Au nanoclusters anchored on TiO2 nanosheets for high-efficiency electroreduction of nitrate to ammonia

Electrocatalytic nitrate reduction reaction (NO3RR) offers a unique rationale for green NH3 synthesis, yet the lack of highefficiency NO3RR catalysts remains a great challenge. In this work, we show that Au nanoclusters anchored on TiO2 nanosheets can efficiently catalyze the conversion of NO3RR-to-NH3 under ambient conditions, achieving a maximal Faradic efficiency of 91%, a peak yield rate of 1923 mu g center dot h(-1)center dot mg(cat).(-1), and high durability over 10 consecutive cycles, all of which are comparable to the recently reported metrics (including transition metal and noble metal-based catalysts) and exceed those of pristine TiO2. Moreover, a galvanic Zn-nitrate battery using the catalyst as the cathode was proposed, which shows a power density of 3.62 mW center dot cm(-2) and a yield rate of 452 mu g center dot h(-1)center dot mg(cat)(-1). Theoretical simulations further indicate that the atomically dispersed Au clusters can promote the adsorption and activation of NO3- species, and reduce the NO3RR-to-NH3 barrier, thus leading to an accelerated cathodic reaction. This work highlights the importance of metal clusters for the NH3 electrosynthesis and nitrate removal.

Automated summary

In this study, Au nanoclusters anchored on TiO2 nanosheets were found to efficiently catalyze the conversion of NO3RR-to-NH3 under ambient conditions, achieving a maximal Faradic efficiency of 91% and a peak yield rate of 1923 μg/h·mg(cat). Furthermore, a galvanic Zn-nitrate battery using the catalyst as the cathode demonstrated high power density and yield rate. Theoretical simulations indicated that the atomically dispersed Au clusters promoted the adsorption and activation of NO3- species, reducing the barrier for NO3RR-to-NH3 and accelerating the cathodic reaction.