Polyoxometalate Confined Synthesis of BiVO₄ Nanocluster for Urea Production with Remarkable O₂/N₂ Tolerance

Urea electrosynthesis from flue gas and NO₃ ^- under operating conditions represents a promising alternative technology to traditional energy-intensive industrial process. Herein, we explore a polyoxometalate confined synthesis strategy to prepare ultrafine BiVO₄ nanocluster by pre-incorporating [V₁₀O₂₈]^6- into NH₂-MIL-101-Al (MIL) framework. The resulting BiVO₄@MIL-n can efficiently drive co-reduction of NO₃ ^- and CO₂ to urea. A record urea yield of 63.4 mmol h^-1 g_cat ^-1 was achieved under CO₂/O₂ mixed gases (33 % O₂) atmosphere, and comparable performance can be obtained by feeding flue gas, demonstrating remarkable O₂/N₂ tolerance and potential feasibility for urea production under operating conditions. Systematic investigations revealed that MIL carrier with -NH₂ group can enrich CO₂, and BiVO₄ nanocluster can reduce both NO₃ ^- and CO₂ to ensure efficient urea synthesis even in the presence of O₂. This work demonstrates the key role of in situ growth of BiVO₄ nanocluster within a NH₂-framework in facilitating urea electrosynthesis with exceptional tolerance to O₂/N₂.