Steel slag as low-cost catalyst for artificial photosynthesis to convert CO₂ and water into hydrogen and methanol

Photoreduction of CO₂ with sunlight to produce solar fuels, also named artificial photosynthesis, is considered one of the most attractive strategies to face the challenge of reducing greenhouse gases and achieving climate neutrality. Following an approach in line with the principles of the circular economy, the low-cost catalytic system (1) based on an industrial by-product such as steel slag was assessed, which was properly modified with nanostructured palladium on its surface in order to make it capable of promoting the conversion of CO₂ into methanol and hydrogen through a two-stage process of photoreduction and thermal conversion having formic acid as the intermediate. Notably, for the first time in the literature steel slag is used as photoreduction catalyst.