Facile and Scalable Synthesis of Self-Supported Zn-Doped CuO Nanosheet Arrays for Efficient Nitrate Reduction to Ammonium
Zhuzhu Du, Kai Yang, Hongfang Du, Boxin Li, Ke Wang, Song He, Tingfeng Wang, Wei Ai
Abstract
CuO has been regarded as a promising catalyst for the electrochemical reduction of nitrate (NO 3 – RR) to ammonium (NH 3 ); however, the intrinsic activity is greatly restricted by its poor electrical property. In this work, self-supported Zn-doped CuO nanosheet arrays (Zn–CuO NAs) are synthesized for NO 3 – RR, where the Zn dopant regulates the electronic structure of CuO to significantly accelerate the interfacial charge transfer and inner electron transport kinetics. The Zn–CuO NAs are constructed by a one-step etching of commercial brass (Cu 64 Zn 36 alloy) in 0.1 M NaOH solution, which experiences a corrosion–oxidation–reconstruction process. Initially, the brass undergoes a dealloying procedure to produce nanosized Cu, which is immediately oxidized to the Cu 2 O unit with a low valence state. Subsequently, Cu 2 O is further oxidized to the CuO unit and reconstructed into nanosheets with the coprecipitation of Zn 2+ . For NO 3 – RR, Zn–CuO NAs show a high NH 3 production rate of 945.1 μg h –1 cm –2 and a Faradaic efficiency of up to 95.6% at −0.7 V in 0.1 M Na 2 SO 4 electrolyte with 0.01 M NaNO 3, which outperforms the majority of the state-of-the-art catalysts. The present work offers a facile yet very efficient strategy for the scale-up synthesis of Zn–CuO NAs for high-performance NH 3 production from NO 3 – RR.