Facile design of ultrafine CuFe2O4 nanocrystallines coupled porous carbon nanowires: Highly effective electrocatalysts for hydrogen peroxide reduction and the oxygen evolution reaction

Designing low-cost, high-efficiency and non-noble metal-based electrocatalysts is fairly essential for the commercial utilization of electrochemical sensors and energy conversion devices. Low-cost CuFe2O4 spinel has been widely researched as an electrocatalyst in electrochemical sensors and catalysis. Nevertheless, the low utilization of active sites in bulk CuFe2O4 and the poor electro conductivity of CuFe2O4 invariably restrict its upgrade in catalytic efficiency. Herein, by utilizing the facile electro-spinning technique and without involving any template or surfactant, we successfully design three-dimensional (3D) hierarchically porous architecture woven by abundant ultrafine CuFe2O4 crystal-coupled porous carbon nanowires (denoted as CuFe2O4/PCFs). Characterization results verify the 3D net-like textural structures of CuFe2O4/PCFs. Especially, the hierarchically porous structure, high surface area, and abundant carbon edges boost the uniform dispersion of tiny CuFe2O4 crystals; these obviously promote the amounts of electrochemically available CuFe2O4 active sites while decreasing the mass transport resistance of CuFe2O4/PCFs in electrocatalytic processes. Meanwhile, introducing carbon matrices can drastically enhance the electrical conductivity of CuFe2O4/PCF nanowires. All these advances in structural and physical performances truly make tremendous progress for CuFe2O4/PCFs for H2O2 reduction and oxygen evolution reaction (OER) catalysis compared with bulk CuFe2O4. For instance, the CuFe2O4/PCF catalyst exhibits a high sensitivity of 69.18 mu A mM(-1) cm(-2), low detection limit of 1.20 mu M and wide linear range of 0.11-22.0 mM for H2O2 sensing. Meanwhile, the CuFe2O4/PCF catalyst just needs a potential value of 1.589 V (vs. reversible hydrogen electrode) to achieve the OER catalysis current density of 10 mA cm(-2) in 1.0 M KOH, it only shows a small Tafel slope of 89.34 mV dec(-1) for the OER as well. Our catalyst design strategy of CuFe2O4/PCF nanowires not only demonstrates the successful design of a novel high-efficiency non-noble-metal catalyst for both OER and H2O2 reduction catalysis but also affords a new methodology for boosting the electrocatalytic abilities of spinel-type hybrid materials by designing a 3D structure and improving conductivity. (C) 2019 Elsevier B.V. All rights reserved.