Electroreduction of NO₃⁻on tubular porous Ti electrodes

Abstract

Non-efficient fertilizer use in agriculture causes nitrate runoff, polluting rivers and streams. This pollution can be mitigated by partially converting nitrate into ammonia – rebalancing the composition to ammonium nitrate,...

Cu2O–Cu@Titanium Surface with Synergistic Performance for Nitrate-to-Ammonia Electrochemical Reduction

“…However, a sustained increment can be seen in the current density at alkaline conditions from −0.4 V toward more negative potentials. A different behavior is observed under acidic conditions, where HER is highly suppressed by the high availability of NO 3 – ions that compete for the active sites with protons, conducting the reaction toward NH 3 . In the case of the alkaline electrolyte, HER seems to be limited by the low proton concentrations in the electrolyte along with the high concentration of K + ions in solution.…”

“…A different behavior is observed under acidic conditions, where HER is highly suppressed by the high availability of NO 3 − ions that compete for the active sites with protons, conducting the reaction toward NH 3 . 39 In the case of the alkaline electrolyte, HER seems to be limited by the low proton concentrations in the electrolyte along with the high concentration of K + ions in solution. Monteiro et al have observed a reduction in activity of HER at a high concentration of weakly hydrate ions such K + in high alkaline solutions.…”

Emerging Applications, Developments, Prospects, and Challenges of Electrochemical Nitrate‐to‐Ammonia Conversion

“…Using tubular porous Ti electrodes, high faradaic efficiency of 58% and partial current density to NH 3 of −33 mA cm −2 at −1 V versus RHE were achieved. [ 24 ] Marta C. Hatzell et al. synthesized Pd nanocatalysts with controlled facets, and demonstrated the order of catalytic activity of different facets in alkaline as follows: Pd(111) > Pd(100) > Pd(hk0) for nitrate reduction, and Pd(100) > Pd(hk0) > Pd(111) for nitrite reduction.…”

“…Using tubular porous Ti electrodes, high faradaic efficiency of 58% and partial current density to NH 3 of −33 mA cm −2 at −1 V versus RHE were achieved. [24] -to-NH 3 conversion with the widest potential range below 0.06 V, and Rh (100) has the best activity and selectivity toward NH 3 at potential of −0.57 to 0.15 V. [25] Zhu et al used a self-templating method to synthesize Ir nanotubes under hydrothermal conditions. The Faraday efficiency of NH 3 was as high as 84.7% at 0.06 V versus RHE, with an NH 3 yield rate of 921 µg h −1 mg cat −1 , which is better than commercial Ir catalysts.…”

Recent developments in Ti-based nanocatalysts for electrochemical nitrate-to-ammonia conversion

“…However, the flow-through conditions take NO and N 2 O away from the solution, promote the homogeneous reaction of NO 2 − and NH 2 OH to NO and N 2 O, hinder the consecutive electrochemical reduction of NO 2 − and NH 2 OH towards NH 3 , and eventually result in a decrease of FE NH 3 . 37 Furthermore, Tarpeh et al constructed a representative flow-cell configuration with a polycrystalline titanium electrode for the NO 3 − RR and revealed that NO 2 − and NH 3 accounted for almost all NO 3 − RR products, the selectivity was flow rate dependent, and NH 3 was favored at the lowest flow rate. The above results suggested that the NO 3 − RR was subject to mass transport limitations.…”