Coconut-Water-Mediated Carbonaceous Electrode: A Promising Eco-Friendly Material for Bifunctional Water Splitting Application

Abstract

The organic and eco-friendly materials are extended to prevail over the worldwide energy crisis where bio-inspired carbonaceous electrode materials are being prepared from biogenic items and wastes. Here, coconut water is sprayed over three-dimensional (3D) nickel foam for obtaining a carbonaceous electrode material, i.e., C@Ni-F. The as-prepared C@Ni-F electrode has been used for structural elucidation and morphology evolution studies. Field emission scanning electron microscopy analysis confirms the vertically grown nanosheets of the C@Ni-F electrode, which is further employed in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), where excellent OER and HER performances with small overpotentials of 219 and 122 mV and with stumpy Tafel slopes, i.e., 27 and 53 mV dec –1 , are respectively obtained, suggesting a bifunctional potential of the sprayed electrode material. Moreover, sustainable bifunctional performance of C@Ni-F proves considerable chemical stability and moderate mechanical robustness against long-term operation, suggesting that, in addition to being a healthy drink to mankind, coconut water can also be used for water splitting applications.

Recent advances in non‐precious Ni‐based promising catalysts for water splitting application

“…Bifunctional electrocatalysts would simplify the system by lowering the cost. The alkaline water electrolysis plays an important role in the chemical industry, which utilizes Earth's abundant metals as the electrode materials, and sometimes they reveal competitive or even better efficiency than noble metal‐based electrocatalysts, which are generally operated under acidic water electrolysis 118 . It is thus highly essential to adopt a noble metal‐free bifunctional electrocatalysts for both OER and HER operations under strong basic medium.…”

“…117 Gao et al used the electrodeposition process to synthesis the NiSe/ Ni-foam to check HER as well as OER performance where 190 and 136 mV overpotentials respectively were documented at 100 mA/cm 2 . 118 Raut et al obtained a carbonaceous electrode material in vertically grown nanosheets formed via coconut water onto 3D-Ni-foam as C@Ni-foam, which evidenced OER and HER over potentials of activity with 219 and 122 mV, respectively, and 27 and 53 mV dec À1 Tofel slopes, suggested a bifunctional efficacy of electrode materials and synthesis method, ie, spray pyrolysis. 119 120 Further, honeycomb-like heterostructure fabricated by a threestep electrodeposition/dealloying/electrodeposition strategy was composed of NiFe shell and Ni(Cu) nanotubes, as an efficient and robust bifunctional electrocatalyst for overall water splitting.…”

“…The alkaline water electrolysis plays an important role in the chemical industry, which utilizes Earth's abundant metals as the electrode materials, and sometimes they reveal competitive or even better efficiency than noble metal-based electrocatalysts, which are generally operated under acidic water electrolysis. 118 It is thus highly essential to adopt a noble metal-free bifunctional electrocatalysts for both OER and HER operations under strong basic medium. Franceschini et al prepared different Ni-based catalysts, that is, NiMo, Ni(WO 3 ), and Ni(Nb 2 O 5 ), for hydrogen evolution in NaCl-containing solutions and tested in seawater as electrolyte solution for water catalysis application.…”

“…The minimum OER and HER overpotentials of 280 and 330 mV and Tafel slopes of 77 and 127 mV −1 were obtained 117 . Gao et al used the electrodeposition process to synthesis the NiSe/Ni‐foam to check HER as well as OER performance where 190 and 136 mV overpotentials respectively were documented at 100 mA/cm 2 118 . Raut et al obtained a carbonaceous electrode material in vertically grown nanosheets formed via coconut water onto 3D‐Ni‐foam as C@Ni‐foam, which evidenced OER and HER over potentials of activity with 219 and 122 mV, respectively, and 27 and 53 mV dec −1 Tofel slopes, suggested a bifunctional efficacy of electrode materials and synthesis method, ie, spray pyrolysis 119 …”

Ulothrix-Derived Sulfur-Doped Porous Carbon for High-Performance Symmetric Supercapacitors

“…To meet these requirements, researchers mainly consider the improvement from the aspects of proper carbon sources, the activation procedure, and heteroatom doping . Many kinds of precursors were selected as carbon sources to boost the surface properties, such as biomass-derived carbon, − polymer-derived carbon, , carbide-derived carbon, and MOF-templated carbon. , Among these, biomass has been taken into account by many researchers because of its large specific area, abundant pore structure, ecofriendliness, and extensive sources . For example, various biomass products such as walnut shells, , pomelo peels, bamboo bagasse, willow catkins, cornstalks, bean curds, and garlic seeds were made into porous carbon.…”