: Li Qinglin (Qingdao Institute of Bioenergy and Bioprocess Technology)