Au nanoparticles with oxygen vacancies on BiVO for electrocatalytic nitrate reduction to ammonia.

Ammonia (NH) is an important energy carrier and agricultural fertilizer. Development of electrocatalysts for efficient NH electrosynthesis the nitrate reduction reaction (NitRR) is highly desirable but remains a key challenge. In this work, we successfully loaded Au nanoparticles on BiVO by a one-step hydrothermal method. It is demonstrated that by using Au nanoparticles (10-15 nm) embedded on BiVO (Au/BiVO) with oxygen vacancies (Au loading is 1.3 wt%), the electrocatalytic NitRR is indeed possible under ambient conditions. Unexpectedly, at -1.35 V ( RHE), the yield rate for NH of Au/BiVO reached 3320.9 ± 89.9 μg h cm, which was far superior to (11.3 μg h cm) pristine BiVO. The N isotope labeling experiments confirmed that the produced NH indeed originated from the nitrate reduction reaction catalyzed by Au/BiVO. The comprehensive analysis further confirms that the oxygen vacancies in Au/BiVO can effectively weaken the N-O bonding and restrain the formation of by-products, resulting in high faradaic efficiency and NH selectivity. Furthermore, differential electrochemical mass spectrometry (DEMS) was adopted to monitor the electrochemical separation of the NitRR products on the surface of Au/BiVO.