Engineering of Bimetallic Cu–Pt Nanostructures for the Electrochemical Ammonia Synthesis via Nitrate Reduction
Deepak K. K. Kori, Apurba K. Das
Abstract
The electrochemical nitrate reduction reaction (NO 3 RR) is an environmentally friendly and low carbon emission method that is attractive for producing high-value added NH 3 . However, NO 3 RR experiences poor selectivity and slow kinetics because of its complex reaction intermediates and the complicated process of eight electron transfer. Herein, the Cu-rich bimetallic nanocomposite CuPt on nanofibrillar networks of peptide bolaamphiphile hydrogels is reported as a high-performance NO 3 RR electrocatalyst for the conversion of NO 3 – to NH 3 at ambient temperature. The CuPt(3:1)@hydrogel in comparison with the CuPt(1:1)@hydrogel and CuPt(1:3)@hydrogel displays exceptional catalytic performance with a maximum Faradaic efficiency of 72.33% at −0.1 V (vs RHE) and a relatively high NH 3 yield of 0.71 mg h –1 mg cat –1 at −0.3 V (vs RHE) in alkaline electrolyte (1 M KOH) containing 100 mM KNO 3 . The nanofibrillar networks of peptide bolaamphiphiles provide high catalytic active sites and increase proton transfer kinetics, which results in the enhancement of NO 3 RR performance. The control experiments support that the produced NH 3 originated from NO 3 – reduction rather than any impurities. The durability tests suggest that the CuPt(3:1)@hydrogel maintains excellent morphological and structural stability after long-term electroreduction. The as-synthesized CuPt nanostructures were characterized by FE-SEM, EDS, HR-TEM, XRD, rheology, and XPS analyses. The current strategy has the potential to create new opportunities for developing nanomaterials that are designed rationally for future electrocatalysts.