1D/3D Heterogeneous Assembling Body of Cobalt Nitrides for Highly Efficient Overall Hydrazine Splitting and Supercapacitors

Abstract

Herein, the construction of a heterostructured 1D/3D CoN‐Co2N@NF (nickel foam) electrode used for thermodynamically favorable hydrazine oxidation reaction (HzOR), as an alternative to sluggish anodic oxygen evolution reaction (OER) in water splitting for hydrogen production, is reported. The electrode exhibits remarkable catalytic activities, with an onset potential of −0.11 V in HzOR and −71 mV for a current density of 10 mA cm−2 in hydrogen evolution reaction (HER). Consequently, an extraordinary low cell voltage of 53 mV is required to achieve 10 mA cm−2 for overall hydrazine splitting in a two‐electrode system, demonstrating significant energy‐saving advantages over conventional water splitting. The HzOR proceeds through the 4e− reaction pathway to release N2 while the 1e− pathway to emit NH3 is uncompetitive, as evidenced by differential electrochemical mass spectrometric measurements. The X‐ray absorption spectroscopy, in situ Raman spectroscopy, and theoretical calculations identify cobalt nitrides rather than corresponding oxides/(oxy)hydroxides as catalytic species for HzOR and illustrate advantages of heterostructured CoN‐Co2N in optimizing adsorption energies of intermediates/reagents and promoting catalytic activities toward both HzOR and HER. The CoN‐Co2N@NF is also an excellent supercapacitive material, exhibiting an increased specific capacity (938 F g−1 at 1 A g−1) with excellent cycling stability (95.8%, 5000 cycles).

Taking Advantage of Potential Coincidence Region: Insights into Gas Production Behavior in Advanced Self-Activated Hydrazine-Assisted Alkaline Seawater Electrolysis

“…As shown in Figure d, FeCoP/NF exhibits higher electrocatalytic HzOR activity with higher reactive current densities at lower overpotentials, reaching a current density of 10 mA cm –2 at −127 mV, which is much lower than 22 mV for FeP/NF, −98 mV for CoP/NF, and many other recently reported highly efficient electrocatalysts (Figure g and Table S3). − HzOR under alkaline conditions is a four-electron transfer process N 2 H 4 + OH − → N 2 normalH 3 * + H 2 normalO + e − N 2 normalH 3 * + OH − → N 2 normalH 2 * + H 2 normalO + e − N 2 normalH 2 * + OH − → N 2 H * + H 2 normalO + e − N 2 H * + OH − → N 2 …”

Manipulating Dual-Metal Catalytic Activities toward Organic Upgrading in Upcycling Plastic Wastes with Inhibited Oxygen Evolution

“…Electrocatalytic water splitting emerges as a cost-effective and sustainable strategy for clean hydrogen production, ideally driven by renewable energy sources. − Unfortunately, the sluggish kinetics inherent in the oxygen evolution reaction (OER) significantly impede overall efficiency, necessitating elevated voltages for substantial H 2 generation. − Consequently, there exists a compelling imperative to explore hydrogen generation methodologies with alternative anodic processes that offer enhanced affordability and superior thermodynamic feasibility compared to the OER. The electrocatalytic landscape has notably propelled the efficient and selective transformation of diverse organic compounds, encompassing straightforward alcohols and oxygenates. − A particularly intriguing paradigm has recently surfaced, advocating the substitution of OER with the electro-oxidation of waste plastic derivatives, a sustainable approach that complies with the circular economy. , This electro-oxidation not only demonstrates a theoretically lower potential than OER but also yields a series of valuable carbonyl chemicals, such as formate, 2,5-furandicarboxylate, glycolate, and adipate, diverging from the less valuable O 2 production. − Nevertheless, these substituting reactions may still be affected by competitive OER, resulting in decreased Faraday efficiency (FE) especially at elevated potentials for industrial current densities.…”

Dual-independent active sites for efficient hydrogen production

“…Just recently, some Co-based materials have been investigated and explored as superior electrocatalysts for the HzOR, such as Co/CF, CoN, CoNC and CoNi@NC, due to the low adsorption energy barrier and high activity of Co sites. 13,29–31 With regard to the HER electrocatalysts, transition metal carbides (TMCs) with a special metallic packed structure have been extensively investigated for electrocatalysts because of their high thermal and electrical conductivity, excellent mechanical strength and chemical stability, wide pH compatibility and durability. 32–34 Although some progress on HER/HzOR electrocatalysts has been achieved, very few candidates can satisfy the needs for practical applications owing to the totally different catalytic reaction mechanism and active sites.…”