Direct Air Capture (DAC), a groundbreaking concept in the realm of climate solutions, has emerged as a pivotal avenue for achieving negative emissions. By directly extracting CO₂ from ambient air, DAC offers a unique advantage by addressing the root cause of increasing atmospheric CO₂ levels. Among DAC methodologies, the adsorption-desorption process utilizing solid adsorbents presents notable promise. However, the large heat of adsorption requires high energy consumption for regeneration of adsorbents, significantly compromising the economic viability and productivity of DAC. 

Here, we show a vapor promoted DAC process to recover the adsorbed CO₂ by in situ vapor purge using water harvested from atmosphere synergistically. The desorption of CO₂ is substantially enhanced in the presence of concentrated water vapors at around 100 °C, resulting in the concurrent production of 97.7% purity CO₂ and fresh water without the use of vacuum pumps. Moreover, we demonstrate a prototype of this DAC powered by sunlight, which recovers 98% of the adsorbed CO₂, the highest among all other DAC technologies, and consumes 20% less thermal energy. 

In another case when 10 kPa vacuum is applied, this in situ vapor purge can achieve near complete regeneration of the chemisorbents at temperatures as low as 60 °C, producing 99% purity CO₂ with a stable working capacity of 1.10-1.13 mmol/g for 45 cycles. The minimum work required for regeneration was only 1.62 MJ/kgCO₂, over 37% lower than temperature-vacuum swing desorption. This low-temperature regeneration process not only reduces the energy demand but also reduces the overall cost of DAC.