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Room-temperature nitrate electroreduction can simultaneously synthesize ammonia and eliminate N-contaminants, which has attracted a lot of interest but still needs efficient electrocatalysts. Here, we report the in situ derivation of an amorphous cobalt borate (CoBi) film on a Co3O4 nanoarray on carbon cloth (Co3O4@CoBi/CC) for efficient ammonia generation via selective electroreduction of nitrate at room temperature and atmospheric pressure. In a neutral phosphate-buffered electrolyte containing 0.1 M NaNO3, such a catalyst exhibits a maximum ammonia yield rate of 6.80 mg/h/cm2 (−1.0 V vs RHE) and a high Faradaic efficiency of up to 97% (−0.7 V vs RHE). Besides, its catalytic activity remains stable in recycling tests and long-term electrolysis. An aqueous Zn nitrate battery with Co3O4@CoBi/CC as the cathode shows a high battery performance as well. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrate reduction reaction (NO3−RR) emerges as a highly efficient approach toward ammonia synthesis and degrading NO3− contaminant. In our study, CeO2 nanoparticles with oxygen vacancies (VO) decorated N-doped carbon nanorods on graphite paper (CeO2−x@NC/GP) were demonstrated as a highly efficient NO3−RR electrocatalyst. The CeO2−x@NC/GP catalyst manifests a significant NH3 yield up to 712.75 µmol·h−1cm−2 at −0.8 V vs. reversible hydrogen electrode (RHE) and remarkable Faradaic efficiency of 92.93% at −0.5 V vs. RHE under alkaline conditions, with excellent durability. Additionally, an assembled Zn-NO3− battery with CeO2−x@NC/GP as cathode accomplishes a high-power density of 3.44 mWcm−2 and a large NH3 yield of 145.08 µmol·h−1cm−2. Density functional theory results further expose the NO3− reduction mechanism on CeO2 (111) surface with VO. [ABSTRACT FROM AUTHOR]

Ambient electroreduction of nitrogen (N2) is considered as a green and feasible approach for ammonia (NH3) synthesis, which urgently demands for efficient electrocatalyst. Morphology has close relationship with catalytic activity of heterogeneous catalysts. Nanoribbon is attractive nanostructure, which possesses the flexibility of one-dimensional nanomaterials, the large surface area of two-dimensional nanomaterials, and lateral size confinement effects. In this work, Cu3P nanoribbon is proposed as a highly efficient electrocatalyst for N2-to-NH3 conversion under benign conditions. When measured in N2-saturated 0.1 M HCl, such Cu3P nanoribbon achieves high performance with an excellent Faradaic efficiency as high as 37.8% and a large yield of 18.9 µg·h−1µmgcat.−1 at −0.2 V. It also demonstrates outstanding stability in long-term electrolysis test at least for 45 h. [ABSTRACT FROM AUTHOR]

High‐performance earth‐abundant electrocatalysts for oxygen evolution reaction (OER) are highly desirable. In this report, we successfully synthesized amorphous Fe−P shell electrodeposited on Co(OH)F nanowire arrays supported on titanium mesh (Fe−P@Co(OH)F/TM) as an efficient catalyst for OER. Such catalyst exhibits excellent OER activity with a low overpotential of 267 mV to reach the geometrical current density of 10 mA cm−2 in 1.0 M KOH. In addition, it has good electrochemical durability to maintain its activity for at least 20 h. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of NO offers us an attractive alternative to traditional selective catalytic reduction process for harmful NO removal and simultaneous NH3 production, but it requires efficient electrocatalyst to enable the NO reduction reaction with high selectivity. Here, we report on the development of Bi nanoparticles/carbon nanosheet composite (Bi@C) for highly effective NO reduction electrocatalysis toward selective NH3 formation. Such Bi@C catalyst attains an impressive NH3 yield of 1,592.5 µg·hr−1·mgcat.−1 and a high Faradaic efficiency as high as 93% in 0.1 M Na2SO4 electrolyte. Additionally, it can be applied as efficient cathode materials for Zn−NO battery to reduce NO to NH3 with high electricity generation. [ABSTRACT FROM AUTHOR]

