PV-Trombe wall integrated with PEI-MIL-101(Cr) for power, indoor air dehumidification and carbon dioxide removal: Materials, coupled adsorption kinetics and system performance evaluation

Indoor CO2 and humidity control in airtight buildings relies on energy-intensive HVAC, driving the need for low-energy alternatives. Amine-functionalized MOFs exhibit significant potential for applications in synergistic CO2–H2O adsorption and low-energy indoor air regulation. Here, a PV-Trombe wall integrated with PEI-MIL-101(Cr) is proposed for solar-driven power generation, thermal regulation, dehumidification, and CO2 removal. Firstly, adsorbents with varying PEI loadings were synthesized and characterized, and their H2O/CO2 co-adsorption behavior was systematically investigated. Secondly, a coupled heat–mass transfer model was developed and validated. Thirdly, the system was applied under typical climatic conditions in Nanjing to investigate its performance in electricity generation, thermal regulation, dehumidification, and CO2 removal. The main conclusions are as follows: (1) 30% PEI-MIL-101 (Cr) exhibited optimal performance, achieving 0.82 g/g H2O and 0.081 g/g CO2 uptake at 25 °C and 70% RH, enabling synergistic dehumidification–carbon capture. (2) Water vapor exhibits a dual effect on CO2 adsorption: at moderate humidity, it enhances uptake through bicarbonate formation; however, at high humidity, it inhibits adsorption due to pore blocking and diffusion resistance. (3) The material shows moderate adsorption heat, enabling regeneration at 70 °C, and maintains stable capacity over 10 cycles. (4) The constructed PV-Trombe wall realizes the coordinated operation of power generation, thermal regulation, and adsorption regeneration: in summer, the system reduces the photovoltaic temperature by 5-9 °C, the photoelectric efficiency is 15%-19%, and achieves H2O adsorption of 0.35 g/g and CO2 adsorption of 0.015 g/g. This work offers a low-energy, solar-driven solution for synergistic CO2 and humidity control in buildings.