Abstract
A total of two carbon xerogels doped with cobalt and nickel were prepared by the sol–gel method. The obtained carbon xerogels underwent further surface modification with three binary metal oxides namely: nickel cobaltite, nickel ferrite, and cobalt ferrite through the hydrothermal method. The mesopore volumes of these materials ranged between 0.24 and 0.40 cm3/g. Moreover, there was a morphology transformation for the carbon xerogels doped with nickel cobaltite, which is in the form of nano-needles after the hydrothermal process. Whereas the carbon xerogels doped with nickel ferrite and cobalt ferrite maintained the normal carbon xerogel structure after the hydrothermal process. The prepared materials were tested as electrocatalysts for oxygen reduction reaction using 0.1 M KOH. Among the prepared carbon xerogels cobalt-doped carbon xerogel had better electrocatalytic performance than the nickel-doped ones. Moreover, the carbon xerogels doped with nickel cobaltite showed excellent activity for oxygen reduction reaction due to mesoporosity development. NiCo2O4/Co-CX showed to be the best electrocatalyst of all the prepared electrocatalysts for oxygen reduction reaction application, exhibiting the highest electrocatalytic activity, lowest onset potential Eonset of −0.06 V, and the lowest equivalent series resistance (ESR) of 2.74 Ω.
Highlights
The energy problem is one of the most important challenges the world is facing
The highest surface areas were obtained for the samples doped with nickel ferrite NiFe2 O4, which means these samples have high microporosity as appears from their pore size (Lo) data
The mesoporosity development is an indication for betteraccessibility accessibility of electrolyte ions inside the carbon structure, development is an for ofelectrolyte electrolyte ions inside carbon structure, development is indication an indication forbetter better accessibility of ions inside the the carbon structure, which in turn make these materials good electrocatalysts in catalysis application [27,28,29]
Summary
The energy problem is one of the most important challenges the world is facing . Fuel cells are electrochemical devices that are able to convert chemical energy into electrical energy when fuel and oxidant are supplied [2] According to their working mechanism, fuel cell bears similarities in both batteries and engines, it has superior advantages as it does not need recharging and generates drinking water when the used fuel is hydrogen, so, it is considered as a “zero emission engine.”. Because it is environmentally friendly, fuel cells find commercial application in transportation, stationary power generation, and in low power portable devices. These difficulties can be attributed to economic factors, materials designing problem, and inadequacies in electrochemical devices operation [2,3]
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