Vanadium Nitride Supported on N-Doped Carbon as High-Performance ORR Catalysts for Zn–Air Batteries

Abstract

It is desirable to prepare low-cost non-noble metal catalysts using a simple and efficient method. Herein, we display for the first time that nitrogen-doped hierarchical porous carbon-supported vanadium nitride (VN/NC/C-x) catalysts can be regulated by dicyandiamide (DCDA). The introduction of DCDA not only effectively controls the pore structure, but also plays an important role in adjusting oxygen vacancies and d-electrons. In addition, DCDA is not only a significant raw material for the N-doped carbon, but also a nitrogen source for the preparation of vanadium nitride. The VN/NC/C-3 catalyst was prepared after optimization of the preparation parameters, and the macro/micro structure demonstrates a superior ORR performance in alkaline media with a positive onset potential of 0.85 V and a half-wave potential of 0.75 V, the limiting current density is as high as 4.52 mA·cm−2, and the Tafel slope is only 75.54 mV·dec−1. The VN/NC/C-3-based Zn–air battery exhibits a highest peak power density (161.82 mW∙cm−2) and an excellent energy density (702.28 mAh·kgZn−1 and 861.51 Wh·kgZn−1). This work provides a valuable synthetic approach for the preparation of other transition metal nitride catalysts with a relative economic value and high performance.

Machine-Learning-Assisted Aggregation-Induced Emissive Nanosilicon-Based Sensor Array for Point-of-Care Identification of Multiple Foodborne Pathogens

“…Besides, the continuous small peaks ranging of 1400–1600 cm –1 of prepared nanosilicons could be ascribed to the aromatic ring. , Moreover, X-ray photoelectron spectroscopy was used to further study chemical bonds of the as-synthesized nanosilicons. As illustrated in Figure D, peaks at ∼284.37, ∼285.29, and ∼288.72 eV of TPE- COOH -SiO 2 NPs could be assigned to CC bond, CC bond, and O–CO group of TPE- COOH , respectively. − Besides, peaks at ∼284.58 and ∼286.26 eV of TPE- NH 2 -SiO 2 NPs could be attributed to CC bond and C–N bond of TPE- NH 2 , respectively. − Moreover, peaks at ∼284.18, ∼284.99, ∼286.07, and ∼291.87 eV of TPE- CHO -SiO 2 NPs were because of CC bond, CC bond, CO bond, and C–C of TPE- CHO , respectively. − Meanwhile, peaks of ∼284.42 and ∼285.47 eV of TPE-SiO 2 NPs could be attributed to C–C/CC bond and CC bond of TPE, respectively. , Additionally, the peak of ∼400.36 eV of TPE- NH 2 -SiO 2 NPs in N 1s spectra could be assigned to – NH 2 of TEP- NH 2 (Figure E) . Subsequently, fluorescent behaviors of nanosilicons were investigated by fluorescence lifetime and fluorescence spectrum.…”

Heterostructure NiCo-Alloy Nanosheet Embedded Ceria Nanorods: A Highly Efficient Bifunctional Electrocatalyst toward Oxygen Evolution Reaction and Oxygen Reduction Reaction

“…Rechargeable metal–air batteries have attracted the attention of researchers to meet the increasing demands of energy due to their high energy densities, sustainability, and environment-friendly nature. − The core catalytic processes of the metal–air battery technology, i.e., oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), involve multielectron transfer steps, leading to slow kinetics and high overpotential (η). The design of electrocatalysts to lower the energy barrier of the above half-reactions with low cost and long-term durability is thus a challenging task. − Carbon-based materials have been enormously used for ORR and OER.…”

Electrocatalytic Oxygen Reduction Reaction by the Pd/Fe-N-C Catalyst and Application in a Zn–Air Battery

“…Unfortunately, the slow kinetic characteristics of the oxygen reduction reaction (ORR), which occurs at the cathode, seriously limits their efficiency; therefore, it is necessary to further boost the ORR activity of catalysts [1]. Platinum-based catalysts, represented by the commercial Pt/C catalyst, exhibit a good ORR activity, but their wide application is highly hindered by the low reserve and high cost of the Pt sources [2][3][4][5][6][7][8]. Palladium (Pd) has very similar atomic size, crystal structure, and electronic structure to those of platinum, indicating its potential application for the ORR.…”