Relevant parts:
"They used perovskite light-absorbers and either platinum or cobalt catalysts for the reaction. The platinum catalyst splits water into oxygen and hydrogen in the presence of sunlight, while cobalt triggers the reduction of carbon dioxide and water into syngas."
"The team replaced the thick glass substrates they had used before with thin conductive plastic substrates. They coated these with few-micrometers-thick layers each of perovskites, conductive metal-oxide and polymer layers, and cobalt or platinum catalyst."
"It produced hydrogen and carbon monoxide with efficiencies of about 0.6 percent and 0.05 percent respectively for each gram. That is low, but comparable to natural photosynthesis, which has a typical efficiency of 0.5 to 1 percent"
