Boosting Nitrogen Activation via Ag Nanoneedle Arrays for Efficient Ammonia Synthesis

Abstract

Electrocatalytic N 2 reduction reaction (eNRR) provides a promising carbonneutral and sustainable ammonia-synthesizing alternative to the Haber-Bosch process. However, the nonpolar N 2 has significant thermodynamic stability and requires ultrahigh energy to break down the N�N bond. Here, we report the construction of local enhanced electric fields (LEEFs) by Ag nanoneedle arrays to promote N�N fracture thus assisting the eNRR. The LEEFs could induce charge polarization on nitrogen atoms and reduce the energy barrier in the N 2 first-protonation step. The detected N�N and N�H intermediates prove the cleavage of the N�N bond and the hydrogenation of N 2 by LEEFs. The increased LEEFs lead to logarithmic growth rates for the targeted eNRR and exponential growth rates for the unavoidable competitive hydrogen evolution reaction. Thus, regulation and tuning of LEEFs to ∼4 × 10 4 kV m −1 endows the raise of eNRR to the summit, achieving high ammonia selectivity with a Faradaic efficiency of 72.3 ± 4.0%.

Manipulating Coupled Field Enhancement in Slot-under-Groove Nanoarrays for Universal Surface-Enhanced Raman Scattering

“…Meanwhile, the RSDs from the unimprinted AAO samples are calculated to be 27.58% and 32.03%, respectively, and are approximately four times higher than those from the I-AAO samples (Figure S21). Therefore, compared to the previous studies, − the slot-under-groove nanoarrays demonstrate an obvious advantage as SERS substrates to achieve good signal reproducibility. Moreover, the recyclability is revealed by peeling off the slot-under-groove nanoarrays from the same I-AAO template, where the structural profile and SERS performance of the slot-under-groove nanoarrays are still comparable to the initial status after at least three repetitions (Figure S22).…”

Accelerating Industrial‐Level NO3− Electroreduction to Ammonia on Cu Grain Boundary Sites via Heteroatom Doping Strategy

“…As shown in Figure S35c, Supporting Information, the values of R NO3‐RR −1 , a difference value between R NO3‐RR −1 + R HER −1 and R HER −1 , varied significantly from the different electrodes, indicating the different reaction rates between NO 3 − RR and HER. [ 26 ] The Sn 1% ‐Cu electrode showed a maximum difference value of 0.043, demonstrating that it possessed the fastest NO 3 − RR kinetics. The enhanced kinetics of Sn 1% ‐Cu electrode could be attributed to the highly exposed GBs active sites on surfaces.…”

Towards sustainable electrochemical ammonia synthesis

“…Pd-based catalysts have the higher FE of 40% but mild current density resulting in low NH 3 yield. 13 For some precious metals with poor HER performance, such as Ag and Au, 14,15 the FE of eNRR is up to 50-80%. Consequently, inhibiting HER on noble metal surfaces is one of the major challenges for eNRR.…”