Chen Chen1, Xiaorong Zhu2, Xiaojian Wen3, Yangyang Zhou1, Ling Zhou1, Hao Li1, Li Tao1, Qiling Li1, Shiqian Du1, Tingting Liu1, Dafeng Yan1, Chao Xie1, Yuqin Zou1, Yanyong Wang1, Ru Chen1, Jia Huo1, Yafei Li4, Jun Cheng5, Hui Su6, Xu Zhao6, Weiren Cheng6, Qinghua Liu7, Hongzhen Lin8, Jun Luo9, Jun Chen10, Mingdong Dong11, Kai Cheng12, Conggang Li12, Shuangyin Wang13. 1. State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, P. R. China. 2. College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, P. R. China. 3. State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, P. R. China. 4. College of Chemistry and Materials Science, Nanjing Normal University, Nanjing, P. R. China. liyafei@njnu.edu.cn. 5. State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, P. R. China. chengjun@xmu.edu.cn. 6. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, P. R. China. 7. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, P. R. China. qhliu@ustc.edu.cn. 8. i-LAB, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, P. R. China. 9. Tianjin Key Laboratory of Advanced Functional Porous Materials and Center for Electron Microscopy, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin, P. R. China. 10. Intelligent Polymer Research Institute, Australian Institute of Innovative Materials, Innovation Campus, University of Wollongong, Wollongong, NSW, Australia. junc@uow.edu.au. 11. Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark. 12. Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan Collaborative Innovation Center of Chemistry for Life Sciences, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, P. R. China. 13. State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, P. R. China. shuangyinwang@hnu.edu.cn.
Abstract
The use of nitrogen fertilizers has been estimated to have supported 27% of the world's population over the past century. Urea (CO(NH2)2) is conventionally synthesized through two consecutive industrial processes, N2 + H2 → NH3 followed by NH3 + CO2 → urea. Both reactions operate under harsh conditions and consume more than 2% of the world's energy. Urea synthesis consumes approximately 80% of the NH3 produced globally. Here we directly coupled N2 and CO2 in H2O to produce urea under ambient conditions. The process was carried out using an electrocatalyst consisting of PdCu alloy nanoparticles on TiO2 nanosheets. This coupling reaction occurs through the formation of C-N bonds via the thermodynamically spontaneous reaction between *N=N* and CO. Products were identified and quantified using isotope labelling and the mechanism investigated using isotope-labelled operando synchrotron-radiation Fourier transform infrared spectroscopy. A high rate of urea formation of 3.36 mmol g-1 h-1 and corresponding Faradic efficiency of 8.92% were measured at -0.4 V versus reversible hydrogen electrode.
The use of nitrogen fertilizers has been estimated to have supported 27% of the world's population over the past century. n class="Chemical">Urea (CO(NH2)2) is conventionally synthesized through two consecutive industrial processes, N2 + H2 → NH3 followed by NH3 + CO2 → urea. Both reactions operate under harsh conditions and consume more than 2% of the world's energy. Urea synthesis consumes approximately 80% of the NH3 produced globally. Here we directly coupled N2 and CO2 in H2O to produce urea under ambient conditions. The process was carried out using an electrocatalyst consisting of PdCu alloy nanoparticles on TiO2 nanosheets. This coupling reaction occurs through the formation of C-N bonds via the thermodynamically spontaneous reaction between *N=N* and CO. Products were identified and quantified using isotope labelling and the mechanism investigated using isotope-labelled operando synchrotron-radiation Fourier transform infrared spectroscopy. A high rate of urea formation of 3.36 mmol g-1 h-1 and corresponding Faradic efficiency of 8.92% were measured at -0.4 V versus reversible hydrogen electrode.