NH3 is an essential feedstock for fertilizer synthesis. Industry-scale NH3 synthesis mostly relies on the Haber-Bosch method, however, which suffers from massive CO2 emission and high energy consumption. Electrocatalytic NO3− reduction is an attractive substitute to the Haber-Bosch method for synthesizing NH3 under mild conditions. As this reaction will produce a variety of products, it highly desires efficient and selective electrocatalyst for NH3 generation. Here, we report in situ grown Fe3O4 particle on stainless steel (Fe3O4/SS) as a high-efficiency electrocatalyst for NO3− reduction to NH3. In 0.1 M NaOH with 0.1 M NaNO3, such Fe3O4/SS reaches a remarkable Faradaic efficiency of 91.5% and a high NH3 yield of 10,145 µg·h−1·cm−2 at −0.5 V vs. reversible hydrogen electrode (RHE). Furthermore, it owns robust structural and electrochemical stability. This work provides useful guidelines to expand the scope of metallic oxide electrocatalysts for NH3 synthesis. The catalytic mechanism is uncovered and discussed further by theoretical calculations. [ABSTRACT FROM AUTHOR]

Self-supported one-dimensional (1D) monoclinic nickel molybdate nanorods with abundant OVs on Ni foam (NiMoO 4 /NF) can achieve high Faraday efficiency of 94.49 ± 0.42% and a large ammonia yield of 18089.39 ± 227.98 μg h−1 cm−2 at –0.8V vs. RHE in 0.5 M Na 2 SO 4 and 0.1 M NO 2 – solution, together with preferable long-term stability. In addition, it was verified that Zn-NO 2 – battery with NiMoO 4 /NF as cathode delivers an ammonium yield of 1929.76 μg h−1 cm−2 and a Faradaic efficiency of 91.27% at 20 mA cm−2. [Display omitted] As an eco-friendly and sustainable strategy, the electrochemical reduction of nitrite (NO 2 –) can simultaneous generation of NH 3 and treatment of NO 2 – contamination in the environment. Herein, monoclinic NiMoO 4 nanorods with abundant oxygen vacancies self-supported on Ni foam (NiMoO 4 /NF) are considered high-performance electrocatalysts for ambient NH 3 synthesis by reduction of NO 2 −, which can deliver an outstanding yield of 18089.39 ± 227.98 μg h−1 cm−2 and a preferable FE of 94.49 ± 0.42% at −0.8 V. Additionally, its performance remains relatively stable during long-term operation as well as cycling tests. Furthermore, density functional theory calculations unveil the vital role of oxygen vacancies in promoting nitrite adsorption and activation, ensuring efficient NO 2 –RR towards NH 3. A Zn-NO 2 – battery with NiMoO 4 /NF as the cathode shows high battery performance as well. [ABSTRACT FROM AUTHOR]

