Triazine-Functionalized Cellulose Fibers as Electrocatalysts for Nitrate-to-Ammonia Conversion

Triazine-functionalized cellulose fibers (TCFs) have been synthesized by reacting cellulose with epichlorohydrin and thiocyanuric acid in DMSO solvent by a conventional method. The resultant cellulosic material shows the presence of N (2.43 wt %) and S (3.1 wt %), indicating the incorporation of thiocyanuric acid moieties. The functionalization and structure of TCF have been established by state-of-the-art analytical techniques. TCF is employed as a metal-free electrocatalyst in the electrochemical nitrate reduction reaction (eNO 3 RR) for ammonia synthesis. The electrocatalyst demonstrated a reasonable NH 3 yield rate of 29 μg h –1 mg cat –1 (1.7 mmol h –1 g cat –1 ) with 33.5% Faradaic efficiency (FE) at −0.9 V vs RHE. A consistent eNO 3 RR activity is demonstrated by TCF over 5 consecutive cycles, while sustained catalytic performance and structural integrity are confirmed through a 20 h chronoamperometric study. Interestingly, TCF exhibited eNO 3 RR activity in simulated wastewater at a 100-fold higher nitrate concentration, yielding 2.7 μg h –1 mg cat –1 (0.15 mmol h –1 g cat –1 ) of ammonia with a FE of 13.9% at −0.9 V vs RHE. These findings highlight measurable catalytic performance under elevated nitrate conditions, emphasizing selectivity and optimization potential for practical recovery. In situ Raman spectroscopy analysis identified the *NH 3 and *NO 2 species, confirming the formation of intermediates during nitrate reduction.