Electrocatalytic Reduction of NO<sub>3</sub><sup>–</sup> to Ultrapure Ammonia on {200} Facet Dominant Cu Nanodendrites with High Conversion Faradaic Efficiency
Shivaraj B. Patil, Ting‐Ran Liu, Hung‐Lung Chou, Yubin Huang, Chia‐Che Chang, Yi‐Chia Chen, Ying‐Sheng Lin, Hsin Li, Yi‐Cheng Lee, Yuan Jay Chang, Ying‐Huang Lai, Cheng‐Yen Wen, Di‐Yan Wang
Abstract
Nitrate (NO3–) reduction reaction (NtRR) is considered as a green alternative method for the conventional method of NH3 synthesis (Haber–Bosch process), which is known as a high energy consuming and large CO2 emitting process. Herein, the copper nanodendrites (Cu NDs) grown along with the {200} facet as an efficient NtRR catalyst have been successfully fabricated and investigated. It exhibited high Faradaic efficiency of 97% at low potential (−0.3 V vs RHE). Furthermore, the 15NO3– isotope labeling method was utilized to confirm the formation of NH3. Both experimental and theoretical studies showed that NtRR on the Cu metal nanostructure is a facet dependent process. Dissociation of NO bonding is supposed to be the rate-determining step as NtRR is a spontaneously reductive and protonation process for all the different facets of Cu. Density functional theory (DFT) calculations revealed that Cu{200} and Cu{220} offer lower activation energy for dissociation of NO compared to that of Cu{111}.