Enhancement of Nitrate‐to‐Ammonia on Amorphous CeO_x‐Modified Cu via Tuning of Active Hydrogen Supply

Abstract

The electrochemical nitrate reduction reaction (NO3RR) is an environment‐friendly and promising alternative to the conventional Haber–Bosch ammonia synthesis process, which is a complex process of proton‐coupled electron transfer. Hereon, the amorphous CeOx support introduced to construct Cu/a‐CeOx heterostructure is prepared to provide sufficient *H and synergistically catalyze the NO3RR. Cu/a‐CeOx achieves a maximum ammonia yield of 1.52 mmol h−1 mgcat−1. In the flow cell, the NH3 yield reaches 17.93 mmol h−1 mgcat−1 at 1 A cm−2, which exceeds most of the state‐of‐the‐art catalysts. In situ X‐ray diffraction (XRD) and in situ Raman observe that the catalyst undergoes structural reconfiguration under operating conditions, thus confirming that Cu2O is not the true active center in the catalytic process. Furthermore, in situ characterizations and density functional theory (DFT) calculations demonstrate that the amorphous CeOx in Cu/a‐CeOx modulates the electronic structure of Cu and overcomes the higher potential barrier required for the decomposition of water on Cu, which greatly facilitates the hydrolysis process and provides a higher H‐coverage rate for the hydrogenation of NO3−, realizing a dynamic equilibrium between the production and consumption of active hydrogen. This component design strategy centered on the amorphous structure opens up a new pathway for the electrochemical NO3RR.

Efficient Synthesis of Co-Based Electrocatalysts from Waste Batteries and Distillers’ Grains toward Nitrate Wastewater to Ammonia

“…The characteristic peak at 1210 cm –1 belongs to the *NO 2 intermediate, the characteristic peak at 1404 cm –1 belongs to the *NH x intermediate, the characteristic peak at 1523 cm –1 belongs to the *NH, and the characteristic peak at 1650 cm –1 belongs to the product NH 3 , respectively. In addition, the characteristic peak at 3535 cm –1 is the absorption peak of NH 2 . , The peak intensities of *NH x , NH 2 , and NH 3 increases significantly with increasing applied potentials, demonstrating the occurrence of electrochemical NO 3 – reduction to NH 3 . No intermediate products in the *NOH-type reaction pathway were detected, and finally, based on the results of the Online DEMS and In situ ATR-SEIRAS, it was hypothesized that NO 3 * → NO 2 * → NO* → N* → NH* → NH 2 * → NH 3 * was the main reaction pathway.…”

“…In addition, the characteristic peak at 3535 cm −1 is the absorption peak of NH 2 . 41,42 The peak intensities of *NH x , NH 2 , and NH 3 increases significantly with increasing applied potentials, demonstrating the occurrence of electrochemical − has a low reaction-free energy, is easily reduced, and accumulates little NO 2 , which leads to a high selectivity for NH 3 . 44,45 The adsorption energy of the deoxygenation step shows a decreasing trend due to the spontaneous exothermic reaction from *NO 3 to *N. 46 The energy barrier height of NC during *N hydrogenation is 0.32 eV (*N → *NH); in contrast, the energy barrier height of Co-NPs-2 is lower than that of NC (0.22 eV).…”

Ru-Doped NiFe-MIL-53 with Facilitated Reconstruction and Active Hydrogen Supplement for Enhanced Nitrate Reduction

“…To date, the NO 3 RR for ammonia production is an alternative method using nitrate and water as feedback . As a prevalent nitrogen source, nitrate (NO 3 – ) exhibits high solubility in water, relatively weak NO bond energy (204 kJ mol –1 ), and rapid reduction kinetics . Moreover, the excessive accumulation of NO 3 – in groundwater and industrial pollutants harms human health and causes plenty of environmental problems .…”

Achieving efficient urea electrosynthesis through improving the coverage of a crucial intermediate across a broad range of nitrate concentrations

“…27 However, the above reports neglected the issue of water dissociation, which provides *H. It is known that the preparation of urea by electrocatalytic C–N coupling is a continuous hydrogenation process, which heavily depends on the activated hydrogen (*H) produced by the Volmer process during water dissociation. 28–30 Therefore, efficient multi-site catalysts need to be constructed to activate both NO 3 − and CO 2 and to promote water dissociation as well as to appropriately regulate *H adsorption.…”