Cambridge researchers have designed a new reactor capable of turning carbon dioxide, water and plastics into synthesis gas. The system uses a photoelectrochemical device powered by an encapsulated tricationic perovskite-based photocathode and an alloy anode.
The system uses a photoelectrochemical (PEC) device powered by an encapsulated tricationic perovskite-based photocathode and an alloy anode. The PEC system initially collects carbon dioxide2 from compressed CO2 flow, simulated post-combustion flue gas and atmospheric air. It then converts this CO2 into synthesis gas, carbon monoxide (CO) and hydrogen (H2).
“The process works by combining CO2-reduction into fuel by oxidizing the waste plastic-derived ethylene glycol (EG) into glycolic acid (GA), which can be used in the pharmaceutical, food and textile industries,” the researchers explained, noting that seosanode is used to catalyze the oxidation of EG. “Captured CO2 reduction enables the immobilized molecule cophthalocyanine catalyst at the photocathode.”
The research team explained that the process works in conjunction with the selective oxidation of pre-treated polyethylene terephthalate (PET) waste plastics and also converts them into fuel chemicals. It argued that this is an essential part of the system because the plastic donates electrons to the CO2. “The plastic breaks down into glycolic acid, which is widely used in the cosmetics industry, and CO2 converted into syngas, which is a simple fuel,” it stated.
The team also said that the system can work properly with a single visible light absorber without any external voltage. The open circuit voltage of the photovoltaic device is 1.1 V and it can absorb the 360-750 nm solar spectrum. “Replacing the thermodynamically challenging water oxidation with EG oxidation is necessary for the system to operate on a single light suppressor without an external voltage, while allowing waste PET recycling,” it stressed.
The researchers are currently developing a benchtop model and said they are considering using solar cells with a higher open-circuit voltage. They also hope to tune in against oxidation and control the oxidation of other biomass, textile or chemical waste products.
The system is presented in the study “Integrated capture of CO and solar-powered utilization2 of flue gases and air”, published in Joule. “With enough improvement, this solar powered proof of concept2 capture and drive system could be promising for future distributed off-grid scalable solar fuel and chemical synthesis technologies,” the researchers concluded.