Oxygen vacancies-rich monoclinic cobalt molybdate nanosheets on nickel foam (CoMoO 4 /NF) serve as highly effective catalysts for the electroreduction of nitrite (NO 2 −RR). In an aqueous solution containing 0.5M Na 2 SO 4 and 0.1M NO 2 −, the Faraday efficiency (FE) of CoMoO 4 /NF reaches an impressive 98.6 ± 0.02% at −0.8 V vs. RHE. Meanwhile, NH 3 yield demonstrates a commendable performance, attaining 32.72 ± 0.17 mg/h cm−2. Employing CoMoO 4 /NF as the cathode, the Zn−NO 2 − battery demonstrates a peak power density of 5.94 mW cm−2 alongside an NH 3 yield of 3.88 mg/h cm−2 and an FE of 91.88%. Furthermore, density functional theory calculations uncover the significant influence of oxygen vacancies on enhancing nitrite adsorption and activation over the CoMoO 4 surface and bring to light possible reaction pathways. [Display omitted] • Oxygen vacancies-rich CoMoO 4 /NF were fabricated through hydrothermal synthesis followed by calcination reduction. • The optimized catalyst can achieve a large NH 3 yield of 32.72 ± 0.17 mg−1 cm−2 and high FE of 98.6 % ± 0.02 % at –0.8 vs. RHE, as well as preferable long-term stability in 0.5 M Na 2 SO 4 and 0.1 M NO 2 –. • Zn-NO 2 – battery with NiMoO 4 /NF as cathode has a good energy supply of 5.94 mW cm−2 and simultaneously ammonium yield of 3.88 mg h−1 cm−2 and Faradaic efficiency of 91.88 % at 20 mA cm−2. • DFT calculations reveal that abundant oxygen vacancies can facilitate nitrite adsorption and activation, ensuring efficient NO 2 –RR towards NH 3. Electrocatalytic reduction is a promising method to remove NO 2 −; not only can it deal with environmental issues, but it can also recycle NO 2 − to form NH 3. This study involved the preparation of oxygen vacancies-rich monoclinic cobalt molybdate nanosheets on nickel foam (CoMoO 4 /NF) employing a hybrid approach of hydrothermal and calcination reduction techniques renders highly effective catalysts for electroreduction of nitrite (NO 2 −RR). The presence of oxygen vacancies increases carrier density, enhancing electrical conductivity, reducing resistance, and accelerating electron transfer. Additionally, it serves as an active site for absorbing NO 2 −. In an aqueous solution containing 0.5 M Na 2 SO 4 and 0.1 M NO 2 −, the Faraday efficiency (FE) of CoMoO 4 /NF reaches an impressive 98.6 ± 0.02 % at −0.8 V vs. RHE, and NH 3 yield demonstrates a commendable performance, attaining 32.72 ± 0.17 mg h−1 cm−2. Meanwhile, it exhibits robust and enduring characteristics throughout the stability tests. Employing CoMoO 4 /NF as the cathode, the Zn−NO 2 − battery demonstrates a peak power density of 5.94 mW cm−2 alongside an NH 3 yield of 3.88 mg h−1 cm−2 and an FE of 91.88 %. Furthermore, density functional theory calculations uncover the significant influence of oxygen vacancies on enhancing nitrite adsorption and activation over the CoMoO 4 surface and bring to light possible reaction pathways. [ABSTRACT FROM AUTHOR]

Ag nanoarray using NiO nanosheets array on carbon cloth as support behaves as a high-active and stable electrocatalyst for NO 2 – reduction into NH 3 with a remarkably yield up to 5,751 μg h−1 cm−2 (57,510 μg h−1 mg Ag -1) and a Faradaic efficiency as high as 97.7%. Density functional theory calculations was applied to uncover its catalytic mechanism. [Display omitted] Electrochemical reduction of nitrite to ammonia can simultaneously achieve ammonia synthesis and N -contaminant removal under mild conditions, which has attracted widespread attention but still lacks efficient catalysts. In this work, Ag nanoarray using NiO nanosheets array on carbon cloth as support is reported as an efficient electrocatalyst to selectively reduce nitrite to ammonia. In 0.1 M NaOH with 0.1 M NO 2 –, such catalyst exhibits a maximum ammonia yield of 5,751 μg h−1 cm−2 (57,510 μg h−1 mg Ag -1) and high Faradaic efficiency up to 97.7 %. Density functional theory calculations applied to uncover the catalytic mechanism of NO 2 – reduction reaction on Ag. [ABSTRACT FROM AUTHOR]

