Selective electrocatalytic synthesis of urea with nitrate and carbon dioxide

Abstract

Synthetic nitrogen (N) fertilizers, especially urea (CO(NH2)2) with the highest nitrogen content, nourish crop production to underpin human life. The conventional urea synthesis relies on harsh industrial processes, which consumes approximately 2% of annual global energy. Instead, electrocatalysis is an emerging sustainable technology to produce urea at ambient conditions. Herein, by directly coupling nitrate (NO3 − ) with carbon dioxide (CO2) on an indium hydroxide catalyst, we realize highly selective urea electro-synthesis at ambient conditions. We derive that CO2 can suppress adverse hydrogen evolution reaction by transforming the surface semiconducting behaviour of the model catalyst in our work.The key step of C-N coupling initiates at an early stage through the reaction of *NO2 with *CO2 intermediates owing to the low energy barrier on {100} facets, hence the subsequent urea is synthesized with high Faradaic efficiency, nitrogen selectivity, and carbon selectivity, which reach 53.4%, 82.9% and ~100%, respectively. This work offers a desirable urea synthesis route and provides deep insights into the fundamental origin of C-N coupling for guiding other sustainable synthesis of indispensable chemicals.

Sulfur Vacancy and Ti3C2Tx Cocatalyst Synergistically Boosting Interfacial Charge Transfer in 2D/2D Ti3C2Tx/ZnIn2S4 Heterostructure for Enhanced Photocatalytic Hydrogen Evolution

“…Similarly, the binding energy of In 3d 5/2 (444.90 eV) and In 3d 3/2 (452.45 eV) in N‐ZnIn 2 S 4 was also negatively shifted compared with that of In 3d 5/2 (444.98 eV) and In 3d 3/2 (452.53 eV) in F‐ZnIn 2 S 4 (Figure 4D). [ 52 ] In addition, the S 2p binding energy of S 2p 3/2 (161.54 eV) and S 2p 1/2 (162.75 eV) in N‐ZnIn 2 S 4 negatively shifted compared to that of S 2p 3/2 (161.61 eV) and S 2p 1/2 (162.82 eV) of F‐ZnIn 2 S 4 (Figure 4E). The negative shift of the binding energy of Zn 2p, In 3d, and S 2p can be attributed to the formation of S vacancies, which resulted in the reduction of coordination number of sulfur atoms and the decrease of the electron cloud density around them.…”

Emerging Electrochemical Processes to Decarbonize the Chemical Industry

“…A remarkable urea Faradaic efficiency of 53.4% can be achieved by substituting chemically inert N 2 with relatively active nitrate species using In(OH) 3 catalysts. 47 However, nitrate is usually made from ammonia oxidation, and the source of nitrate limits the application of this process. The products of the C–N coupling reaction are determined by the inherent property of electrocatalysts.…”

Synchrotron-radiation spectroscopic identification towards diverse local environments of single-atom catalysts

“…71,72 In addition, in situ/operando synchrotron-radiation Fourier-transform infrared spectroscopy (SR-FTIR) is performed to certify the phase transition and identify the active intermediates. 73 Experimental reports have demonstrated that SR-FTIR can show exponential signal intensication with respect to traditional FTIR. 74 In conclusion, it is certain that synchrotron-radiation spectral methods are powerful in the identication of local environments of SACs.…”