Two‐dimensional Cu Plates with Steady Fluid Fields for High‐rate Nitrate Electroreduction to Ammonia and Efficient Zn‐Nitrate Batteries

The nitrate electroreduction reaction (NO3RR) offers an eco‐friendly alternative to the Haber–Bosch technology for ammonia (NH3) synthesis. However, the complex reaction process and diverse products make efficient NH3 synthesis challenging. Therefore, the rational design and preparation of highly efficient electrocatalysts are crucial for NO3RR. Herein, ultrathin copper‐nickel oxide (Cu‐NiO) nanosheets (Cu‐NiO UTNSs) are synthesized via the cyanogel‐NaBH4 hydrolysis‐reduction method, which are applied for the cathodic NO3 RR to NH3‐assisted with the anodic sulfur ion (S2−) oxidation reaction (SOR) in an electrolyzer. The ultrathin nanosheet structure, the interaction between NiO and Cu, and the formation of oxygen vacancy contribute to generating the rich active sites, regulating the electronic structure, and improving the substance adsorption. Thus, the Cu‐NiO UTNSs exhibit excellent electrocatalytic performance for NO3RR and SOR. As a bifunctional Cu‐NiO UTNSs||Cu‐NiO UTNSs electrolyzer, it can reach 10 mA cm−1 at only 0.1 V for NO3−‐to‐NH3 conversion at the cathode and S2−‐to‐S8 conversion at the anode. This work provides a promising approach for producing value‐added chemicals at a low electrolysis voltage and a strategy for pollutant treatment.

Copper–Nickel Oxide Nanosheets with Atomic Thickness for High‐Efficiency Sulfur Ion Electrooxidation Assisted Nitrate Electroreduction to Ammonia

Wang,

Hong,

Shao

et al. 2024

Engineering Nickel Dopants in Atomically Thin Molybdenum Disulfide for Highly Efficient Nitrate Reduction to Ammonia

Lv,

Sun,

Wang

et al. 2024

The electrocatalytic nitrate reduction reaction (NO3−RR) presents a promising pathway for achieving both ammonia (NH3) electrosynthesis and water pollutant removal simultaneously. Among various electrocatalysts explored, 2D materials have emerged as promising candidates due to their ability to regulate electronic states and active sites through doping. However, the impact of doping effects in 2D materials on the mechanism of NO3−RR remains relatively unexplored. Here, Ni‐doped MoS2 (Ni‐MoS2) nanosheets are investigated as a model system, demonstrating enhanced NO3−RR performance compared to undoped counterparts. By controlling the doping concentration, the Ni‐MoS2 nanosheets achieve a remarkable faradic efficiency (FE) of 92.3% for NH3 at −0.3 VRHE with excellent stability. The mechanistic studies reveal that the elevation of the NO3−RR performances originates from the generation of more active hydrogen and the acceleration of the reaction from nitrite (NO2−) to NH3 facilitated by Ni doping. Combining the experimental observations and theoretical calculations it is revealed that the appropriate Ni doping level in MoS2 can enhance *NO3 adsorption strength, thereby facilitating subsequent electrocatalytic steps. Together with the demonstration of Zn−NO3− and Zn−NO2− battery devices, the work provides new insights into the design and regulation of the active sites in 2D material catalysts for efficient NO3−RR.

Tandem Active Sites in Cu/Mo‐WO₃ Electrocatalysts for Efficient Electrocatalytic Nitrate Reduction to Ammonia

Dai,

Li,

et al. 2025

Electrocatalytic NO3− reduction to NH3 is a promising technique for both ammonia synthesis and nitrate wastewater treatment. However, this conversion involves tandem processes of H2O dissociation and NO3− hydrogenation, leading to inferior NH3 Faraday efficiency (FE) and yield rate. Herein, a tandem catalyst by anchoring atomically dispersed Cu species on Mo‐doped WO3 (Cu5/Mo0.6‐WO3) for the NO3RR is constructed, which achieves a superior FENH3 of 98.6% and a yield rate of 26.25 mg h−1 mgcat−1 at −0.7 V (vs RHE) in alkaline media, greatly exceeding the performance of Mo0.6‐WO3 and Cu5/WO3 counterparts. Systematic electrochemical measurement results reveal that the promoted activation of NO3− on Cu sites, accompanying accelerated water dissociation producing active hydrogens on Mo sites, are responsible for this superior performance. In situ infrared spectroscopy and theoretical calculation further demonstrate that atomically dispersed Cu sites accelerate the conversion of NO3− to NO2−, and the Mo dopant activates adjacent Cu sites, resulting in the decreased energy barrier of *NO2 to *NO and the stepwise hydrogenation processes, making the synthesis of NH3 thermodynamically favorable. This work demonstrates the critical role of tandem active sites at atomic level in enhancing the electrocatalytic NO3− reduction to NH3, paving a feasible avenue for developing high‐performance electrocatalysts.