Ni 2 P nanosheet array supported on nickle foam enables ambient electrochemical NO 2 – reduction to NH 3 , achieving a large NH 3 yield rate of 2692.2 ± 92.1 μg h−1 cm−2 (3282.9 ± 112.3 μg h−1 mg cat. −1), a high Faraday efficiency of 90.2 ± 3.0%, and selectivity of 87.0 ± 1.7% at –0.3 V versus a reversible hydrogen electrode in 0.1 M phosphate buffer saline with 200 ppm NO 2 –. [Display omitted] Ammonia (NH 3) plays an important role in agriculture and industry. The industry-scale production mainly depends on the Haber-Bosch process suffering from issues of environment pollution and energy consumption. Electrochemical reduction can degrade nitrite (NO 2 –) pollutants in the environment and convert it into more valuable NH 3. Here, Ni 2 P nanosheet array on nickel foam is proposed as a 3D electrocatalyst for high-efficiency electrohydrogenation of NO 2 – to NH 3 under ambient reaction conditions. When tested in 0.1 M phosphate buffer saline with 200 ppm NO 2 –, such Ni 2 P/NF is able to obtain a large NH 3 yield rate of 2692.2 ± 92.1 μg h−1 cm−2 (3282.9 ± 112.3 μg h−1 mg cat. −1), a high Faradic efficiency of 90.2 ± 3.0%, and selectivity of 87.0 ± 1.7% at −0.3 V versus a reversible hydrogen electrode. After 10 h of electrocatalytic reduction, the conversion rate of NO 2 – achieves near 100%. The catalytic mechanism is further investigated by density functional theory calculations. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of nitrite (NO 2 –) is an environmentally friendly method for ambient ammonia (NH 3) production, and the development of high–efficiency electrocatalysts is in urgent demand. Herein, we demonstrated that MoO 2 nanoparticles self–supported on a molybdenum plate (MoO 2 /MP) could act as an excellent catalyst for the conversion of NO 2 – to NH 3. The optimized catalyst can achieve an impressive NH 3 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 Na 2 SO 4 and 0.1 M NO 2 –, along with preferable durability. Additionally, density functional theory calculation reveals that the MoO 2 (1 ¯ 11) surface has a high activity for NO 2 – reduction, with 0.38 eV as the potential determining step (*NO 2 to NO 2 H), as well as severe suppress hydrogen evolution. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A review based on metal–organic framework derived heteroatom-doped materials. • Preparation methods and applications in electrochemical fields are summarized. • Challenges and prospective applications of MOF derivatives are addressed. With the increasing demands for fuels, it's urgent to exploit energy devices with excellent performance. The MOF-derived materials are promising candidates for energy conversion and storage due to their large specific surface area, remarkable electrical conductivity and high mechanical strength. They can be prepared by calcination, in solution, etc. MOF-derived materials with heteroatom doping, such as nitrogen, phosphorus, and sulfur, possess characteristics of changing and promoting chemical composition and electronic structure, thus enhancing electrochemical performance. Herein, the latest progresses in MOF-derived N, P, S-doped materials for energy storage and conversion, including electrocatalytic water splitting, fuel cells, supercapacitors and batteries are introduced and summarized. Finally, the prospective applications of MOF-derived N, P, S-doped materials in energy storage and conversion are also concluded. [ABSTRACT FROM AUTHOR]

Co 2 AlO 4 /CC achieves superb NO 3 − reduction performances with a large NH 3 yield of 7.9 mg h−1 cm−2 and a Faradaic efficiency of 92.6%. Furthermore, the Co 2 AlO 4 /CC-based Zn-NO 3 − battery offers a high power density and a large NH 3 yield. [Display omitted] • A Co 2 AlO 4 nanosheet array acts as a 3D electrocatalyst for NO 3 − electroreduction. • It exhibits a superior catalytic performances for selective NH 3 generation. • It attains a large NH 3 yield of 7.9 mg h−1 cm−2 and a Faradaic efficiency of 92.6%. • Zn-NO 3 − battery with Co 2 AlO 4 /CC cathode offers high power densities and NH 3 yields. • DFT reveals that Co 2 AlO 4 (2 2 0) inhibits HER but shows high NO 3 − reduction activity. A Co 2 AlO 4 nanosheet array on carbon cloth (Co 2 AlO 4 /CC) is proposed as a superb electrocatalyst for converting nitrate (NO 3 −) to ammonia (NH 3). In 0.1 M PBS solution with 0.1 M NO 3 −, it attains an NH 3 yield of 7.9 mg h−1 cm−2 with a Faradaic efficiency of 92.6%, with high durability. A Zn-NO 3 − battery with such Co 2 AlO 4 /CC as cathode offers a power density of 3.43 mW cm−2 with an NH 3 yield of 750 μg h−1 cm−2. Theoretical calculations reveal that Al ions reduce the electron cloud density on the surface of Co, making it highly conducive to NO 3 − adsorption at Co sites. Additionally, Co 2 AlO 4 (2 2 0) surface inhibits hydrogen evolution reaction but is highly active for NO 3 − reduction with a low energetically uphill pathway (ΔG of 0.42 eV) for the potential-determining step (*NO 3 to *NO 3 H), much smaller than that of Co 3 O 4 (2 2 0) (ΔG of 0.83 eV). [ABSTRACT FROM AUTHOR]