Unveiling Electrochemical Urea Synthesis by Co‐Activation of CO₂ and N₂ with Mott–Schottky Heterostructure Catalysts

Abstract

Electrocatalytic C−N bond coupling to convert CO2 and N2 molecules into urea under ambient conditions is a promising alternative to harsh industrial processes. However, the adsorption and activation of inert gas molecules and then the driving of the C–N coupling reaction is energetically challenging. Herein, novel Mott–Schottky Bi‐BiVO4 heterostructures are described that realize a remarkable urea yield rate of 5.91 mmol h−1 g−1 and a Faradaic efficiency of 12.55 % at −0.4 V vs. RHE. Comprehensive analysis confirms the emerging space–charge region in the heterostructure interface not only facilitates the targeted adsorption and activation of CO2 and N2 molecules on the generated local nucleophilic and electrophilic regions, but also effectively suppresses CO poisoning and the formation of endothermic *NNH intermediates. This guarantees the desired exothermic coupling of *N=N* intermediates and generated CO to form the urea precursor, *NCON*.

Electrochemical C–N coupling with perovskite hybrids toward efficient urea synthesis

“…7c 7d and e, when the reduction of *NCON* follows the distal pathway, the required DG decreased to 0.54 eV compared to that of the alternating pathway (0.72 eV), suggesting that the BiFeO 3 /BiVO 4 hybrids were prone to pursue the distal mechanism until the release of urea molecules rather than the alternating pathway from the thermodynamic perspective. 31 The selectivity of the electrocatalytic urea production is closely associated with the formation of *NCON* intermediates. The possible N 2 reduction or the excessive release of CO would result in a decrease in the efficiency of the electrocatalytic C-N coupling reaction and further reduce the selectivity.…”

“…[23][24][25][26][27][28][29][30] Besides, the emerged electrochemical C-N coupling reaction may provide a new possibility of enhancing the spectrum of products of CO 2 by using CO 2 and amine derivatives/nitrogen sources (nitrate, nitrite, NO, and even N 2 ) as feedstock. 9,31,32 The desired product urea [CO(NH 2 ) 2 ] will be produced when the electrochemical C-N bond formation occurs by employing both N 2 and CO 2 as the feeding gas. 9 Urea is commonly utilized as the general feedstock in industry and the primary fertilizer for agriculture.…”

Electrocatalytic C–N Coupling for Urea Synthesis

“…[ 12 ] The strategy of catalyst design for urea synthesis should focus on the coadsorption and activation of gaseous molecules simultaneously. Yuan et al provided a strategy for coactivation and urea synthesis by heterostructure constructing, [ 18 ] as shown in Figure 4e. The electron‐rich N atom in nitrogen and electron‐deficient C atom in carbon dioxide would preferentially adsorb on the electrophilic and nucleophilic regions in Bi/BiVO 4 hybrids, attributed to the electronic interactions between the reactive molecules and hybrid structure (Figure 4f,g).…”

“…Yuan's work also displayed the feasibility of this reaction mechanism for urea synthesis on various electrocatalysts. [ 18,19 ]…”

Solar Urea: Towards a Sustainable Fertilizer Industry

“…Yuan et al. found a novel Mott‐Schottky Bi‐BiVO 4 heterostructures‐enabled urea synthesis from N 2 and CO 2 , with a Faradaic efficiency increased to 12.55 % [9] . However, to the best of our knowledge, no reports currently exist utilizing solar energy for urea synthesis to reduce the intensity of its operating conditions.…”