Electrocatalytic Reduction Of Nitrite Research Articles

A novel solar system for photothermal-assisted electrocatalytic nitrate reduction reaction to ammonia

The traditional Haber-Bosch process for ammonia synthesis is plagued by high energy consumption and significant CO2 emissions, leading to a noticeable environmental impact. As a promising solution, solar photovoltaic electrocatalytic synthesis of ammonia has garnered significant attention. This study designed an electrocatalytic nitrite reduction system for ammonia production that employs solar photothermal-assisted and investigate the effects of different photovoltaic power supply voltage, heating temperatures, and flow velocities. The results demonstrate. the maximum ammonia production performance was achieved at 1.3 V under normal temperature conditions, resulting in a maximum current density and ammonia production rate of 26 mA cm−2 and 1422.4 μg, respectively. Upon heating to 40 °C, the maximum average current density of the system is 40 mA cm−2, and ammonia production is 2293 μg, representing 53.8 % and 61.2 % increasing in comparison to ambient temperatures. Although elevating the temperature to 60 °C led to increased average current density and ammonia production, the system's stability decreased to certain extent. Cyclic electrolysis conducted at 1.1 V and 40 °C for an hour revealed that ammonia production is 553.2 μg, 957.8 μg, 714.6 μg for flow rates of 10 mL/min, 20 mL/min, and 40 mL/min, respectively. These findings provide a reliable reference for implementing solar energy as a power source in ammonia synthesis.

Single-atom Co alloyed Ru for electrocatalytic nitrite reduction to ammonia

Single-atom Co alloyed Ru for electrocatalytic nitrite reduction to ammonia

A Co3O4-x/Co nanocomposite with synergistically enhanced electrochemical activity for reduction of nitrite to ammonia

Electrocatalytic reduction of nitrite (NO2−) to ammonia (NH3) cannot only solve the problem of water pollution, but also produce high value-added ammonia. In practical applications, it is extremely important to develop high performance and cheap electrocatalysts. In this paper, a nano-electrocatalyst (Co3O4-x/Co) was prepared by combining cobalt trioxide (Co3O4-x) with cobalt nanoparticle (Co). The Co3O4-x is rich in oxygen vacancy. In neutral electrolyte, the composite electrocatalyst shows superior electrocatalytic activity for NO2− reduction to ammonia (Faraday efficiency up to 97 % at -0.8 V vs. RHE, ammonia yield up to 0.628 mmol h−1 cm−2 at -1.1 V vs. RHE). This performance may result from synergistic enhancement between Co3O4-x and Co.

Nb-doped NiO nanoflowers for nitrite electroreduction to ammonia

Electrocatalytic reduction of nitrite to ammonia (NO2RR) is considered as an appealing route to simultaneously achieve sustainable ammonia production and abate hazardous nitrite pollution. Herein, atomically Nb-doped NiO nanoflowers are designed as a high-performance NO2RR catalyst, which exhibits the highest NH3-Faradaic efficiency of 92.4% with an NH3 yield rate of 200.5μmol h-1cm-2 at -0.6V RHE. Theoretical calculations unravel that Nb dopants can act as Lewis acid sites to render effective NO2- activation, decreased protonation energy barriers, and restricted hydrogen evolution, ultimately leading to a high NO2RR selectivity and activity.

Mo single-atom catalyst boosts nitrite electroreduction for ammonia synthesis

Electrocatalytic nitrite reduction to ammonia (NO2RR) presents an efficient approach for both wastewater treatment and powerful ammonia electrosynthesis. However, the activity and selectivity of NO2RR are limited by its complex six−electron transfer process and competitive hydrogen evolution. Herein, Mo single atoms anchored on a zirconium dioxide substrate (Mo1–ZrO2) are first explored as a highly selective and active catalyst for the NO2RR, exhibiting a maximum NH3−Faraday efficiency of 94.83% with a corresponding ammonia yield rate of 346.92 μmol h−1 cm−2 at −0.7 V vs. RHE. Theoretical calculations reveal that the isolated Mo sites can effectively activate nitrite, enhance nitrite−to−ammonia protonation energetics and prohibit competitive hydrogen evolution, thus leading to the remarkably enhanced selectivity and activity of Mo1–ZrO2 for the NO2RR.

Cobalt-Nanoparticles-Decorated 3D Porous Nitrogen-Doped Carbon Network for Electrocatalytic Nitrite Reduction to Ammonia.

