Modulating the electronic structure of CuxNy@TiO2 via nitrogen doping for efficient PH3 removal from the circle off-gas used in polysilicon production

Conventional adsorbents used for removal of trace phosphine from recycled off-gas in polysilicon production often suffer from limited breakthrough capacity and rapid deactivation under oxygen-free conditions. In this work, a nitrogen-doped TiO 2 -supported Cu-based adsorbent (Cu x N y @TiO 2 ) was synthesized using a simple one-pot solid-state route to enhance PH 3 removal performance. Nitrogen incorporation effectively regulates the surface chemical and electronic properties of TiO 2 , resulting in improved dispersion and stabilization of CuO species, enhanced surface basicity, and increased abundance of reactive surface oxygen species. Under an inert N 2 atmosphere at 30 °C, the optimized Cu 20 N 10 @TiO 2 exhibited a high PH 3 breakthrough capacity of 204.7 mg·g −1 and a breakthrough time of 2280 min at a weight hourly space velocity of 24,000 h −1 , significantly outperforming the undoped counterpart. Density functional theory calculations revealed that PH 3 could be readily activated on CuO surfaces through a low-energy stepwise dehydrogenation pathway, facilitating subsequent oxidation by lattice and chemisorbed oxygen species. Regeneration experiments demonstrated that the adsorbent retained 86.6% of its initial capacity after three cycles. This study proposes a cost-effective strategy for designing robust Cu-based adsorbents and offers mechanistic insights into adsorption-oxidation processes relevant to industrial gas purification.