The collection of recyclable ammonia (NH3) from electrocatalytically reduced nitrate (NO3RR) provides a sustainable strategy to end the ecological nitrogen cycle in an energy-saving and environmentally friendly way and avoid nitrification pollution. The emerging intermetallic single-atom alloys (iSAAs) obtain the highest single-atomic site density by separating adjacent metal atoms into single atoms stabilized by another metal in the intermetallic structure, which is expected to couple the catalytic benefits of intermetallic nanocrystals and single-atom catalysts to promote NO3RR.
Recently,Guihua Yu, University of Texas at AustinOur group reports an intermetallic single-atomic alloy In-PD bimetal (ISAA In-Pdene) with six atomic layers and a closed surface (111), which couples multiple advantages of intermetallic structure, single-atom catalyst, and metal to facilitate neutral NO3Rr for selective NH3 electrosynthesis.
For this catalyst, the P-region metal can induce a phase transition from face-centered cubic (FCC) PD to intermetallic body-centered cubic (BCC) PD-IN (PM3 M) for the separation of Pd atoms in In-Pdene. The experimental results show that the Isaa In-Pink catalyst has high NO3-NH3 performance, and the Faraday efficiency (Fe(NH3)) and yield of NH3 are 87., respectively2% and 2806 mg h-1 mgpd-1。At the same time, the catalyst also has excellent electrocatalytic stability. After more than 100 hours and 20 cycles of continuous electrolysis, the selectivity of catalytic activity increased.
Experimental results and theoretical calculations show that Isaa In-Dene has a two-dimensionally separated PD with coordination with IN atoms compared to FCC PDENE, proving that the downward shift of the PD-D state leads to a significant reduction in the energy band, and the electron density is significantly increased by the narrowed P-D hybridization between the In-P and PD-D states around the Fermi level, so it can adsorb NO3 more strongly and reduce the formation of the key reaction intermediate *NHO (rate-determining step) enhances the dynamics of NO3RR.
In addition, considering the excellent NO3RR activity and selectivity of the Isaa In-Pink catalyst, a Zn-NO3 flow cell with Isaa In-Padene as the negative electrode and Zn as the negative electrode was developed, and the flow cell had 1264 MW CM-2 power density and 934% Fe (NH3), as well as excellent electrochemical stability. In general, this work synthesized bimetalene with a small number of atomic layers and intermetallic BCC structure and studied its catalytic mechanism, which provides a new idea for the design of NO3RR catalysts.
intermetallic single-atom alloy in–pd bimetallene for neutral electrosynthesis of ammonia from nitrate. journal of the american chemical society, 2023. doi: 10.1021/jacs.3c03432