Electrocatalytic nitrite (NO2-) reduction offers the potential to synthesize high-value ammonia (NH3) while simultaneously removing NO2- pollution from aqueous solutions, but it requires high-efficiency catalysts to drive the complex six-electron reaction. Herein, cobalt-nanoparticle-decorated 3D porous nitrogen-doped carbon network (Co@NC) is proven as a high-efficiency catalyst for the selective electroreduction of NO2- to NH3. Such Co@NC attains a large NH3 yield of 922.7 μmol h-1 cm-2 and a high Faradaic efficiency of 95.4% under alkaline conditions. Furthermore, it shows remarkable electrochemical stability during cyclic electrolysis.

High-Performance Electrocatalytic Reduction of Nitrite to Ammonia under Ambient Conditions on a FeP@TiO2 Nanoribbon Array.

Electrochemical nitrite (NO2-) reduction is recognized as a promising strategy for synthesizing valuable ammonia (NH3) and degrading NO2- pollutants in wastewater. The six-electron process for the NO2- reduction reaction is complex and necessitates a highly selective and stable electrocatalyst for efficient conversion of NO2- to NH3. Herein, a FeP nanoparticle-decorated TiO2 nanoribbon array on a titanium plate (FeP@TiO2/TP) is proposed as an efficient catalyst for NH3 production under ambient conditions. In 0.1 M NaOH with 0.1 M NO2-, such a FeP@TiO2/TP affords a large NH3 yield of 346.6 μmol h-1 cm-2 and a high Faradaic efficiency of 97.1%. Additionally, it demonstrates excellent stability and durability during long-term cycling tests and electrolysis experiments.

Boosting electrocatalytic nitrite reduction to ammonia in neutral media by MoSe2 nanosheet with Se vacancies

Electrocatalytic reduction of nitrite (NO2−RR) is considered an effective method for removing harmful NO2− in wastewater while simultaneously generating high-value-added ammonia (NH3). This process, however, requires electrocatalysts with high activity and selectivity. Herein, a MoSe2 nanosheet array with Se vacancies supported on carbon cloth (MoSe2– x/CC)is proposed as a high-efficiency electrocatalyst for NO2− reduction to NH3. In 0.1 M phosphate-buffered saline with 0.1 M NO2−, MoSe2–x/CC exhibits an outstanding NH3 yield of 446.0 μmol h−1 cm−2 and a Faradaic efficiency of 96.9%, overpassing that of MoSe2/CC (278.1 μmol h−1 cm−2, 83.1%). Additionally, density functional theory calculations gain insights into reaction mechanism of MoSe2–x towards NO2−RR.

Elucidation of the Electrocatalytic Nitrite Reduction Mechanism by Bio-Inspired Copper Complexes.

Mononuclear copper complexes relevant to the active site of copper nitrite reductases (CuNiRs) are known to be catalytically active for the reduction of nitrite. Yet, their catalytic mechanism has thus far not been resolved. Here, we provide a complete description of the electrocatalytic nitrite reduction mechanism of a bio-inspired CuNiR catalyst Cu(tmpa) (tmpa = tris(2-pyridylmethyl)amine) in aqueous solution. Through a combination of electrochemical studies, reaction kinetics, and density functional theory (DFT) computations, we show that the protonation steps take place in a stepwise manner and are decoupled from electron transfer. The rate-determining step is a general acid-catalyzed protonation of a copper-ligated nitrous acid (HNO2) species. In view of the growing urge to convert nitrogen-containing compounds, this work provides principal reaction parameters for efficient electrochemical nitrite reduction. This contributes to the investigation and development of nitrite reduction catalysts, which is crucial to restore the biogeochemical nitrogen cycle.

High-efficiency electrocatalytic nitrite reduction toward ammonia synthesis on CoP@TiO2 nanoribbon array

Electrochemical reduction of nitrite (NO2-) can satisfy the necessity for NO2- contaminant removal and deliver a sustainable pathway for ammonia (NH3) generation. Its practical application yet requires highly efficient electrocatalysts to boost NH3 yield and Faradaic efficiency (FE). In this study, CoP nanoparticle-decorated TiO2 nanoribbon array on Ti plate (CoP@TiO2/TP) is verified as a high-efficiency electrocatalyst for the selective reduction of NO2- to NH3. When measured in 0.1M NaOH with NO2-, the freestanding CoP@TiO2/TP electrode delivers a large NH3 yield of 849.57μmol h-1 cm-2 and a high FE of 97.01% with good stability. Remarkably, the subsequently fabricated Zn-NO2- battery achieves a high power density of 1.24 mW cm-2 while delivering a NH3 yield of 714.40μg h-1 cm-2.

