Active sites-rich layered double hydroxide for nitrate-to-ammonia production with high selectivity and stability

Energy-efficient electrochemical ammonia production from dilute nitrate solution

“…It supports the claim that the half-cell energy efficiency of the Ni 3 Fe–CO 3 LDH/Cu foam is superior to those of other recent electrocatalysts both at high and low NO 3 − concentrations, achieving 36.6% and 36.2% at 5 mM and 10 mM NO 3 − concentration respectively. 5,10,13–16,18,20,23,24,39,43–48…”

“…This compares favourably to electrodes that utilise nickel foam or carbon based substrates (carbon paper, carbon cloth) that only act as electrical conductors. 10,13–16,18,23,24,43–45,47,48,53 As a hydrogen radical supplier, layered double hydroxides (LDH; ) could be a unique catalyst platform because of its high overpotential for HER if the Heyrovsky step (H ads * + H 2 O + e − → H 2 + OH) would be suppressed and if the Volmer step (H 2 O + e − → H ads * + OH − ) would be activated. Very few articles have been reported on electrochemical NitRR using an LDH because high voltage should require to drive the cathodic reaction in order to overcome the low inherent electrical conductivity.…”

“…To date, few LDHs have been used as active materials in electrochemical NitRR, in each case both a high voltage and high nitrate concentration were needed to achieve a high FE which decreases the overall energy efficiency ( i.e. [NO 3 − ] = 14 mM [NO 3 − ] for Co 1 Fe–CO 3 LDH; 43 [NO 3 − ] = 25 mM for Cu 2 CoAl–CO 3 LDH; 52 [NO 3 − ] = 100 mM for Co 3 AlCO 3 LDH 53 ). In this work, we have explored a range of designer LDH decorated Cu foam electrodes (LDH/Cu foam) in order to investigate the role of mixed transition metal combinations to generate hydrogen radicals.…”

“…This compares favourably to electrodes that utilise nickel foam or carbon based substrates (carbon paper, carbon cloth) that only act as electrical conductors. 10,[13][14][15][16]18,23,24,[43][44][45]47,48,53 As a hydrogen radical supplier, layered double hydroxides (LDH; . Over 1 h the system exhibited a NH 3 productivity of 1.261 mg cm À2 h À1 and a 96.8% FE at À0.2 V. This equates to a 36.6% half-cell energy efficiency.…”

“…This compares favourably to electrodes that utilise nickel foam or carbon based substrates (carbon paper, carbon cloth) that only act as electrical conductors. 10,[13][14][15][16]18,23,24,[43][44][45]47,48,53 As a hydrogen radical supplier, layered double hydroxides (LDH; We found that the Ni 3 Fe-CO 3 LDH/Cu foam electrode achieved the best electrochemical NitRR producing a 95.8% NH 3 selectivity with a 98.5% NO 3 À conversion in 5 mM NO 3…”