High-entropy FeCoNiCuRu solid solutions triggered cocktail effect to achieve fine-tuning adsorption energy for boosting nitrate electroreduction to ammonia

Abstract

Designing multi-site high-entropy alloys (HEAs) electrocatalysts with fine-tuning adsorption energy range for efficient NO3RR is crucial, but selecting metal elements and clarifying the “cocktail effect” mechanism for NO3RR using HEA solid solutions’ designability remains a challenge. Here, we synthesize FeCoNiCuRu high-entropy alloy (denoted as FeCoNiCuRu HEA) solid solutions as a NO3RR catalyst via a facile one-step solvothermal method. The FeCoNiCuRu HEA catalyst exhibits outstanding NO3RR performance with a maximum NH3 yield rate of 8414.5 μg h−1 cm−2 and a superior Faradaic efficiency of 94.5 %. Significantly, when evaluated in the flow cell, FeCoNiCuRu HEA displays an average Faradaic efficiency of up to 94.5 % and remarkable durability over 45 h. In situ ATR-FTIR, Raman spectroscopy and DFT calculations offer an intensive understanding of the activities of the different metal reaction sites, indicating that the synergistic “cocktail effect” of HEA effectively overcome the high-energy barriers to initial adsorption, enhance adsorption of *H, and suppressed competing HERs, thus facilitating the generation of NH3. This work not only promotes the understanding of the “cocktail effect” of NO3RR performance in the HEA system, but also guides the design/fabrication of advanced HEA electrocatalysts.