Promoting Nitrite-to-Ammonia Electroreduction over Amorphous CoS₂ Nanorods

Electrocatalytic nitrite reduction to ammonia (NO2RR) emerges as a promising route to simultaneously attain harmful NO2– removal and green NH3 synthesis. In this study, amorphous CoS2 nanorods (a-CoS2) are first demonstrated as an effective NO2RR catalyst, which exhibits the maximum FENH3 of 88.7% and NH3 yield rate of 438.1 μmol h–1 cm–2 at −0.6 V vs RHE. Detailed experimental and computational investigations reveal that the high NO2RR performance of a-CoS2 originates from the amorphization-induced S vacancies to facilitate NO2– activation and hydrogenation, boost the electron transport kinetics, and inhibit the competitive hydrogen evolution

An Amorphization-Engineered Catalyst for Electrocatalytic Reduction of Nitric Oxide to Ammonia

Electrocatalytic NO-to-NH3 conversion (NORR) provides a fascinating route toward the eco-friendly and valuable production of NH3. In this study, amorphous FeS2 (a-FeS2) is first demonstrated as a high-efficiency catalyst for the NORR, showing a maximum FENH3 of 92.5% with a corresponding NH3 yield rate of 227.1 μmol h–1 cm–2, outperforming most NORR catalysts reported earlier. Experimental measurements combined with theoretical computations clarify that the exceptional NORR activity of a-FeS2 originates from the amorphization-induced upshift of the d-band center to promote the NO activation and NO-to-NH3 hydrogenation energetics

Electrocatalytic NO Reduction to NH₃ on Mo₂C Nanosheets

Electrocatalytic reduction of NO to NH3 (NORR) emerges as a promising route for achieving harmful NO treatment and sustainable NH3 generation. In this work, we first report that Mo2C is an active and selective NORR catalyst. The developed Mo2C nanosheets deliver a high NH3 yield rate of 122.7 μmol h–1 cm–2 with an NH3 Faradaic efficiency of 86.3% at −0.4 V. Theoretical computations unveil that the surface-terminated Mo atoms on Mo2C can effectively activate NO, promote protonation energetics, and suppress proton adsorption, resulting in high NORR activity and selectivity of Mo2C

Iron Diboride (FeB₂) for the Electroreduction of NO to NH₃

We report iron diboride (FeB2) as a high-performance metal diboride catalyst for electrochemical NO-to-NH3 reduction (NORR), which shows a maximum NH3 yield rate of 289.3 μmol h–1 cm–2 and a NH3-Faradaic efficiency of 93.8% at −0.4 V versus reversible hydrogen electrode. Theoretical computations reveal that Fe and B sites synergetically activate the NO molecule, while the protonation of NO is energetically more favorable on B sites. Meanwhile, both Fe and B sites preferentially absorb NO over H atoms to suppress the competing hydrogen evolution

PdP₂ Nanoparticles on Reduced Graphene Oxide: A Catalyst for the Electrocatalytic Reduction of Nitrate to Ammonia

Palladium phosphides are explored as efficient catalysts for the electrocatalytic reduction of nitrate to ammonia (NRA). The explored PdP2 nanoparticles on reduced graphene oxide exhibit the maximum NH3 Faradaic efficiency of 98.2% with a corresponding NH3 yield rate of 7.6 mg h–1 cm–2 at −0.6 V (RHE). Theoretical calculations reveal that a PdP2 (011) surface can not only effectively activate and hydrogenate NO3– via a NOH pathway but also retard H adsorption to inhibit the competitive hydrogen evolution reaction

