High-purity carbon monoxide production via photothermal formic acid decomposition over fluorite ZrO2

High-purity carbon monoxide (CO), crucial for various high-tech industries, requires complex purification and further energy input. Here we show that pure fluorite ZrO2 can produce clean CO without purification by driving formic acid dehydration and completely shutting off the formic acid dehydrogenation pathway. An explosion method is developed for synthesizing pristine fluorite ZrO2 nanosheets that achieve a pure CO production rate of 55 mmol g−1 h−1 at 250 °C. Integrated with a homemade photothermal reactor, the fluorite ZrO2 nanosheets show a pure CO productivity of 83 mmol g−1 h−1 under 0.5 sun irradiation and a photochemical energy conversion efficiency of 12.3%. Moreover, this system generates over 1,538 l m−2 of pure CO per day under outdoor sunlight irradiation. This work charts a promising course for purification-free pure CO generation without secondary energy input. Obtaining high-purity CO requires energy-intensive purification processes. Here metastable fluorite ZrO2 is prepared that can catalyse thermal and photothermal formic acid dehydration to CO while completely shutting off the impurity-generating dehydrogenation pathway.