Tungsten Nitride/Tungsten Oxide Nanosheets for Enhanced Oxynitride Intermediate Adsorption and Hydrogenation in Nitrate Electroreduction to Ammonia

作者：Zhencong Huang, Baopeng Yang, Yulong Zhou, Wuqing Luo, Gen Chen, Min Liu, Xiaohe Liu, Renzhi Ma, Ning Zhang · 发表于：ACS Nano · 年份：2023 · DOI：10.1021/acsnano.3c07734 · 被引用次数：92 · 研究领域：Ammonia Synthesis and Nitrogen Reduction、Advanced Photocatalysis Techniques、MXene and MAX Phase Materials

Electrochemical NO 3 – reduction reaction (NO 3 RR) is a promising technique for green NH 3 synthesis. Tungsten oxide (WO 3 ) has been regarded as an effective electrocatalyst for electrochemical NH 3 synthesis. However, the weak adsorption and the sluggish hydrogenation of oxynitride intermediates (NO x, e.g., *NO 3 and *NO 2 ) over WO 3 materials hinder the efficiency of converting NO 3 – to NH 3 . Herein, we design a heterostructure of tungsten nitride (WN) and WO 3 (WN/WO 3 ) nanosheets to optimize *NO 3 and *NO 2 adsorptions and facilitate *NO 2 hydrogenations to achieve a highly efficient electrochemical NO 3 RR to produce NH 3 . Theoretical calculations predict that locally introducing WN into WO 3 will shorten the distance between adjacent W atoms, resulting in *NO 3 and *NO 2 being strongly adsorbed on W active sites in the form of bidentate ligands instead of the relatively weak monodentate ligands. Furthermore, WN facilitates H 2 O dissociation to supply the requisite protons, which is beneficial for *NO 2 hydrogenations. Inspired by theoretical prediction, WN/WO 3 nanosheets are successfully fabricated through a high-temperature nitridation process. The transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption near-edge spectroscopy investigations confirm that the amorphous WN has been locally introduced in situ into WO 3 nanosheets to form a composite heterostructure. The as-prepared WN/WO 3 nanosheets exhibit a high Faraday efficie...