Electrospun Carbon Nanofibers with Embedded Co-Ceria Nanoparticles for Efficient Hydrogen Evolution and Overall Water Splitting

Abstract

In this study, simple electrospinning combined with pyrolysis were used to fabricate transition-metal-based-nanoparticle-incorporated carbon nanofiber (CNF) electrocatalysts for a high-efficiency hydrogen evolution reaction (HER) and overall water splitting. Co-CeO2 nanoparticle-incorporated carbon nanofibers (Co-CeO2@CNF) exhibit an outstanding electrocatalytic HER performance with an overpotential and Tafel slope of 92 mV and 54 mV/dec, respectively. For the counterpart, electrolysis, we incorporate the widely used Ni2Fe catalyst with a high oxygen evolution reaction (OER) activity into the carbon nanofiber (Ni2Fe@CNF). To evaluate their electrochemical properties for the overall water splitting, Co-CeO2@CNF and Ni2Fe@CNF were used as the HER and OER electrocatalysts in an alkaline electrolyzer. With the paired Co-CeO2@CNF and Ni2Fe@CNF electrodes, an overall water splitting current density of 10 mA/cm2 was achieved by applying 1.587 V across the electrodes with a remarkably lower overpotential of 257 mV compared to that of an electrolyzer comprised of Pt/C and IrO2 electrodes (400 mV). Owing to the conformal incorporation of nanoparticles into the CNF, the electrocatalysts exhibit significant long-term durability over 70 h of overall water splitting. This study provides rational designs of catalysts with high electrochemical catalytic activity and durability to achieve overall water splitting.

Recent Advances of CeO2‐Based Electrocatalysts for Oxygen and Hydrogen Evolution as well as Nitrogen Reduction

“…Kim's group explored carbon nanofibers as support materials to embed cobalt-ceria nanoparticles by simple electrodeposition and pyrolysis methods to increase their hydrogen evolution activity. [121] At the current density of 10 mA/cm 2 , the overpotential of CoÀ CeO 2 @CNF is only 92 mV, much lower than that of Co@CNF (270 mV) and CeO 2 @CNF (381 mV), and the slope of Tafel is 54 mV/dec. Three-dimensional reduced graphene oxide has also been selected as support to decorate CeO 2 hollow microspheres on it to fabricate hybrid 3D-rGOÀ CeO 2 composite as electrocatalyst for HER with a η 10 of 0.34 V and a Tafel slope of 112.8 mV • dec À 1 .…”

“…It can be envisioned that other carbon materials can also be investigated as excellent supports. Kim′s group explored carbon nanofibers as support materials to embed cobalt‐ceria nanoparticles by simple electrodeposition and pyrolysis methods to increase their hydrogen evolution activity [121] . At the current density of 10 mA/cm 2 , the overpotential of Co−CeO 2 @CNF is only 92 mV, much lower than that of Co@CNF (270 mV) and CeO 2 @CNF (381 mV), and the slope of Tafel is 54 mV/dec.…”

Construction of FeCo2O4@N-Doped Carbon Dots Nanoflowers as Binder Free Electrode for Reduction and Oxidation of Water

“…Electrochemical water splitting has attracted extensive interest as a desirable method to produce renewable energy in the form of hydrogen fuels (H 2 ) [ 1 , 2 , 3 , 4 ]. Water splitting is mainly accompanied by a hydrogen evolution reaction (HER) which is thermodynamically feasible [ 5 , 6 ] and an oxygen evolution reaction (OER) which interferes in the water splitting process due to sluggish four proton-coupled electron transfer [ 7 ]. Hence, in order to overcome the high activation barrier of OER, a large overpotential ( η ) is needed in order to practically produce H 2 [ 8 ].…”

Electronic modulation and interface engineering of electrospun nanomaterials‐based electrocatalysts toward water splitting

“…By using such electrocatalysts as both cathode and anode, low‐cost water splitting electrolyzer can be realized, which avoids the usage of different equipment and processes for the different types of HER and OER electrocatalysts. Similarly, to enhance the overall water splitting performance, the electronic modulation and interface engineering of the electrocatalysts are also desirable 199‐213 …”