NiO Nanodots on Graphene for Efficient Electrochemical N2 Reduction to NH3

Current artificial NH3 synthesis relies heavily on the Haber–Bosch process that involves enormous energy consumption and huge CO2 emission. The electrochemical N2 reduction reaction (NRR) offers an eco-friendly and sustainable alternative but demands cost-effective and efficient NRR electrocatalysts. Herein, NiO nanodots (∼2 nm) supported on graphene (NiO/G) were developed as a high-performance NRR electrocatalyst at ambient conditions. Electrochemical tests indicated that the NiO/G exhibited a high NH3 yield (18.6 μg h–1 mg–1) and Faradaic efficiency (7.8%) at −0.7 V vs reversible hydrogen electrode, outperforming the most reported NRR electrocatalysts. Experimental and density functional theory (DFT) results revealed that NiO was the dominating active center, and nanodot structure enabled the NiO to expose more active sites. DFT results further demonstrated that the distal associative route was the preferable NRR pathway with *N2 → *NNH being the rate-determining step

Electroreduction of Nitrite to Ammonia over a Cobalt Single-Atom Catalyst

Electrochemical nitrite-to-ammonia reduction (NO2RR) holds great promise for converting harmful NO2– into valuable NH3. Herein, we develop Co single atoms dispersed on a C3N4 substrate (Co1/C3N4) as an efficient catalyst toward the NO2RR. Experimental and theoretical investigations reveal that single-atom Co sites can effectively active NO2– and optimize the formation energy of the key *NOH intermediate to promote the NO2– → NH3 energetics. Remarkably, Co1/C3N4 equipped in a flow cell delivers the exceptional NH3–Faradaic efficiency of 97.9% and NH3 yield rate of 1080.3 μmol h–1cm–2 at an industrial-level current density of 355 mA cm–2, along with a long-term durability of 100 h of electrolysis, showing the considerable potential for practical NH3 electrosynthesis

Atomically Dispersed W₁–O₃ Bonded on Pd Metallene for Cascade NO Electroreduction to NH₃

Electrocatalytic NO reduction to NH3 (NORR) offers a prospective method for removing hazardous NO and producing valuable NH3 simultaneously. Herein, we demonstrate that atomically dispersed W on Pd metallene (W1Pd) can be an efficient and robust NORR catalyst. Atomic coordination characterizations unravel that W single atoms exist as W1–O3 moieties bonded on Pd metallene. In situ spectroscopic measurements and theoretical calculations reveal the synergistic cascade effect of W1–O3 and Pd metallene to promote the NORR energetics of W1Pd, in which the activation and hydrogenation of NO occur on W1–O3, while Pd metallene dissociates H2O and donates protons required for hydrogenation of NO to NH3. Consequently, W1Pd exhibits an NH3 yield rate of 758.5 μmol h–1 cm–2 with an NH3-Faradaic efficiency of 91.3% in a flow cell (272.1 μmol h–1 cm–2 and 93.7% in H-type cells), ranking almost the highest performance among all reported NORR catalysts

Sub-nm RuO_<i>x</i> Clusters on Pd Metallene for Synergistically Enhanced Nitrate Electroreduction to Ammonia

The electrochemical nitrate reduction to ammonia reaction (NO3RR) has emerged as an appealing route for achieving both wastewater treatment and ammonia production. Herein, sub-nm RuOx clusters anchored on a Pd metallene (RuOx/Pd) are reported as a highly effective NO3RR catalyst, delivering a maximum NH3-Faradaic efficiency of 98.6% with a corresponding NH3 yield rate of 23.5 mg h–1 cm–2 and partial a current density of 296.3 mA cm–2 at −0.5 V vs RHE. Operando spectroscopic characterizations combined with theoretical computations unveil the synergy of RuOx and Pd to enhance the NO3RR energetics through a mechanism of hydrogen spillover and hydrogen-bond interactions. In detail, RuOx activates NO3– to form intermediates, while Pd dissociates H2O to generate *H, which spontaneously migrates to the RuOx/Pd interface via a hydrogen spillover process. Further hydrogen-bond interactions between spillovered *H and intermediates makes spillovered *H desorb from the RuOx/Pd interface and participate in the intermediate hydrogenation, contributing to the enhanced activity of RuOx/Pd for NO3–-to-NH3 conversion