The quasi-paralleled and interlaced nanosheet arrays of NiMn layered double hydroxides are successfully grown on KCu7S4 microwires with quasi-one-dimensional channel by tuning the concentration of the metal ions.
Multifunctional properties, including energy storage and sensitive diagnosis, are highly demanded for high-performance supercapacitors and sensors. Herein, we describe a facile method for the synthesis of a multitasking bacterial cellulose@Ni(OH) paper for use as a flexible 2 supercapacitor electrode with excellent energy storage performance and a sensing platform for high-sensitivity detection of H O. Monodispersed 2 2 surfactant-free Ni(OH) particles with a large fraction of edge sites were anchored on the cellulose fiber network, providing a bendable, 2 freestanding, and hydrophilic material, and leading to attractive electrochemical properties. As expected, this flexible electrode exhibited a-2 remarkable areal capacitance of ~2047 mF cm and high flexibility allowing it to be bent to arbitrary angles. As a nonenzymatic H O detection 2 2-1 electrochemical electrode, it displayed a fast amperometric response with a linear range of 0.1-12.4 mM, acceptable sensitivity (~3.79 uA mM-2 cm), and low detection limit (~0.28 μM, S/N=3). The versatility of the electrode can be demonstrated by its high selectivity in the presence of interfering species, good reliable detection, and also its ability to detect H O in real samples. The simple, low-cost, and general strategy presented 2 2 herein can be extended to the preparation of other biomass materials and open up new opportunities for flexible electronic devices.
Catalytically active carbons derived from plant biomass are conducive to the construction of renewable energy source system and utilization of sustainable resources. In this article, natural cattail fibers are used to fabricate porous nitrogen-doped carbon via direct chemical activation and heteroatom modification treatments. The graphene-like sheets from biomass pyrolysis are assembled into three-dimensional carbon frameworks. The chemical activation of KHCO3 generated unique porous structure and N-containing molecules pyrolysis modification provided nitrogen doping atoms. High surface area up to 2,345 m2·g−1 with simultaneous hierarchical pores (from micro to meso and macro) with abundant edge defects are achieved for these carbon materials. These materials have a very large external surface area up to 1,773 m2·g−1. The above strategy exhibits a significant synergistic effect on the improvement of catalytic properties toward hydrogen evolution reaction and oxygen reduction reaction. The small over potentials and Tafel slopes of these catalytically active carbons demonstrate excellent potential applications in renewable energy conversion and storage systems. This research established a new link among environmental improvement, biomass conversion and renewable energy utilization.
Oxalate-coordinated transition metal-based electrocatalysts
have
recently been shown to be very efficient for oxygen evolution reaction
(OER). However, the role of oxalate ligands has not been fully revealed.
Here, the effect of oxalate ligands with two −COO functional
groups on the surface of bimetallic sulfides is revealed. Through
ex situ Fourier transform infrared, X-ray diffraction, X-ray photoelectron
spectroscopy, and other material characterization techniques and in
situ electrochemical characterization techniques, it is proved that
the suitable oxalate-coordinated FeNi bimetallic sulfide (Fe–Ni3S2/OXs) has the best OER catalytic activity, which
can be attributed to the synergistic effect of the high-valence metal
sites and the proton center of the carboxyl functional group in oxalate.
The results of the density functional theory calculation show that
oxalate coordination can effectively optimize the adsorption–dissociation
performance of the catalyst surface for OH– and
provide a proton adsorption center, thereby promoting the Gibbs’s
free energy of reaction intermediates. And the overpotential of 260
mV (90% IR) is observed at the geometric current density of 100 mA
cm–2 in 1 M KOH solution, and the catalytic performance
of OER is proved to be strongly associated with the oxalate-coordinated
concentration on the support surface. And its Tafel slope reaches
57 mV dec–1, which has excellent OER catalytic reaction
kinetics. This work reveals the effect of oxalate ligands on OER activity
and provides a promising way for the preparation of efficient basic
oxygen evolution electrocatalysts.
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