Capture energy to split carbon dioxide's extremely stable bonds. Sunlight, combined with a powerful system of mirrors, is one way to create the intense energy needed to split CO2 bonds. Many scientists working to split CO2 use the sun's light as an energy source — popular because light, captured during photosynthesis, is the way plants break down CO2. Sunlight can be captured and converted to energy using a semiconductor, like one gallium-phosphide semiconductor, which has bands of energy to capture and condense electrons and create electrical energy potential.
Use semiconductors to convert energy to electricity, to split CO2 bonds. Semiconductors convert optical energy to electrical energy, then deploy it to catalysts which split the bonds.
Keep the resultant molecules separated. One form of CO2-splitting — a machine called the CR5, which uses concentrated sunlight to split CO2 — produces CO or hydrogen, and oxygen. If not kept separate, they will recombine and create carbon dioxide and hydrogen. Gases and pressure are used to keep the elements separated.