Defective PrOx for Efficient Electrochemical NO2−-to-NH3 in a Wide Potential Range

Electrocatalytic reduction of nitrite (NO2−) is a sustainable and carbon-neutral approach to producing green ammonia (NH3). We herein report the first work on building defects on PrOx for electrochemical NO2− reduction to NH3, and demonstrate a high NH3 yield of 2870 μg h−1 cm−2 at the optimal potential of –0.7 V with a faradaic efficiency (FE) of 97.6% and excellent FEs of >94% at a wide given potential range (−0.5 to −0.8 V). The kinetic isotope effect (KIE) study suggested that the reaction involved promoted hydrogenation. Theoretical calculations clarified that there was an accelerated rate-determining step of NO2− reduction on PrOx. The results also indicated that PrOx could be durable for long-term electrosynthesis and cycling tests.

Enhancing electro-reduction of nitrite to ammonia by loading Co3O4 on CuO to construct elecrocatalytic dual-sites.

Improving the performance of CuO in electrocatalytic nitrite reduction to ammonia (NIRA) is the priority for designing efficient NIRA electrocatalysts. The electrocatalytic activity of CuO was enhanced by growing Co3O4 nanospheres on it. By comparing Co3O4@CuO with the mechanically mixed CuO and Co3O4 on a rotating ring-disk electrode, we discovered that the enhancement was attributed to a dual-site catalytic pathway.

Electrocatalytic CO2 Upgrading to Triethanolamine by Bromine‐Assisted C2H4 Oxidation

AbstractThe electrocatalytic carbon dioxide (CO2) reduction is a promising approach for converting this greenhouse gas into value‐added chemicals, while the capability of producing products with longer carbon chains (Cn>3) is limited. Herein, we demonstrate the Br‐assisted electrocatalytic oxidation of ethylene (C2H4), a major CO2 electroreduction product, into 2‐bromoethanol by electro‐generated bromine on metal phthalocyanine catalysts. Due to the preferential formation of Br2 over *O or Cl2 to activate the C=C bond, a high partial current density of producing 2‐bromoethanol (46.6 mA⋅cm−2) was obtained with 87.2 % Faradaic efficiency. Further coupling with the electrocatalytic nitrite reduction to ammonia at the cathode allowed the production of triethanolamine with six carbon atoms. Moreover, by coupling a CO2 electrolysis cell for in situ C2H4 generation and a C2H4 oxidation/nitrite reduction cell, the capability of upgrading of CO2 and nitrite into triethanolamine was demonstrated.

Electrocatalytic CO2 Upgrading to Triethanolamine by Bromine-Assisted C2 H4 Oxidation.

The electrocatalytic carbon dioxide (CO2 ) reduction is a promising approach for converting this greenhouse gas into value-added chemicals, while the capability of producing products with longer carbon chains (Cn >3) is limited. Herein, we demonstrate the Br-assisted electrocatalytic oxidation of ethylene (C2 H4 ), a major CO2 electroreduction product, into 2-bromoethanol by electro-generated bromine on metal phthalocyanine catalysts. Due to the preferential formation of Br2 over *O or Cl2 to activate the C=C bond, a high partial current density of producing 2-bromoethanol (46.6 mA⋅cm-2 ) was obtained with 87.2 % Faradaic efficiency. Further coupling with the electrocatalytic nitrite reduction to ammonia at the cathode allowed the production of triethanolamine with six carbon atoms. Moreover, by coupling a CO2 electrolysis cell for in situ C2 H4 generation and a C2 H4 oxidation/nitrite reduction cell, the capability of upgrading of CO2 and nitrite into triethanolamine was demonstrated.

V-doped TiO2 nanobelt array for high-efficiency electrocatalytic nitrite reduction to ammonia

Electrocatalytic nitrite (NO2−) reduction to ammonia (NH3) has been an attractive topic, which not only removes NO2− pollutants existing in surface water and underground water but also synthesizes value-added NH3. Nevertheless, the inactive kinetics for direct six-electron NO2−-to-NH3 conversion makes it challenging to explore efficient electrocatalysts for the NO2− reduction reaction (NO2RR). Herein, we report a V-doped TiO2 nanobelt array on a titanium plate (V–TiO2/TP) as a highly efficient NO2RR electrocatalyst. The experimental results and theoretical calculations clarify that V doping can enhance the intrinsic electrical conductivity and effectively optimize the free energy of the TiO2 (101) crystal plane in the potential determining step, resulting in a positive effect on electrochemical NO2RR to NH3. The designed V–TiO2/TP exhibits an outstanding electrochemical NO2RR property with a high NH3 yield of 540.8 μmol h−1 cm−2 at −0.7 V and an excellent Faradaic efficiency of 93.2% at −0.6 V versus reversible hydrogen electrode, superior to TiO2/TP.

