Context: Researchers have been working on a hybrid system that creates the building blocks for organic molecules by capturing the energy of sunlight. And this system works by combining bacteria and nanowires.

   Background 

• If humans ever hope to colonize Mars, the settlers will need to manufacture on-planet a huge range of organic compounds, from fuels to drugs, that are too expensive to ship from Earth.
• We can’t ship packages between Mars and Earth back on forth: one, that would be extremely expensive; two, it is not sustainable. So it is necessary for us to have a plan to produce most items locally.
• The only other requirement, besides sunlight, is water, which on Mars is relatively abundant in the polar ice caps and likely lies frozen underground over most of the planet?.

About Nanowires 

• They are incredibly thin silicon wires that are about a hundredth of the width of a human hair. 
• They are used as electronic components, sensors, and solar cells. In order to work it, we only need sunlight and water, which Mars has plenty on its vast surfaces in frozen form.

How does the system work? 

• The system works like photosynthesis.
• The left side of the reactor is the chamber which contains the nanowire-bacteria hybrid that reduces CO2 to form acetate. Oxygen is produced on the right side.
• The team first demonstrated the nanowire-bacteria hybrid reactor five years ago; however, the solar conversion efficiency was only about 0.4%. 
• The researchers tried to increase the efficiency by putting more bacteria onto the nanowires, however, that idea wouldn't make the cut.
• The efficiency of the system is comparable to the plant that best converts CO2 to sugar, which is sugar cane by 4-5% efficiency.
• Top efficiency is achieved by operating at the optimal acidity for bacteria, which gave more efficient conversion of solar energy to carbon bonds.  
• The silicon nanowires are essentially like an antenna: They capture the solar photon just like a solar panel. Within these silicon nanowires, they will generate electrons and feed them to these bacteria. Then the bacteria absorb CO2, and spit out acetate. 
• The biohybrid can also pull carbon dioxide from the air on Earth to make organic compounds and simultaneously address climate change, which is caused by an excess of human-produced CO2 in the atmosphere.
• We can almost think of this as planting new trees. While producing energy, it helps with climate change too. It brings a good deal for everyone involved.