Pd Nanoparticle Size‐Dependent H<sup>*</sup> Coverage for Cu‐Catalyzed Nitrate Electro‐Reduction to Ammonia in Neutral Electrolyte
Hongbo Zhu, Jiacheng Jayden Wang, Jiacheng Jayden Wang, Zian Xu, Yongwen Tan, Jiacheng Wang, Jiacheng Wang
Abstract
Abstract Electrochemical conversion of nitrate (NO 3 − ) to ammonia (NH 3 ) is an effective approach to reduce nitrate pollutants in the environment and also a promising low‐temperature, low‐pressure method for ammonia synthesis. However, adequate H * intermediates are highly expected for NO 3 − hydrogenation, while suppressing competitive hydrogen evolution. Herein, the effect of H * coverage on the NO 3 RR for ammonia synthesis by Cu electrocatalysts is investigated. The H * coverage can be adjusted by changing Pd nanoparticle sizes. The optimized Pd@Cu with an average Pd size of 2.88 nm shows the best activity for NO 3 RR, achieving a maximum Faradaic efficiency of 97% (at −0.8 V vs RHE) and an NH 3 yield of 21 mg h −1 cm − 2 , from an industrial wastewater level of 500 ppm NO 3 – . In situ electrochemical experiments indicate that Pd particles with 2.88 nm can promote NO 3 − hydrogenation to NH 3 via well‐modulated coverage of adsorbed H * species. Coupling the anodic glycerol oxidation reaction, ammonium and formate are successfully obtained as value‐added products in a membrane electrode assembly electrolyzer. This work provides a feasible strategy for obtaining size‐dependent H * intermediates for hydrogenation.