Ambient ammonia production via electrocatalytic nitrite reduction over MoO2 nanoparticles self-supported on molybdenum plate

Electrocatalytic reduction of nitrite (NO2–) is an environmentally friendly method for ambient ammonia (NH3) production, and the development of high–efficiency electrocatalysts is in urgent demand. Herein, we demonstrated that MoO2 nanoparticles self–supported on a molybdenum plate (MoO2/MP) could act as an excellent catalyst for the conversion of NO2– to NH3. The optimized catalyst can achieve an impressive NH3 yield of 8678.4 ± 187.4 μg h–1 cm–2 with high Faradaic efficiency of 94.5 ± 0.2 % at −0.8 V in the solution of 0.5 M Na2SO4 and 0.1 M NO2–, along with preferable durability. Additionally, density functional theory calculation reveals that the MoO2 (1¯11) surface has a high activity for NO2– reduction, with 0.38 eV as the potential determining step (*NO2 to NO2H), as well as severe suppress hydrogen evolution.

Buffer Assists Electrocatalytic Nitrite Reduction by a Cobalt Macrocycle Complex.

This work reports a combined experimental and computational study of the activation of an otherwise catalytically inactive cobalt complex, [Co(TIM)Br2]+, for aqueous nitrite reduction. The presence of phosphate buffer leads to efficient electrocatalysis, with rapid reduction to ammonium occurring close to the thermodynamic potential and with high Faradaic efficiency. At neutral pH, increasing buffer concentrations increase catalytic current while simultaneously decreasing overpotential, although high concentrations have an inhibitory effect. Controlled potential electrolysis and rotating ring-disk electrode experiments indicate that ammonium is directly produced from nitrite by [Co(TIM)Br2]+, along with hydroxylamine. Mechanistic investigations implicate a vital role for the phosphate buffer, specifically as a proton shuttle, although high buffer concentrations inhibit catalysis. These results indicate a role for buffer in the design of electrocatalysts for nitrogen oxide conversion.

High-Efficiency Ammonia Electrosynthesis on Anatase TiO2-x Nanobelt Arrays with Oxygen Vacancies by Selective Reduction of Nitrite.

Electrocatalytic reduction of nitrite to NH3 provides a new route for the treatment of nitrite in wastewater, as well as an attractive alternative to NH3 synthesis. Here, we report that an oxygen vacancy-rich TiO2-x nanoarray with different crystal structures self-supported on the Ti plate can be prepared by hydrothermal synthesis and by subsequently annealing it in an Ar/H2 atmosphere. Anatase TiO2-x (A-TiO2-x) can be a superb catalyst for the efficient conversion of NO2- to NH3; a high NH3 yield of 12,230.1 ± 406.9 μg h-1 cm-2 along with a Faradaic efficiency of 91.1 ± 5.5% can be achieved in a 0.1 M NaOH solution containing 0.1 M NaNO2 at -0.8 V, which also exhibits preferable durability with almost no decay of catalytic performances after cycling tests and long-term electrolysis. Furthermore, a Zn-NO2- battery with such A-TiO2-x as a cathode delivers a power density of 2.38 mW cm-2 as well as a NH3 yield of 885 μg h-1 cm-2.

Cu nanoparticles decorated juncus-derived carbon for efficient electrocatalytic nitrite-to-ammonia conversion

Electrocatalytic nitrite reduction to value-added NH3 can simultaneously achieve sustainable ammonia production and N-contaminant removal in natural environments, which has attracted widespread attention but still lacks efficient catalysts. In this work, Cu nanoparticles decorated juncus-derived carbon can be proposed as a high-active electrocatalyst for NO2−-to-NH3 conversion, obtaining a high Faradaic efficiency of 93.2% and a satisfactory NH3 yield of 523.5 μmol h−1 mgcat.−1. Density functional theory calculations were applied to uncover insightful understanding of internal catalytic mechanism.

Recent advances in electrocatalytic nitrite reduction.

Electrocatalytic nitrite reduction is of great significance for wastewater treatment and value-added chemicals synthesis. This review highlights the latest progress in electrochemical nitrite reduction to produce two types of products, including gaseous products (NO, N2O, N2) and liquid products (NH2OH and NH4+). The heterogeneous and homogeneous catalysts used in the corresponding reduction processes are introduced, with emphasis on the product selectivity regulation and reaction mechanism understanding. Finally, the challenges and opportunities in this field are analyzed as well. This review can provide guidelines for designing electrochemical systems with high efficiency and specificity for nitrite reduction.