Green ammonia synthesis using CeO2/RuO2 nanolayers on vertical graphene catalyst via electrochemical route in alkaline electrolyte

Şahin

ACS Appl. Mater. Interfaces

et al. 2022

Conventional ammonia production consumes significant energy and causes enormous carbon dioxide (CO2) emissions globally. To lower energy consumption and mitigate CO2 emissions, a facile, environmentally friendly, and cost-effective one-pot method for the synthesis of a ruthenium-based nitrogen reduction nanocatalyst has been developed using reduced graphene oxide (rGO) as a matrix. The nanocatalyst synthesis was based on a single-step simultaneous reduction of RuCl3 into ruthenium-based nanoparticles (Ru-based NPs) and graphene oxide (GO) into rGO using glucose as the reducing agent and stabilizer. The obtained ruthenium-based nanocatalyst with rGO as a matrix (Runano-based/rGO) has shown much higher catalytic activity at lower temperatures and pressures for ammonia synthesis than conventional iron catalysts. The rGO worked as a promising promoter for the electrochemical synthesis of ammonia due to its excellent electrical and thermal conductivity. The developed Runano-based/rGO nanocatalyst was characterized using transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), ultraviolet–visible (UV–vis) absorption spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS), inductively coupled plasma mass spectrometry (ICP-MS), and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the size of the Ru-based NPs on the surface of rGO was 1.9 ± 0.2 nm and the ruthenium content was 25.03 wt %. Bulk electrolysis measurements were conducted on thin-layer electrodes at various cathodic potentials in a N2-saturated 0.1 M H2SO4 electrolyte at room temperature. From the chronoamperometric measurements, the maximum faradic efficiency (F.E.) of 2.1% for ammonia production on the nanostructured Runano-based/rGO electrocatalyst was achieved at a potential of −0.20 V vs reversible hydrogen electrode (RHE). This electrocatalyst has attained a superior ammonia production rate of 9.14 μg·h–1·mgcat. –1. The results demonstrate the feasibility of reducing N2 into ammonia under ambient conditions and warrant further exploration of the nanostructured Runano-based/rGO for electrochemical ammonia synthesis.

Section: Resultssupporting

confidence: 56%

One-Pot Synthesis of Ruthenium-Based Nanocatalyst Using Reduced Graphene Oxide as Matrix for Electrochemical Synthesis of Ammonia

Şahin

ACS Appl. Mater. Interfaces

et al. 2022

ACS Appl. Energy Mater.

“…Then, the gas mixture of Ar (10 sccm), CH 4 (20 sccm), and H 2 (10 sccm) was introduced into the chamber using the mass flow controllers, and a constant pressure of 4.0 Pa was maintained. Then, the plasma was generated at a constant power of 1000 W for 10 min to facilitate the growth of microporous, vertically oriented, and interconnected 3D graphene sheets directly onto the NF substrate . The resulting vertical graphene structure was anticipated to offer an enhanced surface area and interaction sites, crucial for the decoration of ZIF-67 nanostructures and interaction with the electrolyte to promote efficient water oxidation.…”

Section: Methodsmentioning

confidence: 99%

ZIF-67 Nanostructures Anchored on 3D Graphene Sheets: A Non-noble Electrocatalyst for Efficient Oxygen Evolution Reaction

Choe,

Patil,

Kim

et al. 2024

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The efficiency of water electrolysis is heavily dependent on the oxygen evolution reaction. Overcoming the persistent challenge of developing electrocatalysts that exhibit high current density, low overpotential, and long-lasting performance is crucial. In this context, we introduce a promising electrocatalyst for water oxidation under alkaline conditions. This catalyst takes the form of a composite material composed of ZIF-67 and 3D graphene sheets, specifically designated as ZIF-67@3D graphene. 3D vertical graphene sheets were deposited on nickel foam (NF) using an inductively coupled plasma chemical vapor deposition system. ZIF-67 was synthesized via mechanical stirring, employing cobalt metal ions as the coordinating species, with 2-methylimidazole (2-MIM) serving as a ligand. The as-deposited 3D graphene sheets on nickel foam were integrated with a solution of ZIF-67 and subjected to stirring to yield the composite material. Our electrochemical investigation revealed that the ZIF-67@3D graphene composite displays enhanced catalytic performance compared to ZIF-67@NF. The composite exhibited an overpotential of 220 mV at a current density of 10 mA cm −2 , along with a Tafel slope of 170 mV dec −1 , in contrast to 290 mV at 10 mA cm −2 and a Tafel slope of 174 mV dec −1 for ZIF-67/NF alone. Additionally, the ZIF-67@3D graphene/NF composite achieved a current density of 50 mA cm −2 with an overpotential of only 380 mV. This notable enhancement in performance is attributed to the synergistic interactions between the metal−organic framework and graphene, which result in an improved current density and a decreased overpotential.

“…Recently, Jupiter Ionics electrolysis technology demonstrated green ammonia production technology for small-scale applications. 18 Ju et al 19 and MacFarlane et al 20 synthesized green ammonia by the alkaline electrochemical reduction of nitrogen at ambient temperature and pressure.…”

Section: Role Of Ammonia As An Energy Carriermentioning

confidence: 99%

Challenges and advancement in direct ammonia solid oxide fuel cells: a review

Dhawale,

Biswas,

Kaur

et al. 2023

Inorg. Chem. Front.

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